한 화면에 2개의 프래그먼트

fragment_list.xml

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

    <Button
        android:id="@+id/button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="img 1" />

    <Button
        android:id="@+id/button2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="img 2" />

    <Button
        android:id="@+id/button3"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="img 3" />
</LinearLayout>

 

 

fragment_viewer.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"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:srcCompat="@drawable/dream01" />
</LinearLayout>

 

 

 

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">

    <androidx.fragment.app.FragmentContainerView
        android:id="@+id/listFragment"
        android:name="com.example.a29_samplefragment2.ListFragment"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />

    <androidx.fragment.app.FragmentContainerView
        android:id="@+id/viewerFragment"
        android:name="com.example.a29_samplefragment2.ViewerFragment"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />
</LinearLayout>

 

 

 

ListFragment

package com.example.a29_samplefragment2;

import android.content.Context;
import android.media.Image;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;

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

public class ListFragment extends Fragment {

//    중첩 인터페이스는 주로 UI 프로그래밍에서 이벤트를 처리할 목적으로 많이 활용된다
//    프래그먼트에서 인터페이스로 정의한 후, 액티비티가 이 인터페이스를 구현하도록 하는 것이 좋다
    public static interface ImageSelectionCallback {

        public void onImageSelected(int position);

    }

    public ImageSelectionCallback callback;

//   onAttach - 프래그먼트가 액티비티 위에 올라오는 시점에 호출
    @Override
    public void onAttach(Context context) {
        super.onAttach(context);

        if (context instanceof ImageSelectionCallback) {
            callback = (ImageSelectionCallback) context;
        }
    }

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        ViewGroup rootView = (ViewGroup) inflater.inflate(R.layout.fragment_list, container, false);
        
//        각각의 버튼을 클릭했을 때 callback 객체의 onImageSelected 메소드 호출

        Button button = rootView.findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (callback != null) {
                    callback.onImageSelected(0);
                }
            }
        });

        Button button2 = rootView.findViewById(R.id.button2);
        button2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (callback != null) {
                    callback.onImageSelected(1);
                }
            }
        });

        Button button3 = rootView.findViewById(R.id.button3);
        button3.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (callback != null) {
                    callback.onImageSelected(2);
                }
            }
        });

        return rootView;
    }
}

 

 

ViewerFragment

package com.example.a29_samplefragment2;

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

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

public class ViewerFragment extends Fragment {
    ImageView imageView;

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

        imageView = rootView.findViewById(R.id.imageView);
        return rootView;
    }

//    메인액티비티에서 여기의 이미지뷰의 이미지 설정
    public void setImage(int resId) {
        imageView.setImageResource(resId);
    }
}

 

 

 

MainActivity

package com.example.a29_samplefragment2;

import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.FragmentManager;

import android.os.Bundle;

// ListFragment 클래스의 ImageSelectionCallback 인터페이스 구현
public class MainActivity extends AppCompatActivity implements ListFragment.ImageSelectionCallback {

    ListFragment listFragment;
    ViewerFragment viewerFragment;

    int[] images = {R.drawable.dream01, R.drawable.dream02, R.drawable.dream03};

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

        FragmentManager manager = getSupportFragmentManager();
        listFragment = (ListFragment) manager.findFragmentById(R.id.listFragment);
        viewerFragment = (ViewerFragment) manager.findFragmentById(R.id.viewerFragment);
    }


    @Override
    public void onImageSelected(int position) {
        
//        VierFragment의 이미지뷰 설정
        viewerFragment.setImage(images[position]);
    }
}