Android优化之切换Fragment

//错误的做法
//每次切换的时候，Fragment都会重新实例化，重新加载一边数据，这样非常消耗性能和用户的数据流量
public void switchFragment(Fragment targetFragment) {
    if (targetFragment == null)
      return;
    FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
    //目标Fragment替换原来的Fragment
    transaction.replace(R.id.content, targetFragment);
    transaction.commit();
  }

//正确的做法
private void switchFragment(Fragment targetFragment) {
    FragmentTransaction transaction = getSupportFragmentManager()
            .beginTransaction();
    if (!targetFragment.isAdded()) {
        transaction
                .hide(currentFragment)
                .add(R.id.main_fragment, targetFragment)
                .commit();
        System.out.println("还没添加呢");
    } else {
        transaction
                .hide(currentFragment)
                .show(targetFragment)
                .commit();
        System.out.println("添加了( ⊙o⊙ )哇");
    }
    currentFragment = targetFragment;
}