Android StartActivityForResult的简单使用

public class MainActivity extends Activity {

private TextView tv;
private Button btn;
private int REQUESTCODE=1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

tv = (TextView) findViewById(R.id.activity_main_tv);
btn = (Button) findViewById(R.id.activity_main_btn);

btn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Intent intent=new Intent();
intent.setClass(MainActivity.this, TestActivity.class);
//简单的intent传值
intent.putExtra("key", "小白");
startActivityForResult(intent,REQUESTCODE);

}
});
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {

super.onActivityResult(requestCode, resultCode, data);
if(requestCode==REQUESTCODE&&resultCode==RESULT_OK){
if(data!=null){
String extra = data.getStringExtra("key");
tv.setText(extra);
}
}

}

}

public class TestActivity extends Activity{

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

tv = (TextView) findViewById(R.id.activity_main_tv);
Intent intent = getIntent();
String stringExtra = intent.getStringExtra("key");
tv.setText(stringExtra);

Intent intent1=new Intent();
intent1.putExtra("key", "小黑");
setResult(RESULT_OK, intent);
}
}