android - onActivityResult() 未在 onBackPressed() 上触发

Question

我只是想在按下“后退”按钮时将对象信息从 Activity2 交换回 Activity1。一切正常，除了 Activity1 中的 onActivityResult(..) 永远不会被触发。 因此我无法访问 Intent 信息。谁知道为什么？

我检查了这些答案，但它们不起作用:

setResult does not work when BACK button pressed

How to pass data from 2nd activity to 1st activity when pressed back? - android

How to pass the values from one activity to previous activity

Send data to a parent activity onBackPressed

我的代码(如果你需要更多，告诉我):

AndroidManifest.xml:

        <activity
            android:name="com.example.Activity1"
            android:label="@string/app_name"
            android:theme="@style/AppTheme.NoActionBar"
            android:screenOrientation="portrait">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <activity
            android:name="com.example.Activity2"
            android:theme="@style/AppTheme.NoActionBar"
            android:screenOrientation="portrait">
        </activity>

Activity1.java:

public class MainActivity extends AppCompatActivity {

    // other stuff...

    private void showActivity2(Test test) {
        Intent intent = new Intent(this, Activity2.class);
        intent.putExtra("test", test.getSerializableObject());
        startActivityForResult(intent, Activity.RESULT_OK);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (resultCode == RESULT_CANCELED) {
            Test test = data.getExtras().getParcelable("test");
            // Do something...
        }
    }

Activity2.java:

public class Activity2 extends AppCompatActivity {

    // other stuff....

    @Override
    public void onBackPressed() {
        Intent intent = new Intent();
        intent.putExtra("test", test.getSerializableObject());
        setResult(Activity.RESULT_CANCELED, intent);
        super.onBackPressed();
    }
}

Answer 1

根据 startActivityForResult 的 android 文档

Same as calling startActivityForResult(Intent, int, Bundle) with no options.

intent Intent: The intent to start.

requestCode int: If >= 0, this code will be returned in onActivityResult() when the activity exits.

现在您所做的是:startActivityForResult(intent, Activity.RESULT_OK);

Activity.RESULT_OK实际值为 -1，这就是它不返回结果的原因。当您开始一个结果 Activity 时，您需要有一个有效的请求代码，然后在您的 onActivityResult 中过滤请求代码。