[英]Android onSaveInstanceState is always null
请考虑以下方法:
@Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putSerializable("repertoire",rep);
}
我正在使用Android Studio生成的菜单NavigationDrawer
。 当我回到主要活动时,类中的savedInstanceState
始终为null
:
公共类MainActivity扩展ActionBarActivity实现NavigationNavigatorerFragment.NavigationDrawerCallbacks:
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if( savedInstanceState != null ) {
rep = (repertoire) savedInstanceState.getSerializable("repertoire");
}
setContentView(R.layout.activity_main);
mNavigationDrawerFragment = (NavigationDrawerFragment) getSupportFragmentManager().findFragmentById(R.id.navigation_drawer);
mTitle = getTitle();
ListView vue = (ListView) findViewById(R.id.listView);
if(rep==null){
rep = new repertoire();
}
// Set up the drawer.
mNavigationDrawerFragment.setUp(
R.id.navigation_drawer,
(DrawerLayout) findViewById(R.id.drawer_layout));
}
我不确定100%,但是您不应该在onRestoreInstanceState()中恢复活动吗? 同样,我不是100%肯定,但它可能有效。
继续创建它!
@Override
public void onSaveInstanceState(Bundle outState) {
if (outState == null) {
outState = new Bundle();
}
outState.putSerializable("repertoire", rep);
super.onSaveInstanceState(outState);
}
除非将非null Bundle
传递给super方法,并且super方法只是一个存根,否则super方法不会执行任何操作! 视图层次结构是单独保存的。 现在,您将在onCreate(Bundle)
和onRestoreInstanceState(Bundle)
中将Bundle
作为参数接收。
我当前的代码:在onCreate中:
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if( savedInstanceState != null ) {
System.out.println("back");
rep = (repertoire) savedInstanceState.getSerializable("repertoire");
}
和:
@Override
public void onSaveInstanceState(Bundle outState) {
System.out.println("bibi");
if (outState == null) {
outState = new Bundle();
}
super.onSaveInstanceState(outState);
outState.putSerializable("repertoire", rep);
}
@Override
public void onRestoreInstanceState(Bundle bundle){
System.out.println("okm");
super.onRestoreInstanceState(bundle);
bundle.putSerializable("repertoire",rep);
}
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