startActivityForResult用法

在FirstActivity中启动SecondActivity，并且当关闭SecondActivity时，FirstActivity会接收SecondActivity传递的参数。

FirstActivity中：

private static final int REQUEST_CODE = 100;
Intent intent = new Intent(this, SecondActivity.class);
startActivityForResult(intent, REQUEST_CODE);

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
  if (data == null) {
    return;
  }
  if (REQUEST_CODE == requestCode && RESULT_OK == resultCode) {
    String value = data.getStringExtra("key");
    if (!TextUtils.isEmpty(value)) {
      Log.i(TAG, "value=" + value);
    }
  }
  super.onActivityResult(requestCode, resultCode, data);
}

SecondActivity中：

Intent intent = new Intent(this, FirstActivity.class);
intent.putExtra("key", "value");
setResult(RESULT_OK, intent);
finish();