android - 从菜单项中选择一个是要进行的 Activity ，我怎样才能在 android 中直接进行 Activity

Question

Activity main 包含在 cade 下面，一切正常，但是当我从抽屉注销时，我想去 Activity instand fragment，如果我放 break;如果注销比 fragment 类不解决。

 public void selectDrawerItem(MenuItem menuItem) {
    Fragment fragment = null;
    Class fragmentClass;
    Float elevation =   getResources().getDimension(R.dimen.elevation_toolbar);

    switch (menuItem.getItemId()) {

        case R.id.home:
            fragmentClass = HomeFragment_.class;
            break;
        case R.id.process:
            fragmentClass = ProcessFragment_.class;
            break;
        case R.id.decline:
            fragmentClass = RejectFragment_.class;
            break;

        case R.id.more:
            try {
                 startActivity(new Intent(
                        Intent.ACTION_VIEW,
                        Uri.parse("https://play.google.com/store/search?q=mndigital")));
            } catch (android.content.ActivityNotFoundException anfe) {
                startActivity(new Intent(
                        Intent.ACTION_VIEW,
                        Uri.parse("https://play.google.com/store/search?q=mndigital")));
            }
                fragmentClass = HomeFragment_.class;
            break;
        case R.id.logout:
            VPreferences.reset();
            Intent intent = new     Intent(MainActivity.this,LoginActivity_.class);
            startActivity(intent);
            finish();
  //                fragmentClass = HomeFragment_.class;
 //                break;
          default:
            fragmentClass = HomeFragment_.class;
            break;
    }
    try {
        fragment = (Fragment) fragmentClass.newInstance();
    } catch (InstantiationException e) {
        e.printStackTrace();
    } catch (IllegalAccessException e) {
        e.printStackTrace();
    }

      FragmentManager fragmentManager = getSupportFragmentManager();
    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

    fragmentTransaction.replace(R.id.content_frame, fragment);
    fragmentTransaction.addToBackStack(null);
    fragmentTransaction.commit();


    menuItem.setChecked(true);
    setTitle(menuItem.getTitle());

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP)
        toolbar.setElevation(0.0f);

    drawerLayout.closeDrawers();
}

当我从抽屉登录 Activity 中单击注销时，打开我如何到达。

Answer 1

您需要在 case R.id.logout: 之后放置一个break。

当 case 是 R.id.logout 时，它也会转到 default case。

编写 finish() 不会立即终止 Activity ，而是在完成之前完成该线程中的其他未决指令。

或者您可以在启动 LoginActivity_ 之后，从开关 block 返回控制流。

case R.id.logout:
            VPreferences.reset();
            Intent intent = new     Intent(MainActivity.this,LoginActivity_.class);
            startActivity(intent);
            finish();
            break; // to make sure it doesn't go in the default block
            return; // to return the flow of control outside the switch statement