개인적인 개발팁 모음

C# 소켓이 프로그램시,

Connected 속성으로 정확히 체크할 수 없는 경우에 다음과 같이 체크 가능하다

bool isConnCheck = !((_socket.Poll(1000, SelectMode.SelectRead) && (_socket.Available == 0)) || !_socket.Connected);

1. activity_main.xml

  - Layout : LinearLayout

  - orientaion : vertical

2. Containers > TabLayout을 붙여넣는다

  - height : wrap_content로 변경

  - 3개의 탭이 기본적으로 생성되어 있는데 각각의 텍스트를 '즐겨찾기', '노선', '정류장'으로 바꾼다

* 탭 레이아웃이 위로 올려붙는다

3. 탭 레이아웃 하단에는 FrameLayout을 붙인다

  - id : container

> 지금까지의 화면은 다음과 같이 표현된다

  4. Fragment생성

    1) Bookmark 

2) 경로

3) StationFragment 

* 탭 관련 초기 코드

	//선언
    enum eFragment{ Bookmark, Route, Station, FragMax};
    Fragment [] fragments = new Fragment[3];
    public int tabIndex = 0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
	//.....

        tabIndex = eFragment.Bookmark.ordinal();
        fragments[eFragment.Bookmark.ordinal()] = new BookmarkFragment();
        fragments[eFragment.Route.ordinal()]    = new RouteFragment();
        fragments[eFragment.Station.ordinal()]  = new StationFragment();

        getSupportFragmentManager().beginTransaction().replace(R.id.container, fragments[tabIndex]).commit();

        TabLayout tabs = findViewById(R.id.tabs);
        tabs.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                int idx = tabs.getSelectedTabPosition();
                getSupportFragmentManager().beginTransaction().replace(R.id.container, fragments[idx]).commit();
            }

            @Override
            public void onTabUnselected(TabLayout.Tab tab) {

            }

            @Override
            public void onTabReselected(TabLayout.Tab tab) {

            }
        });
	}

여기까지 하면 기본적으로 탭이 보이고 탭으로 Fragment가 바뀌는 것은 볼수 있다

1. 클래스 생성(Station 정보)

public class Station {
    public String bstopid;
    public String bstopnm;
    public String arsno;
    public String gpsx;
    public String gpsy;
    public String stoptype;

    public void clear(){
        bstopid = "";
        bstopnm = "";
        arsno   = "";
        gpsx    = "";
        gpsy    = "";
        stoptype = "";
    }

    boolean checkRecvAllData(){
        return bstopid.length()  > 0
            && bstopnm.length()  > 0
            && arsno.length()    > 0
            && gpsx.length()     > 0
            && gpsy.length()     > 0
            && stoptype.length() > 0;
    }
}

참고로 수신 받는 데이터의 형태는 아래와 같다

2. 수신 받는 루틴은 다음과 같고 ArrayList에 담을 수 있다

	String curr_tag = "";
	ArrayList<Station> arrStation = new ArrayList<>();
	Station station = new Station();

	try {
		XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
		factory.setNamespaceAware(true);
		XmlPullParser xpp = factory.newPullParser();

		xpp.setInput( new StringReader(response) );
		int eventType = xpp.getEventType();
		while (eventType != XmlPullParser.END_DOCUMENT) {
			if(eventType == XmlPullParser.START_DOCUMENT) {
				//System.out.println("Start document");
			} else if(eventType == XmlPullParser.START_TAG) {
				//시작하는 tag 기억
				curr_tag = xpp.getName();
				if(xpp.getName().equals("item")){
					station.clear();
				}
			} else if(eventType == XmlPullParser.END_TAG) {
				//item 태그 종료시 추가 
				if(xpp.getName().equals("item")){
					if(station.checkRecvAllData())
						arrStation.add(station);
				}
				curr_tag = "";
			} else if(eventType == XmlPullParser.TEXT) {
				//태그 종류별로 기록
				switch(curr_tag)
				{
					case "bstopid": station.bstopid  = xpp.getText(); break;
					case "bstopnm": station.bstopnm  = xpp.getText(); break;
					case "arsno":   station.arsno    = xpp.getText(); break;
					case "gpsx":    station.gpsx     = xpp.getText(); break;
					case "gpsy":    station.gpsy     = xpp.getText(); break;
					case "stoptype":station.stoptype = xpp.getText(); break;
				}
			}
			eventType = xpp.next();
		}

