我很难让我的应用持久化。当我旋转手机时，屏幕上的数据不会改变。但是在我单击一个按钮以检索一个新片段后，我收到一条错误消息“在 onSaveInstanceState 之后无法执行此操作”。我用谷歌搜索并看到了类似的问题，但我仍然不知道如何处理和解决这个问题。
我有一个活动类、一个控制器类和两个片段类。活动类有一个带有 2 个按钮的导航查看器，用于触发片段事务。也就是说，在每次单击按钮时，它将用按钮侦听器中设置的片段替换当前片段。我的控制器类初始化系统，片段只是 UI。
我的活动课：
public class LoggedInActivity extends AppCompatActivity {
private final String TAG = "LoggedInActivity: ";
private Controller controller;
private TextView navName;
private NavigationView navigationView;
@Override
protected void onCreate(Bundle savedInstanceState) {
Log.v(TAG, "onCreate");
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_logged_in);
if(savedInstanceState == null) {
Log.v(TAG, "savedInstanceState == null");
initComponents();
setNavName();
initListener();
initializeSystem();
} else {
Log.v(TAG, "savedInstanceState != null");
initComponents();
setNavName();
initListener();
this.controller = (Controller)savedInstanceState.getSerializable("controller");
}
}
private void initComponents() {
navigationView = (NavigationView) findViewById(R.id.navigation_view);
View headerView = navigationView.getHeaderView(0);
navName = (TextView) headerView.findViewById(R.id.tv_name_surname);
}
private void initListener() {
navigationView.setNavigationItemSelectedListener(new MyNavigationItemListener());
}
private void initializeSystem() {
Log.v(TAG, "new controller");
controller = new Controller(this, null);
}
public void setFragment(Fragment fragment) {
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.fragment_container_logged_in, fragment).commit();
}
private class MyNavigationItemListener implements NavigationView.OnNavigationItemSelectedListener {
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
switch(item.getItemId()) {
case R.id.drawer_summary:
controller.setFragmentSummary();
break;
case R.id.drawer_income:
controller.setFragmentIncome();
break;
}
return false;
}
}
@Override
protected void onSaveInstanceState(Bundle outState) {
outState.putSerializable("controller", controller);
super.onSaveInstanceState(outState);
Log.v(TAG, "onSaveInstanceState, saving the controller");
}
}
我的控制器类：
public class Controller implements Serializable {
private final String TAG = "Controller: ";
/********************** Fragments ***********************/
private Fragment_Income fragment_income;
private Fragment_Summary fragment_summary;
/********************************************************/
/********************** Activities **********************/
private LoggedInActivity logged_in_activity;
/********************************************************/
public Controller(LoggedInActivity logged_in_activity) {
this.logged_in_activity = logged_in_activity;
initLoggedInFragments();
setFragmentSummary();
}
}
/* Initializes fragments that are connected to LoggedInActivity */
private void initLoggedInFragments() {
fragment_income = new Fragment_Income();
fragment_income.setController(this);
fragment_summary = new Fragment_Summary();
fragment_summary.setController(this);
}
/* use to replace current fragment with the given one */
private void replaceFragmentWith(Fragment fragment) {
logged_in_activity.setFragment(fragment);
}
/***********************************************************
* METHODS REGARDING FRAGMENT INCOME *
**********************************************************/
public void setFragmentIncome() {
replaceFragmentWith(fragment_income);
}
/* Summary fragment is started at first */
public void setFragmentSummary() {
replaceFragmentWith(fragment_summary);
}
}
片段_收入：
public class Fragment_Income extends Fragment implements Serializable{
private final String TAG = "Fragment_Income: ";
private Controller controller;
private FloatingActionButton fab_income;
private ListView lv_income;
private ArrayList<LvData> incomeData;
private LvAdapterIncome lvAdapterIncome;
public Fragment_Income() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
Log.v(TAG, "onCreateView");
View view = inflater.inflate(R.layout.fragment_income, container, false); // Inflate the layout for this fragment
if(savedInstanceState != null) {
