获取Activity的返回参数应用实例:更改头像

MainActivity.java:

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if(requestCode == 0 && resultCode == 0){
            Bundle bundle = data.getExtras();
            int ImageId = bundle.getInt("imageId");
            ImageView image = findViewById(R.id.image);
            image.setImageResource(ImageId);
        }
    }

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button btn = findViewById(R.id.btn);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(MainActivity.this, Portrait.class);
                startActivityForResult(intent,0);//0是请求码
            }
        });
    }
}

activity_main.xml:

<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"
    android:gravity="center"
    >

    <ImageView
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:id="@+id/image"
        android:src="@drawable/daoqi"
        />
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="更换头像"
        android:id="@+id/btn"/>
</LinearLayout>

PortraitActivity.java:

public class LocationAcivity extends AppCompatActivity {
    private int[] image = {R.drawable.img01, R.drawable.img02, R.drawable.img03};
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_portrait);

        GridView gv = findViewById(R.id.gv);

        List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
        for (int i = 0;i <image.length;i++) {
            Map<String,Object> map = new HashMap<String, Object>();
            map.put("image",image[i]);
            list.add(map);
        }
        SimpleAdapter simpleAdapter = new SimpleAdapter(
                this,
                list,
                R.layout.item,
                new String[]{"image"},
                new int[]{R.id.touxiang}
                );
        gv.setAdapter(simpleAdapter);
        gv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
                Intent intent = new Intent();
                Bundle bundle = new Bundle();
                bundle.putInt("imageId",image[i]);
                intent.putExtras(bundle);
                setResult(0,intent);//0是返回码
                finish();
            }
        });
    }
}

activity_portrait.xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent"
    >
<GridView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:numColumns="3"
    android:id="@+id/gv">

</GridView>
</LinearLayout>

item.xml:

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    >
    <ImageView
        android:layout_width="200dp"
        android:layout_height="200dp"
        android:id="@+id/touxiang">
    </ImageView>

</RelativeLayout>

效果图: