只显示一个片段

Question

在我的应用程序中，我使用三个片段活动用于导航抽屉，但是在使用片段事务替换一个片段时，总是显示最后一个片段为什么？这是我的代码： -

public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
    Fragment fragment = new HomeFragment();
    Class fragmentClass = null;
    switch (position) {
        case 0:
            Log.d("position1", String.valueOf(position));
            fragmentClass = FarecardFragment.class;
        case 1:
            Log.d("position1", String.valueOf(position));
            fragmentClass = MybookingFragment.class;
        case 2:
            Log.d("position1", String.valueOf(position));
            fragmentClass = TrackingFragment.class;
    }
    try {
        fragment = (Fragment) fragmentClass.newInstance();
    } catch (Exception e) {
        e.printStackTrace();
    }
    FragmentManager fragmentManager = getFragmentManager();
    fragmentManager.beginTransaction().replace(R.id.mainContent, fragment).commit();
}

Answer 1

因为你永远不会破坏你的开关案例

  switch (position) {
      case 0:
         Log.d("position1", String.valueOf(position));
         fragmentClass = FarecardFragment.class;
         break;
      case 1:
         Log.d("position1", String.valueOf(position));
         fragmentClass = MybookingFragment.class;
         break;
      case 2:
         Log.d("position1", String.valueOf(position));
         fragmentClass = TrackingFragment.class;
         break;
}

break语句是必要的，因为没有它们，匹配的case标签之后的所有语句都会按顺序执行，而不管它们的case标签，直到遇到break语句或case结束。