java - 如何将 switch case 与字符串资源一起使用

Question

如何将 switch case 场景与字符串资源而不是硬编码名称一起使用？我的字符串与用于拼写的名称完全相同。

        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            MainListAdapter adapter = (MainListAdapter) parent.getAdapter();
            Main continent = adapter.getItem(position);
               if (mTwoPane) {
                    View rowView = view;
                    setItemSelected(continent, rowView);

                    Fragment newFragment;
                    switch (stringRes) {
                        case R.id.africa:
                            newFragment = new FragmentAfrica();
                            break;
                        case R.id.asia:
                            newFragment = new FragmentAsia();
                            break;
                        case R.id.europe:
                            newFragment = new FragmentEurope();
                            break;
                        default:
                            newFragment = new FragmentAfrica();
                    }

                    MainActivity activity = (MainActivity) view.getContext();
                    FragmentTransaction transaction = activity.getSupportFragmentManager().beginTransaction();
                    transaction.replace(R.id.detail_container, newFragment);
                    transaction.commit();
                } else {
              }

Answer 1

开关标签(即 case "africa": 中的 "africa")必须是 constant expressions根据 JLS § 14.12 .因此，如果您想使用 switch，您必须将字符串资源值存储在一个常量变量中，然后将该常量用作开关标签。

示例(使用类常量或局部常量):

class Example {
  public static final String CONTINENT_EUROPE =
      getResources().getString(R.string.europe);  // Option 1: class constants
  public static final String CONTINENT_NORTHERN_AMERICA =
      getResources().getString(R.string.northernAmerica);

  public void foo() {
    final String continentAfrica =
        getResources().getString(R.string.africa);  // Option 2: local constants
    final String continentAsia =
        getResources().getString(R.string.asia);
    switch (continent) {
    // Option 1:
    case continentAfrica:
      newFragment = new FragmentAfrica();
      break;
    case continentAsia:
      newFragment = new FragmentAsia();
      break;
    // Option 2:
    case CONTINENT_EUROPE:
      newFragment = new FragmentEurope();
      break;
    case CONTINENT_NORTHERN_AMERICA:
      newFragment = new FragmentNorthernAmerica();
      break;
    // ...
  }
}