android - 以编程方式返回到上一个 fragment

Question

如何让 onBackPressed() 从每个 fragment 继续 HomeFragment 或转到上一个 fragment 。

这是默认情况下设置 fragment 的代码 Home fragment 在应用程序启动时打开但在返回时按下应用程序关闭。需要帮助解决，谢谢这是我的 MainActivityDrawer 类

private Toolbar mToolbar;
private FragmentDrawer drawerFragment;
GpsTrackerAlarmReceiver alarm = new GpsTrackerAlarmReceiver();
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main_drawer);

    mToolbar = (Toolbar) findViewById(R.id.toolbar);

    setSupportActionBar(mToolbar);
    getSupportActionBar().setDisplayShowHomeEnabled(true);

    drawerFragment = (FragmentDrawer)
    getSupportFragmentManager().findFragmentById(R.id.fragment_navigation_drawer);
    drawerFragment.setUp(R.id.fragment_navigation_drawer, (DrawerLayout) findViewById(R.id.drawer_layout), mToolbar);
    drawerFragment.setDrawerListener(this);
    alarm.setAlarm(this);

    // display the first navigation drawer view on app launch
    displayView(0);
}
        @Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    int id = item.getItemId();
    //noinspection SimplifiableIfStatement
    if (id == R.id.action_help) {
        return true;
    }
    if(id == R.id.action_search){
        Toast.makeText(getApplicationContext(), "Search action is selected!", Toast.LENGTH_SHORT).show();
        return true;
    }

    return super.onOptionsItemSelected(item);
}
@Override
public void onDrawerItemSelected(View view, int position) {
    displayView(position);
}
private void displayView(int position) {
    Fragment fragment = null;
    String title = getString(R.string.app_name);
    switch (position) {

        case 0:
            fragment = new HomeFragment();
            title = getString(R.string.title_home);
            break;
        case 1:
            fragment = new ProfileFragment();
            title = getString(R.string.title_profile);
            break;
        case 2:

            fragment = new ContactsFragment();
            title = getString(R.string.title_contacts);
            break;
        case 3:
            fragment = new GeoFencFragment();
            title = getString(R.string.title_geofence);
            break;
        case 4:
            fragment = new HistoryFragment();
            title = getString(R.string.title_history);
            break;
        case 5:
            fragment = new SettingFragment();
            title = getString(R.string.title_settimg);
            break;
        default:
            break;
    }
    if (fragment != null) {
        FragmentManager fragmentManager = getSupportFragmentManager();
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
        fragmentTransaction.replace(R.id.container_body, fragment);
        fragmentTransaction.commit();
        // set the toolbar title
        getSupportActionBar().setTitle(title);
    }
}
@Override
public void onResume() {
    Log.d(TAG, "onResume");
    super.onResume();
}
@Override
protected void onStop() {
    super.onStop();
}}

Answer 1

试试这个

getFragmentManager().beginTransaction().
    remove(this).commit();

或使用popBackStackImmediate()

在 commit() 之前使用 addToBackstack()。在您的 Activity 中

当你想删除 fragment 时使用popBackStackImmediate()