	} catch (Exception e) {
		e.printStackTrace();
	}

4. 그러면 RecyclerView에 표현하기 위해서 Adapter를 만들어야 한다

1) Adapter를 만들기 위해서 그전에 ViewHolder를 inner class로 만든다

public class StationAdapter{
//버스 정류장 id와 이름을 표현할 text view를 찾는다
//화면에 표시하기 위한 메소드 정의( setItem )
static class ViewHolder extends RecyclerView.ViewHolder {
        TextView bus_id;
        TextView bus_nm;
        public ViewHolder(@NonNull View itemView) {
            super(itemView);

            bus_id = itemView.findViewById(R.id.bus_id);
            bus_nm = itemView.findViewById(R.id.bus_name);
        }

        public void setItem(Station station){
            bus_id.setText(station.bstopid);
            bus_nm.setText(station.bstopnm);
        }
    }


}

2) 그리고 나서 Adapter를 완성한다

  OnCreateViewHolder는 메모리에 생성할 때 쓰여지는 메소드이고, onBindViewHolder는 이미 생성된 ViewHolder를 재사용할 때 사용되는 메소드이다

public class StationAdapter extends RecyclerView.Adapter<StationAdapter.ViewHolder>{

    ArrayList<Station> items = new ArrayList<Station>();

    public void setItems(ArrayList<Station> items){this.items = items;}

    public void clearItems(){ items.clear(); }
    public void addItem(Station station){ items.add(station); }

    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        LayoutInflater inflater = LayoutInflater.from(parent.getContext());
        View itemView = inflater.inflate(R.layout.station_item, parent, false);
        return new ViewHolder(itemView);
    }

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        Station item =items.get(position);
        holder.setItem(item);
    }

    @Override
    public int getItemCount() {
        return items.size();
    }

    static class ViewHolder extends RecyclerView.ViewHolder {
        TextView bus_id;
        TextView bus_nm;
        public ViewHolder(@NonNull View itemView) {
            super(itemView);

            bus_id = itemView.findViewById(R.id.bus_id);
            bus_nm = itemView.findViewById(R.id.bus_name);
        }

        public void setItem(Station station){
            bus_id.setText(station.bstopid);
            bus_nm.setText(station.bstopnm);
        }
    }
}

3. 그럼 MainActivity에서 다음과 같은 작업을 진행한다

아래와 같은 절차를 거친다

//1. adapter 생성
adapter = new StationAdapter();
//2. RecyclerView 변수 할당
rvStation = findViewById(R.id.rvStation);
//3. RecyclerView에 layoutManager 할당
LinearLayoutManager layoutManager = new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false);
rvStation.setLayoutManager(layoutManager);
//4. RecyclerView에 adapter 할당
rvStation.setAdapter(adapter);

//5. item 태그가 시작되면 Station 새로운 메모리 할당
//같은 객체를 계속 쓰면 리스트에 모두 같은 객체를 참조하므로 같은 출력물이 나온다

//6. xml 수신 받기 시작할 때 adapter의 리스트 clear
adapter.clearItems();

//7. 객체 하나가 완성되면 adapter에 add
adapter.addItem(station);

//8. 수신이 완료되면 adapter에 notify
adapter.notifyDataSetChanged();

4. 완성 코드는 다음과 같다 (개발자 코드는 숨겼음)

package com.hdongle.busanbusstationinfotest;

import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

import com.android.volley.AuthFailureError;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.android.volley.toolbox.Volley;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.StringReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;
import org.xmlpull.v1.XmlPullParserFactory;


public class MainActivity extends AppCompatActivity {

    RecyclerView rvStation;
    static RequestQueue requestQueue;
    String TAG = "STATION LIST";
    StationAdapter adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        LinearLayoutManager layoutManager = new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false);

        adapter = new StationAdapter();
        rvStation = findViewById(R.id.rvStation);
        rvStation.setLayoutManager(layoutManager);
        rvStation.setAdapter(adapter);

        requestQueue = Volley.newRequestQueue(getApplicationContext());

        Button btn = findViewById(R.id.btnRequest);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                StringRequest request = new StringRequest(
                        Request.Method.GET,
                        "http://apis.data.go.kr/6260000/BusanBIMS/busStopList?serviceKey=__________&pageNo=1&numOfRows=100",
                        new Response.Listener<String>() {
                            @Override
                            public void onResponse(String response) {
                                //Log.d(TAG, "onResponse : " + response);

