如何实现 Android ActionBar 后退按钮？

android java android-3.0-honeycomb

2022-08-31 07:41:36

我有一个列表视图的活动。当用户单击该项目时，项目“查看器”将打开：

List1.setOnItemClickListener(new OnItemClickListener() {
    @Override
    public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,long arg3) {

        Intent nextScreen = new Intent(context,ServicesViewActivity.class);
        String[] Service = (String[])List1.getItemAtPosition(arg2);

        //Sending data to another Activity
        nextScreen.putExtra("data", datainfo);
        startActivityForResult(nextScreen,0);
        overridePendingTransition(R.anim.right_enter, R.anim.left_exit);
    }
});

这工作正常，但在操作栏上，应用图标旁边的后退箭头未激活。我错过了什么吗？

答案 1

塞尔文已经发布了正确的答案。这里，漂亮的代码中的解决方案：

public class ServicesViewActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // etc...
        getActionBar().setDisplayHomeAsUpEnabled(true);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
        case android.R.id.home:
            NavUtils.navigateUpFromSameTask(this);
            return true;
        default:
            return super.onOptionsItemSelected(item);
        }
    }
}

该函数要求您在 AndroidManifest 文件中定义父活动.xmlNavUtils.navigateUpFromSameTask(this)

<activity android:name="com.example.ServicesViewActivity" >
    <meta-data
     android:name="android.support.PARENT_ACTIVITY"
     android:value="com.example.ParentActivity" />
</activity>

有关进一步阅读，请参阅此处。

答案 2

确保您在“活动”中启用了“操作栏”主页按钮：

Android， API 5+：

@Override
public void onBackPressed() {
     ...
     super.onBackPressed();
}

ActionBarSherlock and App-Compat， API 7+：

@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
    ...
    getSupportActionBar().setDisplayHomeAsUpEnabled(true);
}

Android， API 11+：

@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
    ...
    getActionBar().setDisplayHomeAsUpEnabled(true);
}

扩展的示例：MainActivityActionBarActivity

public class MainActivity extends ActionBarActivity {
    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // Back button
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
        case android.R.id.home: 
            // API 5+ solution
            onBackPressed();
            return true;

        default:
            return super.onOptionsItemSelected(item);
        }
    }
}

这样，您想要的所有活动都可以进行反冲。

Android， API 16+：

http://developer.android.com/training/implementing-navigation/ancestral.html

AndroidManifest.xml:

<application ... >
    ...
    <!-- The main/home activity (it has no parent activity) -->
    <activity
        android:name="com.example.myfirstapp.MainActivity" ...>
        ...
    </activity>
    <!-- A child of the main activity -->
    <activity
        android:name="com.example.myfirstapp.DisplayMessageActivity"
        android:label="@string/title_activity_display_message"
        android:parentActivityName="com.example.myfirstapp.MainActivity" >
        <!-- The meta-data element is needed for versions lower than 4.1 -->
        <meta-data
            android:name="android.support.PARENT_ACTIVITY"
            android:value="com.example.myfirstapp.MainActivity" />
    </activity>
</application>

扩展的示例：MainActivityActionBarActivity

public class MainActivity extends ActionBarActivity {
    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // Back button
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
        // Respond to the action bar's Up/Home button
        case android.R.id.home:
            NavUtils.navigateUpFromSameTask(this);
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}