this.controller = (Controller) savedInstanceState.getSerializable("controller");
}
initComponents(view);
initListener();
setupListView();
return view;
}
private void initComponents(View view) {
fab_income = (FloatingActionButton) view.findViewById(R.id.fab_income);
lv_income = (ListView) view.findViewById(R.id.lv_income);
}
private void initListener() {
ButtonListener buttonListener = new ButtonListener();
fab_income.setOnClickListener(buttonListener);
}
private void setupListView() {
if (incomeData == null) { // checks if incomeData have been initalized before, if so do not change array to defualt
incomeData = new ArrayList<>();
lvAdapterIncome = new LvAdapterIncome(getContext(), incomeData);
}
lv_income.setAdapter(lvAdapterIncome);
}
public void setController(Controller controller) {
this.controller = controller;
}
@Override
public void onSaveInstanceState(Bundle outState) {
Log.v(TAG, "onSaveInstanceState, saving the controller");
outState.putSerializable("controller", this.controller);
super.onSaveInstanceState(outState);
}
}
片段_摘要：
public class Fragment_Summary extends Fragment implements Serializable {
private static final String TAG = "Fragment_Summary: ";
private Controller controller;
private TextView tv_user;
private TextView tv_total_revenue;
private TextView tv_total_expenditure;
private TextView tv_balance;
private float totalRevenue;
private float totalExpenditure;
private float balance;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_summary, container, false);// Inflate the layout for this fragment
initComponents(view);
setUserName();
if(savedInstanceState == null) {
//DO SOMETHING
}
return view;
}
private void addData() {
totalRevenue = controller.getTotalRevenue();
totalExpenditure = controller.getTotalExpenditure();
balance = totalRevenue - totalExpenditure;
tv_total_revenue.setText(String.valueOf(totalRevenue));
tv_total_expenditure.setText(String.valueOf(totalExpenditure));
tv_balance.setText(String.valueOf(balance));
}
private void initComponents(View view) {
tv_user = (TextView)view.findViewById(R.id.tv_user);
tv_total_revenue = (TextView)view.findViewById(R.id.tv_revenue);
tv_total_expenditure = (TextView)view.findViewById(R.id.tv_sum_exp);
tv_balance = (TextView)view.findViewById(R.id.tv_balance);
}
@Override
public void onSaveInstanceState(Bundle outState) {
outState.putString("revenue", String.valueOf(balance));
outState.putString("totalExpenditure", String.valueOf(balance));
outState.putString("balance", String.valueOf(balance));
super.onSaveInstanceState(outState);
}
public void setController(Controller controller) {
this.controller = controller;
}
}
我已经从我的类中删除了所有头文件和一些方法，因为我认为它们与这个问题无关。
这是错误日志：
java.lang.IllegalStateException: Can not perform this action after onSaveInstanceState
at android.app.FragmentManagerImpl.checkStateLoss(FragmentManager.java:1434)
at android.app.FragmentManagerImpl.enqueueAction(FragmentManager.java:1452)
at android.app.BackStackRecord.commitInternal(BackStackRecord.java:708)
at android.app.BackStackRecord.commit(BackStackRecord.java:672)
at com.example.user.my_app.LoggedInActivity.setFragment(LoggedInActivity.java:85)
at com.example.user.my_app.Controller.replaceFragmentWith(Controller.java:89)
at com.example.user.my_app.Controller.setFragmentIncome(Controller.java:99)
at com.example.user.my_app.LoggedInActivity$MyNavigationItemListener.onNavigationItemSelected(LoggedInActivity.java:127)
at android.support.design.widget.NavigationView$1.onMenuItemSelected(NavigationView.java:156)
at android.support.v7.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:822)
at android.support.v7.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:156)
at android.support.v7.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:969)
at android.support.design.internal.NavigationMenuPresenter$1.onClick(NavigationMenuPresenter.java:342)
at android.view.View.performClick(View.java:5637)
at android.view.View$PerformClick.run(View.java:22429)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)