                                String curr_tag = "";
                                //ArrayList<Station> arrStation = new ArrayList<>();
                                Station station = new Station();
                                adapter.clearItems();

                                try {
                                    XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
                                    factory.setNamespaceAware(true);
                                    XmlPullParser xpp = factory.newPullParser();

                                    xpp.setInput( new StringReader(response) );
                                    int eventType = xpp.getEventType();
                                    while (eventType != XmlPullParser.END_DOCUMENT) {
                                        if(eventType == XmlPullParser.START_DOCUMENT) {
                                            //System.out.println("Start document");
                                        } else if(eventType == XmlPullParser.START_TAG) {
                                            //시작하는 tag 기억
                                            curr_tag = xpp.getName();
                                            if(xpp.getName().equals("item")){
                                                station = new Station();
                                            }
                                        } else if(eventType == XmlPullParser.END_TAG) {
                                            //item 태그 종료시 추가 
                                            if(xpp.getName().equals("item")){
                                                if(station.checkRecvAllData()){
                                                    adapter.addItem(station);
                                                }
                                                    //arrStation.add(station);
                                            }
                                            curr_tag = "";
                                        } else if(eventType == XmlPullParser.TEXT) {
                                            //태그 종류별로 기록
                                            switch(curr_tag)
                                            {
                                                case "bstopid": station.bstopid  = xpp.getText(); break;
                                                case "bstopnm": station.bstopnm  = xpp.getText(); break;
                                                case "arsno":   station.arsno    = xpp.getText(); break;
                                                case "gpsx":    station.gpsx     = xpp.getText(); break;
                                                case "gpsy":    station.gpsy     = xpp.getText(); break;
                                                case "stoptype":station.stoptype = xpp.getText(); break;
                                            }
                                        }
                                        eventType = xpp.next();
                                    }

                                } catch (Exception e) {
                                    e.printStackTrace();
                                }

                                //System.out.println("Count : " + arrStation.size());
                                adapter.notifyDataSetChanged();
                                Toast.makeText(getApplicationContext(), "수신완료", Toast.LENGTH_LONG).show();
                            }

                        },
                        new Response.ErrorListener() {
                            @Override
                            public void onErrorResponse(VolleyError error) {
                                Log.d(TAG, "onErrorResponse : " + error.toString());
                            }
                        }
                ){
                    //요청 파라미터를 처리하는 메소드
                    @Nullable
                    @Override
                    protected Map<String, String> getParams() throws AuthFailureError {
                        //요청 객체가 하나 만들어짐
                        Map<String, String> params = new HashMap<String, String>();
                        //요청 큐에 넣어주면 된다

                        return super.getParams();
                    }
                };
                request.setShouldCache(false);
                requestQueue.add(request);
            }
        });

        //XmlParserCreator  parserCreator;
/*
        XmlParserCreator parserCreator = new XmlParserCreator() {
            @Override
            public XmlPullParser createParser() {
                try {
                    return XmlPullParserFactory.newInstance().newPullParser();
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }
            }
        };

        GsonXml gsonXml = new GsonXmlBuilder()
                .setXmlParserCreator(parserCreator)
                .create();
 */
    }


}

결과는 다음과 같다. 

허접하긴 한데, 뭔가 나왔다는데 의의를 둔다..ㅎㅎㅎ

* 데이터 송수신을 위해 Volley라는 라이브러리를 사용한다.

 - 스레드를 이용해서 그냥 만들어도 상관은 없다

1. 라이브러리 추가

1) File > Project Structure 메뉴 선택

2. Project Structure 창이 나타나면 Dependencies > app > '+' > Library Dependency 선택

3. Add Library Dependency 창이 나타나면 

  com.android.volly

  입력하고 Search 버튼을 누르면 목록이 나오는데, 최신 버전을 선택 후 OK 버튼을 누른다

4. 추가된 volly가 목록에 있는지 확인 후 OK 버튼을 선택한다

* 참고로 build.gradle 에 volley가 추가 되어 있음을 확인 할 수 있다

5. Main Activity에서 Volley를 이용해서 요청하고 수신 받아 로그로 출력해본다

package com.hdongle.busanbusstationinfotest;

import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;

import com.android.volley.AuthFailureError;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.android.volley.toolbox.Volley;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;


public class MainActivity extends AppCompatActivity {

    static RequestQueue requestQueue;
    String TAG = "STATION LIST";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        requestQueue = Volley.newRequestQueue(getApplicationContext());

