Android:Nav Drawer 后退按钮无法完成应用程序

Question

我正在开发使用抽屉导航的应用程序。不幸的是我不知道，当用户在主屏幕上按下后退按钮时，我该如何完成这个应用程序？我试图覆盖后退按钮并在那里完成我的 Activity ，但这不起作用。 Activity 周而复始..

我正在尝试更多示例，例如:

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if ((keyCode == KeyEvent.KEYCODE_BACK)) {
        finish();
    }
    return super.onKeyDown(keyCode, event);
}

或覆盖

 @Override
    public void onBackPressed() {            
        finish();
    }

//编辑这是我的主要 Activity 代码，其中大部分是由 Android Studio 生成的:

public class MainActivity extends ActionBarActivity
        implements NavigationDrawerFragment.NavigationDrawerCallbacks {

    /**
     * Fragment managing the behaviors, interactions and presentation of the navigation drawer.
     */
    private NavigationDrawerFragment mNavigationDrawerFragment;

    /**
     * Used to store the last screen title. For use in {@link #restoreActionBar()}.
     */
    private CharSequence mTitle;

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

        mNavigationDrawerFragment = (NavigationDrawerFragment)
                getSupportFragmentManager().findFragmentById(R.id.navigation_drawer);
        mTitle = getTitle();

        // Set up the drawer.
        mNavigationDrawerFragment.setUp(
                R.id.navigation_drawer,
                (DrawerLayout) findViewById(R.id.drawer_layout));
    }

    @Override
    public void onNavigationDrawerItemSelected(int position, boolean fromSavedInstanceState) {
        // update the main content by replacing fragments
        FragmentManager fragmentManager = getSupportFragmentManager();
        fragmentManager.beginTransaction()
                .replace(R.id.container, EmailListFragment.newInstance(position))
                .commit();
    }

    public void onSectionAttached(int number) {
        switch (number) {
            case 1:
                mTitle = getString(R.string.title_section1);
                break;
            case 2:
                mTitle = getString(R.string.title_section2);
                break;
            case 3:
                mTitle = getString(R.string.title_section3);
                break;
        }
    }

    public void restoreActionBar() {
        ActionBar actionBar = getSupportActionBar();
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
        actionBar.setDisplayShowTitleEnabled(true);
        actionBar.setTitle(mTitle);
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        if (!mNavigationDrawerFragment.isDrawerOpen()) {
            // Only show items in the action bar relevant to this screen
            // if the drawer is not showing. Otherwise, let the drawer
            // decide what to show in the action bar.
            getMenuInflater().inflate(R.menu.main, menu);
            restoreActionBar();
            return true;
        }
        return super.onCreateOptionsMenu(menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    /**
     * Should close application when back button is pressed, but  doesn't work yet
     *
     * @param keyCode
     * @param event
     * @return
     */
    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if ((keyCode == KeyEvent.KEYCODE_BACK)) {
            this.onDestroy();
            finish();
        }
        return super.onKeyDown(keyCode, event);
    }
}

Answer 1

我认为代码没有任何问题 - 这是有道理的，因为大部分代码来自模板 - 除了我建议使用 onDestroy。它必须是 Android Studio。我会尝试旁加载 APK 或创建一个新项目并复制代码。如果这些都不起作用，那一定是一个错误。由于它必须在 Activity 中，我会尝试扩展 Activity 而不是 ActionBarActivity(这将您限制为 SDK v14+)，因为这样可以避免使用支持库，从问题中删除变量。