Fragment学习之旅（三）

hide()、show()的使用

1、方法展示

//将指定的Fragment隐藏不显示
public FragmentTransaction hide(Fragment fragment);
//将以前隐藏过的Fragment显示出来
public FragmentTransaction show(Fragment fragment);

2、frag hide的代码：

FragmentManager manager = getsupportFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
Fragment fragment = manager.findFragmentByTag(tag);
transaction.hide(fragment);
transaction.addToBackStack(stackName);
transaction.commit();

4、frag show的代码：

FragmentManager manager = getSupportFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
Fragment fragment = manager.findFragmentByTag(tag);
transaction.show(fragment);
transaction.addToBackStack(stackName);
transaction.commit();

detach()、attach()的使用

1、detach()

detach()会将fragment和view分离，将fragment从Activity的ADD队列中移除。但是fragment实例依然存在，可以在FragmentManager中找到，通过方法FragmentManager的findFragmentByTag方法。
代码：

private void detachFrag(String tag, String stackName) {
        FragmentManager manager = getSupportFragmentManager();
        Fragment fragment = manager.findFragmentByTag(tag);
        FragmentTransaction transaction = manager.beginTransaction();
        transaction.detach(fragment);
        transaction.addToBackStack(stackName);
        transaction.commit();
}

2、attach()

这个方法和detach()的作用相反，它通过fragment的onCreatedView重建视图，然后添加到Activity的ADD队列中，attach时会将fragment添加到Activity的fragment队列的最顶层。
代码：

  private void attachFrag(String tag, String stackName) {
      FragmentManager manager = getSupportFragmentManager();
      Fragment fragment = manager.findFragmentByTag(tag);
      FragmentTransaction transaction = manager.beginTransaction();
      transaction.attach(fragment);
      transaction.addToBackStack(stackName);
      transaction.commit();
}

add()和replace()不要同时使用