        Button btn = findViewById(R.id.btnRequest);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                StringRequest request = new StringRequest(
                        Request.Method.GET,
                        "http://apis.data.go.kr/6260000/BusanBIMS/busStopList?serviceKey=___________________________&pageNo=1&numOfRows=100",
                        new Response.Listener<String>() {
                            @Override
                            public void onResponse(String response) {
                                Log.d(TAG, "onResponse : " + response);
                            }

                        },
                        new Response.ErrorListener() {
                            @Override
                            public void onErrorResponse(VolleyError error) {
                                Log.d(TAG, "onErrorResponse : " + error.toString());
                            }
                        }
                ){
                    //요청 파라미터를 처리하는 메소드
                    @Nullable
                    @Override
                    protected Map<String, String> getParams() throws AuthFailureError {
                        //요청 객체가 하나 만들어짐
                        Map<String, String> params = new HashMap<String, String>();
                        //요청 큐에 넣어주면 된다

                        return super.getParams();
                    }
                };
                request.setShouldCache(false);
                requestQueue.add(request);
            }
        });
    }


}

6. Manifest.xml에 INTERNET 권한을 추가한다 (2군데)

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.hdongle.busanbusstationinfotest">

    <!-- 추가한 부분 1-->
    <uses-permission android:name="android.permission.INTERNET"/>

    <!-- 추가한 부분 2 : android:usesCleartextTraffic -->
    <application
        android:usesCleartextTraffic="true"    
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.BusanBusStationInfoTest">
        <activity
            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

7. 다음과 같이 데이터 수신을 확인할 수 있다

1. Manifest.xml

1) 전화번호부

    <uses-permission android:name="android.permission.READ_CONTACTS"/>
    <uses-permission android:name="android.permission.WRITE_CONTACTS"/>

2. build.gradle

dependencies {

    ----기존에 있던 목록--------------------------------------------
    implementation 'com.github.pedroSG94:AutoPermissions:1.0.3'
}

3. setting.gradle

dependencyResolutionManagement {
    repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
    repositories {
        ------기존에 있던 목록-----------------------------------
        maven {url "https://www.jitpack.io"}
    }
}

4. 인터페이스 상속

//변경 전
public class MainActivity extends AppCompatActivity

//변경 후
public class MainActivity extends AppCompatActivity implements AutoPermissionsListener

5. onCreate

@Override
protected void onCreate(Bundle savedInstanceState) {
	super.onCreate(savedInstanceState);
	//---작성 코드들 ------------------------------
	AutoPermissions.Companion.loadAllPermissions(this, 101);
}

6. Generate

@Override
    public void onDenied(int i, String[] strings) {

    }

    @Override
    public void onGranted(int i, String[] strings) {

    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        AutoPermissions.Companion.parsePermissions(this, requestCode, permissions,  this);
    }

* 개발 도구 : 안드로이드스튜디오 Acrtic Fox(2020.3.1 Patch3)

1. 공공데이터 사이트 가입

 - URL : https://www.data.go.kr/index.do

2. 데이터 신청

 - URL : https://www.data.go.kr/data/15092750/openapi.do

  - "활용신청" 버튼을 눌러서 데이터 신청

  - 신청이 승이되면 serviceKey를 부여받음

3. API 테스트

  - 브라우저에서 다음의 url을 입력 테스트

  - http://apis.data.go.kr/6260000/BusanBIMS/busStopList?serviceKey=서비스키&pageNo=1&numOfRows=10 

4. 안드로이드 스튜디오 프로젝트 생성(프로젝트명 : BusanBusStationInfoTest) 

5. activity_main.xml 

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity" >

    <Button
        android:id="@+id/btnRequest"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="요청하기" />

    <androidx.recyclerview.widget.RecyclerView
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
</LinearLayout>

6. 레이아웃 생성(station_item.xml)

7. 다음의 image를 res/dawable로 복사

8. 레이아웃을 다음과 같이 구성한다.

