默认情况下保存的片段是savedInstanceState？ [英] Are fragments saved by default with savedInstanceState?

问题描述

我阅读了什么是onCreate（Bundle savedInstanceState）
onsaveinstancestate为您提供捆绑以前的应用程序状态（如果屏幕的方向改变了。

I read on What's onCreate(Bundle savedInstanceState) that onsaveinstancestate gives you a bundle of the previous state of the application(if the orientation of the screen changed.

我看了Android文档（ http://developer.android.com/training/basics/activity-lifecycle/recreating.html ），并看到您必须手动将要保存的值作为键值对，他们的代码是

I looked on the Android docs(http://developer.android.com/training/basics/activity-lifecycle/recreating.html) and saw that you have to manually put the values you want saved as key value pairs. Their code for doing so was

    static final String STATE_SCORE = "playerScore";
static final String STATE_LEVEL = "playerLevel";
...

@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
    // Save the user's current game state
    savedInstanceState.putInt(STATE_SCORE, mCurrentScore);
    savedInstanceState.putInt(STATE_LEVEL, mCurrentLevel);

我的问题是片段，当方向更改和活动重新创建时，是否自动重新连接？你要把代码保存成捆绑包吗？
对于我想要了解的这种情况，对于这种情况来说，这是一个Facebook代码。

My question is for fragments, are they automatically reattached when the orientation changes and the activity recreated? Would you have to put code to save it into a bundle? Heres facebook code for this situation that I am trying to understand

 @Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

if (savedInstanceState == null) {
    // Add the fragment on initial activity setup
    mainFragment = new MainFragment();
    getSupportFragmentManager()
    .beginTransaction()
    .add(android.R.id.content, mainFragment)
    .commit();
} else {
    // Or set the fragment from restored state info
    mainFragment = (MainFragment) getSupportFragmentManager()
    .findFragmentById(android.R.id.content);
}

}

推荐答案

为了在活动被破坏时保留一个片段，所以它会自动重新绘制，你应该调用

To keep a fragment when an Activity gets destroyed, so it automatically reataches, you should call

Fragment.setRetainInstance(true)

默认情况下， onSaveInstanceState（）

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