Stack Overflow对此问题的讨论这里
Save state in fragment
在Fragment里面,利用onSaveInstanceState保存数据,并可在onActivityCreated里面恢复数据。
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
...
if (savedInstanceState != null) {
// Restore the fragment's state here
}
}
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
// Save the fragment's state here
}
Save state in Activity
接下来重点是,在Activity里面,利用onSaveInstanceState保存Fragment实例的数据,并可在onCreate里面恢复数据。
private Fragment myFragment;
public void onCreate(Bundle savedInstanceState) {
...
if (savedInstanceState == null) {
// Instantiate fragment
} else {
// Restore the fragment's instance
myFragment = getSupportFragmentManager().getFragment(
savedInstanceState, "fragment");
}
...
}
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
//Save the fragment's instance
// fragment instance may be null
if (myFragment != null) {
getSupportFragmentManager().putFragment(outState, "fragment", myFragment);
}
}
End
最后,不要忽略状态保存的问题,在内存不足或者系统限制比较苛刻的机器上面,都有可能出现Fragment或Activity被回收,比如经常出现拍照之后返回App,但App里面的数据被清空了,更常见的就是旋转屏幕,所以要保存好自己需要的数据。
网友评论