  (imageView / id / nm)

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">

    <androidx.cardview.widget.CardView
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal">

            <ImageView
                android:id="@+id/imageView"
                android:layout_width="110dp"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                app:srcCompat="@drawable/station" />

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:layout_weight="1"
                android:orientation="vertical">

                <TextView
                    android:id="@+id/id"
                    android:layout_width="match_parent"
                    android:layout_height="0dp"
                    android:layout_weight="1"
                    android:gravity="center_horizontal|center_vertical"
                    android:text="TextView" />

                <TextView
                    android:id="@+id/name"
                    android:layout_width="match_parent"
                    android:layout_height="0dp"
                    android:layout_weight="1"
                    android:gravity="center_horizontal|center_vertical"
                    android:text="TextView" />
            </LinearLayout>

        </LinearLayout>
    </androidx.cardview.widget.CardView>
</LinearLayout>

1. MainActivity

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:orientation="vertical">

        <com.google.android.material.tabs.TabLayout
            android:id="@+id/tabRoot"
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <com.google.android.material.tabs.TabItem
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="탭1" />

            <com.google.android.material.tabs.TabItem
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="탭2" />

            <com.google.android.material.tabs.TabItem
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="탭3" />

            <com.google.android.material.tabs.TabItem
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="탭4" />
        </com.google.android.material.tabs.TabLayout>
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <FrameLayout
            android:id="@+id/tab_container"
            android:layout_width="match_parent"
            android:layout_height="match_parent">

        </FrameLayout>
    </LinearLayout>
</LinearLayout>

package org.hdongle.layouttest;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import com.google.android.material.tabs.TabLayout;

public class MainActivity extends AppCompatActivity {
    TabLayout tabRoot;
    Fragment1 fragment1;
    Fragment2 fragment2;
    Fragment3 fragment3;
    Fragment4 fragment4;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        fragment1 = new Fragment1();
        fragment2 = new Fragment2();
        fragment3 = new Fragment3();
        fragment4 = new Fragment4();

        tabRoot = findViewById(R.id.tabRoot);
        tabRoot.removeAllTabs();
        tabRoot.addTab(tabRoot.newTab().setText("1번탭"));
        tabRoot.addTab(tabRoot.newTab().setText("2번탭"));
        tabRoot.addTab(tabRoot.newTab().setText("3번탭"));
        tabRoot.addTab(tabRoot.newTab().setText("4번탭"));

        getSupportFragmentManager().beginTransaction().replace(R.id.tab_container, fragment1).commit();

        tabRoot.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                switch(tab.getPosition())
                {
                    case 0:
                        getSupportFragmentManager().beginTransaction().replace(R.id.tab_container, fragment1).commit();
                        break;
                    case 1:
                        getSupportFragmentManager().beginTransaction().replace(R.id.tab_container, fragment2).commit();
                        break;
                    case 2:
                        getSupportFragmentManager().beginTransaction().replace(R.id.tab_container, fragment3).commit();
                        break;
                    case 3:
                        getSupportFragmentManager().beginTransaction().replace(R.id.tab_container, fragment4).commit();
                        break;
                }
            }

            @Override
            public void onTabUnselected(TabLayout.Tab tab) {

            }

            @Override
            public void onTabReselected(TabLayout.Tab tab) {

            }
        });

    }
}

2. Tab1 & Fragment1

 - getChildFragmentManager()를 활용한 중첩 Fragment

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="100dp"
        android:orientation="vertical">

        <EditText
            android:id="@+id/editTextTextPersonName2"
            android:layout_width="match_parent"
            android:layout_height="50dp"
            android:ems="10"
            android:inputType="textPersonName"
            android:text="Name" />

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="horizontal">

            <Button
                android:id="@+id/btn1_1"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginLeft="4dp"
                android:layout_marginRight="2dp"
                android:layout_weight="1"
                android:text="탭1-1" />

            <Button
                android:id="@+id/btn1_2"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginLeft="2dp"
                android:layout_marginRight="2dp"
                android:layout_weight="1"
                android:text="탭1-2" />

            <Button
                android:id="@+id/btn1_3"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginLeft="2dp"
                android:layout_marginRight="4dp"
                android:layout_weight="1"
                android:text="탭1-3" />

        </LinearLayout>
    </LinearLayout>

    <FrameLayout
        android:id="@+id/tab1_container"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</LinearLayout>

public class Fragment1 extends Fragment {
    Fragment1_1 fragment1_1;
    Fragment1_2 fragment1_2;
    Fragment1_3 fragment1_3;

