二、实例： Ⅰ、功能：
实现两个activity （activity1、activity2）返回主activity（Mainactivity）时传值给Mainactivity
Ⅱ、布局：
activity1/activity2
mainactivity
Ⅲ、java代码：
activity1
import androidx.appcompat.app.AppCompatActivity;
public class ACTIVITY1 extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity1_);
final Button btn = (Button) findViewById(R.id.button);
btn.setonClickListener(new View.onClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent();
intent.putExtra("msg", "我来自ACTIVITY1！");
setResult(RESULT_OK,intent);
finish();
}
});
}
}
activity2
public class ACTIVITY2 extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_2);
final Button btn2 = (Button) findViewById(R.id.button2);
btn2.setonClickListener(new View.onClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent();
intent.putExtra("msg", "我来自ACTIVITY2！");
setResult(RESULT_OK, intent);
finish();
}
});
}
}
mainactivity：
public class MainActivity extends AppCompatActivity {
private static final int ACTIVITY1 = 1;
private static final int ACTIVITY2 = 2;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final Button btnmain1 = (Button) findViewById(R.id.button_main1);
final TextView textView = (TextView) findViewById(R.id.textViewmain);
btnmain1.setonClickListener(new View.onClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(MainActivity.this, ACTIVITY1.class);
startActivityForResult(intent, ACTIVITY1);
}
});
final Button btnmain2 = (Button) findViewById(R.id.button_main2);
btnmain2.setonClickListener(new View.onClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(MainActivity.this, ACTIVITY2.class);
startActivityForResult(intent, ACTIVITY2);
}
});
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
String msg = data.getStringExtra("msg");
final TextView textViewmain = (TextView) findViewById(R.id.textViewmain);
switch (requestCode) {
case ACTIVITY1:
if (resultCode == RESULT_OK)
textViewmain.setText("数据来自ACTIVITY1：" + msg);
break;
case ACTIVITY2:
if (resultCode == RESULT_OK)
textViewmain.setText("数据来自ACTIVITY2：" + msg);
break;
default:
}
}
}
Ⅳ、⭐⭐⭐实现过程⭐⭐⭐
主界面单机按钮→发送请求码并跳转到界面2→界面2单机返回按钮→界面2提供需要返回的数据和结果码→验证请求码和结果码是否匹配→验证成功→跳回主界面并获取到界面2返回的数据
Ⅴ、AVD模拟：