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        //return super.onCreateView(inflater, container, savedInstanceState);
        ViewGroup rootView = (ViewGroup) inflater.inflate(R.layout.fragment1, container, false);

        fragment1_1 = new Fragment1_1();
        fragment1_2 = new Fragment1_2();
        fragment1_3 = new Fragment1_3();

        getChildFragmentManager().beginTransaction().replace(R.id.tab1_container, fragment1_1).commit();

        Button btn = rootView.findViewById(R.id.btn1_1);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                getChildFragmentManager().beginTransaction().replace(R.id.tab1_container, fragment1_1).commit();
            }
        });

        btn = rootView.findViewById(R.id.btn1_2);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                getChildFragmentManager().beginTransaction().replace(R.id.tab1_container, fragment1_2).commit();
            }
        });

        btn = rootView.findViewById(R.id.btn1_3);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                getChildFragmentManager().beginTransaction().replace(R.id.tab1_container, fragment1_3).commit();
            }
        });

        return rootView;
    }
}

3. 1-1 화면들(1-2, 1-3 화면은 생략)

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <TextView
            android:id="@+id/textView"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="4dp"
            android:text="Tab1_1 - Top"
            android:textSize="30sp"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.498"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <TextView
            android:id="@+id/textView2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:gravity="bottom"
            android:text="Tab1_1 - Bottom"
            android:textSize="30sp"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent" />
    </androidx.constraintlayout.widget.ConstraintLayout>

</LinearLayout>

package org.hdongle.layouttest;

import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;

public class Fragment1_1 extends Fragment {
    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        //return super.onCreateView(inflater, container, savedInstanceState);
        ViewGroup rootView = (ViewGroup) inflater.inflate(R.layout.fragment1_1, container, false);
        return rootView;
    }
}

4. Fragment2(Fragment3, 4는 생략)

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <TextView
            android:id="@+id/textView"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="4dp"
            android:text="Tab2 - Top"
            android:textSize="30sp"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.498"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <TextView
            android:id="@+id/textView2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:gravity="bottom"
            android:text="Tab2 - Bottom"
            android:textSize="30sp"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent" />
    </androidx.constraintlayout.widget.ConstraintLayout>

</LinearLayout>

package org.hdongle.layouttest;

import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;

public class Fragment2 extends Fragment {
    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        //return super.onCreateView(inflater, container, savedInstanceState);
        ViewGroup rootView = (ViewGroup) inflater.inflate(R.layout.fragment2, container, false);
        return rootView;
    }
}

1. Empty Activity 프로젝트 생성

2. 프로젝트에서 마우스 우클릭 > New > Layout Resource File > fragment_top.xml 입력

3. 2번에서 생성한 Layout 변경

  1) Layout : Linear Layout(orientation : vertical)

  2) 상단에 Plain Text

  3) 하단에 Linear Layout (orientation : horizontal) - 버튼 5개

4. java class 추가 : TopFragment.java

5. fragment_bottom_all.xml Layout 생성

  * TextView 추가

    - Text : "전체화면"

    - TextSize : 30sp

6. 같은 방법으로 layout들을 추가한다

  1) fragment_bottom_1.xml

  2) fragment_bottom_2.xml

  3) fragment_bottom_3.xml

  4) fragment_bottom_4.xml

7. 생성한 layout들과 연결될 java class를 생성함

1) TopFragment.java

public class TopFragment extends Fragment {

    @Override
    public void onAttach(@NonNull Context context) {
        super.onAttach(context);
    }

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        //return super.onCreateView(inflater, container, savedInstanceState);

        //Layout xml과 연결
        ViewGroup rootView = (ViewGroup)inflater.inflate(R.layout.fragment_top, container, false);

        Button btnAll = rootView.findViewById(R.id.btnAll);
        btnAll.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                MainActivity mainActivity = (MainActivity)getActivity();
                if(mainActivity != null)
                    mainActivity.FragmentChange(0);
            }
        });
        Button btn1 = rootView.findViewById(R.id.btn1);
        btn1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                MainActivity mainActivity = (MainActivity)getActivity();
                if(mainActivity != null)
                    mainActivity.FragmentChange(1);
            }
        });
        Button btn2 = rootView.findViewById(R.id.btn2);
        btn2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                MainActivity mainActivity = (MainActivity)getActivity();
                if(mainActivity != null)
                    mainActivity.FragmentChange(2);
            }
        });
        Button btn3 = rootView.findViewById(R.id.btn3);
        btn3.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                MainActivity mainActivity = (MainActivity)getActivity();
                if(mainActivity != null)
                    mainActivity.FragmentChange(3);
            }
        });
        Button btn4 = rootView.findViewById(R.id.btn4);
        btn4.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                MainActivity mainActivity = (MainActivity)getActivity();
                if(mainActivity != null)
                    mainActivity.FragmentChange(4);
            }
        });
        return rootView;
    }
}

2) BottomAllFragment.java

public class BottomAllFragment extends Fragment {
    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        //return super.onCreateView(inflater, container, savedInstanceState);
        ViewGroup rootView = (ViewGroup)inflater.inflate(R.layout.fragment_bottom_all, container, false);

        return rootView;
    }
}

3) Bottom1Fragment.java

public class Bottom1Fragment extends Fragment {
    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        //return super.onCreateView(inflater, container, savedInstanceState);
        ViewGroup rootView = (ViewGroup)inflater.inflate(R.layout.fragment_bottom_1, container, false);

        return rootView;
    }
}

4) Bottom2Fragment.java

public class Bottom2Fragment extends Fragment {
    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        //return super.onCreateView(inflater, container, savedInstanceState);
        ViewGroup rootView = (ViewGroup)inflater.inflate(R.layout.fragment_bottom_2, container, false);

        return rootView;
    }
}

5) Bottom3Fragment.java

public class Bottom3Fragment extends Fragment {
    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        //return super.onCreateView(inflater, container, savedInstanceState);
        ViewGroup rootView = (ViewGroup)inflater.inflate(R.layout.fragment_bottom_3, container, false);

        return rootView;
    }
}

6) Bottom4Fragment.java

public class Bottom4Fragment extends Fragment {
    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        //return super.onCreateView(inflater, container, savedInstanceState);
        ViewGroup rootView = (ViewGroup)inflater.inflate(R.layout.fragment_bottom_4, container, false);

        return rootView;
    }
}

8. MainActivity를 다음과 같이 코딩한다

1) MainActivity.java

public class MainActivity extends AppCompatActivity {

    private FragmentManager fragmentManager;
    private Fragment[] fragments;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        fragmentManager = (FragmentManager)getSupportFragmentManager();
        fragments = new Fragment[5];
        fragments[0] = new BottomAllFragment();
        fragments[1] = new Bottom1Fragment();
        fragments[2] = new Bottom2Fragment();
        fragments[3] = new Bottom3Fragment();
        fragments[4] = new Bottom4Fragment();

        FragmentChange(0);

    }

    public void FragmentChange(int idx)
    {
        if(idx >=0 && idx < 5)
        {
            fragmentManager.beginTransaction().replace(R.id.bottom_container, fragments[idx]).commit();
        }
    }
}

2) activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">


    <FrameLayout
        android:id="@+id/top_container"
        android:layout_width="match_parent"
        android:layout_height="100dp">
        <fragment
            android:id="@+id/topFragment"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:name="org.hdongle.tab2test.TopFragment">
        </fragment>
    </FrameLayout>

    <FrameLayout
        android:id="@+id/bottom_container"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
    </FrameLayout>
</LinearLayout>

1. Fragment 생성(MainFragment, MenuFragment)

2. 다음의 창이 나타나면 이름 입력(TestFrament => MainFragment)

3. MainFragment는 MainActivity의 xml에 바로 등록한다. MainActivity는 FrameLayout으로 변경

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" >
    <fragment
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:name="org.hdongle.fragment.MainFragment"
        android:id="@+id/mainFragment">

    </fragment>
</FrameLayout>

4. 각각의 fragment들을 다음과 같이 바꾼다

* fragment_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#FFEB3B"
    android:orientation="vertical"
    tools:context=".MainFragment">

    <TextView
        android:id="@+id/textView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center|center_vertical"
        android:text="메인 프레그먼트"
        android:textSize="50sp" />

    <Button
        android:id="@+id/button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#FFC107"
        android:text="화면전환" />
</LinearLayout>

* fragment_menu.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#0000FF"
    android:orientation="vertical"
    tools:context=".MainFragment">

    <TextView
        android:id="@+id/textView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center|center_vertical"
        android:text="메뉴 프레그먼트"
        android:textSize="50sp" />

    <Button
        android:id="@+id/button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#FFC107"
        android:text="돌아가기" />
</LinearLayout>

5. Fragment들의 java에 다음과 같이 코딩한다

*MainFragment.java

package org.hdongle.fragment;

import android.os.Bundle;

import androidx.fragment.app.Fragment;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;

public class MainFragment extends Fragment {

    //xml layout을 메모리에 올리는 역할을 한다.
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        //return inflater.inflate(R.layout.fragment_main, container, false);
        ViewGroup vg = (ViewGroup)inflater.inflate(R.layout.fragment_main, container, false);
        Button button = vg.findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                MainActivity mainActivity = (MainActivity)getActivity();
                mainActivity.OnFragmentChanged(1);
            }
        });

        return vg;
    }
}

* MenuFragment.java

package org.hdongle.fragment;

import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;

import androidx.fragment.app.Fragment;

public class MenuFragment extends Fragment {

    //xml layout을 메모리에 올리는 역할을 한다.
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        ViewGroup rootView = (ViewGroup)inflater.inflate(R.layout.fragment_menu, container, false);

        Button button = rootView.findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                MainActivity activity = (MainActivity)getActivity();
                activity.OnFragmentChanged(0);
            }
        });

        return rootView;
        //return inflater.inflate(R.layout.fragment_menu, container, false);
    }
}

6. MainActivity에 다음과 같이 코드를 넣어준다

* 핵심 코드 : container(FrameLayout)에 Fragment를 교체해준다

public class MainActivity extends AppCompatActivity {

    MainFragment mainFragment;
    MenuFragment menuFragment;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mainFragment = (MainFragment)getSupportFragmentManager().findFragmentById(R.id.mainFragment);
        menuFragment = new MenuFragment();
    }

    public void OnFragmentChanged(int idx)
    {
        if(idx == 0)
        {
            getSupportFragmentManager().beginTransaction().replace(R.id.container, mainFragment).commit();
        }
        else if(idx == 1){
            getSupportFragmentManager().beginTransaction().replace(R.id.container, menuFragment).commit();
        }
    }
}

1. Main Activity의 Layout을 LinearLayout으로 변경, orientation은 Vertical로 변경

2. 다음과 같은 구조로 컨트롤 추가

 * LinearLayout(vertical)

     > LinearLayout(horizontal)

         > Button(id:btnView1, layout_width:0dp, layout_marginLeft:10dp, layout_marginRight:5dp, layout_weight:1, text:1번화면)

         > Button(id:btnView2, layout_width:0dp, layout_marginLeft: 5dp, layout_marginRight:5dp, layout_weight:1, text:2번화면)

         > Button(id:btnView1, layout_width:0dp, layout_marginLeft: 5dp, layout_marginRight:10dp, layout_weight:1, text:3번화면)

     > LinearLayout(id : container)

3. 좌측 프로젝트 창에서 app/res/layout 메뉴에서 마우스 우클릭한 뒤 나타나는 메뉴에서 New > Activity > Empty Activity 선택 후 activity를 3개 생성한다. (sub1.xml, sub2.xml, sub3.xml)

4. 각 Activity의 Layout을 LinearLayout(vertical)로 변경 후 각 화면에 TextView 하나씩 추가 한 뒤 화면 번호 입력

5. 다음과 같이 하면 View가 계속 바뀔줄 알았는데, 한번만 바뀌고 마네..-_-

public class MainActivity extends AppCompatActivity {

    LinearLayout container;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Button btn = findViewById(R.id.btnView1);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                ChangeView(0);
            }
        });

        btn = findViewById(R.id.btnView2);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                ChangeView(1);
            }
        });

        btn = findViewById(R.id.btnView3);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                ChangeView(2);
            }
        });

        container = findViewById(R.id.container);
    }

    public void ChangeView(int index)
    {
        LayoutInflater inflater = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        container.removeAllViews();
        
        switch(index)
        {
            case 0:
                inflater.inflate(R.layout.sub1, container, true);
                //inflater.inflate(null, container, true);
                break;
            case 1:
                inflater.inflate(R.layout.sub2, container, true);
                //inflater.inflate(null, container, true);
                break;
            case 2:
                inflater.inflate(R.layout.sub3, container, true);
                //inflater.inflate(null, container, true);
                break;
        }


    }
}