java - get SavedInstanceState() 和 onViewStateRestored() bundle 的问题

Question

我的 Activity 中有一个 Fragment，当设备旋转时，会调用 onSaveInstanceState() 和 onViewStateRestored()。

onSaveInstanceState():

@Override
public void onSaveInstanceState(Bundle outState){
    Log.e("Fragment", "Called onSaveInstanceState");

    outState = getSavedInstanceState();

    super.onSaveInstanceState(outState);
}

这就是在 onSaveInstanceState() 中设置 outState 包的内容:

public static Bundle getSavedInstanceState(){
    Bundle saveState = new Bundle();

    //Save view states
    saveState.putBoolean("startButtonVisible", buttonStart.getVisibility() == View.VISIBLE);
    saveState.putBoolean("stopButtonVisible", buttonStop.getVisibility() == View.VISIBLE);
    saveState.putBoolean("resetButtonVisible", buttonReset.getVisibility() == View.VISIBLE);
    saveState.putBoolean("saveButtonVisible", buttonSave.getVisibility() == View.VISIBLE);
    saveState.putBoolean("openLatestFileButtonVisible", buttonOpenLatestFile.getVisibility() == View.VISIBLE);

    saveState.putBoolean("editTextStartValueVisible", editTextStartValue.isEnabled());
    saveState.putBoolean("buttonStartValueDownVisible", buttonStartValueDown.isEnabled());
    saveState.putBoolean("buttonStartValueUpVisible", buttonStartValueUp.isEnabled());
    saveState.putBoolean("editTextEndValueVisible", editTextEndValue.isEnabled());
    saveState.putBoolean("buttonEndValueDownVisible", buttonEndValueDown.isEnabled());
    saveState.putBoolean("buttonEndValueUpVisible", buttonEndValueUp.isEnabled());

    return saveState;
}

这可以正确保存数据，但是当调用 onViewStateRestored() 时，数据不正确。

@Override
public void onViewStateRestored(Bundle savedInstanceState){
    Log.e("Fragment", "Called onViewStateRestored");

    super.onViewStateRestored(savedInstanceState);

    //Restore view states
    if (savedInstanceState != null){

        restoreInstanceState(savedInstanceState);

        if (buttonReset.getVisibility() == View.VISIBLE){
            updateUi();
        }
    }
}

当调用onViewStateRestored()时，它还会调用restoreInstanceState()，这应该是恢复每个 View 的状态。

public static void restoreInstanceState(Bundle savedInstanceState){
    buttonStart.setVisibility(savedInstanceState.getBoolean("startButtonVisible") ? View.VISIBLE : View.INVISIBLE);
    buttonStop.setVisibility(savedInstanceState.getBoolean("stopButtonVisible") ? View.VISIBLE : View.INVISIBLE);
    buttonReset.setVisibility(savedInstanceState.getBoolean("resetButtonVisible") ? View.VISIBLE : View.INVISIBLE);
    buttonSave.setVisibility(savedInstanceState.getBoolean("saveButtonVisible") ? View.VISIBLE : View.INVISIBLE);
    buttonOpenLatestFile.setVisibility(savedInstanceState.getBoolean("openLatestFileButtonVisible") ? View.VISIBLE : View.INVISIBLE);

    editTextStartValue.setEnabled(savedInstanceState.getBoolean("editTextStartValueVisible"));
    buttonStartValueDown.setEnabled(savedInstanceState.getBoolean("buttonStartValueDownVisible"));
    buttonStartValueDown.setImageResource(buttonStartValueDown.isEnabled() ? R.drawable.ic_arrow_down : R.drawable.ic_arrow_down_gray);
    buttonStartValueUp.setEnabled(savedInstanceState.getBoolean("buttonStartValueUpVisible"));
    buttonStartValueUp.setImageResource(buttonStartValueUp.isEnabled() ? R.drawable.ic_arrow_up : R.drawable.ic_arrow_up_gray);
    editTextEndValue.setEnabled(savedInstanceState.getBoolean("editTextEndValueVisible"));
    buttonEndValueDown.setEnabled(savedInstanceState.getBoolean("buttonEndValueDownVisible"));
    buttonEndValueDown.setImageResource(buttonEndValueDown.isEnabled() ? R.drawable.ic_arrow_down : R.drawable.ic_arrow_down_gray);
    buttonEndValueUp.setEnabled(savedInstanceState.getBoolean("buttonEndValueUpVisible"));
    buttonEndValueUp.setImageResource(buttonEndValueUp.isEnabled() ? R.drawable.ic_arrow_up : R.drawable.ic_arrow_up_gray);

    Log.e("Fragment", "Restored view visibility");
}

为什么调用onViewStateRestored()时数据不正确？所有 View 都变得不可见，无论它们之前是什么。保存和恢复状态时的包是否不一样？

但是，在调用 fragmentManager.beginTransaction().replace(R.id.content_frame, CustomFragmentManager.savedFilesFragment).commit(); 时，所有这些代码都可以工作。然后手动调用onViewStateRestored()。

编辑:更改了字段名称。

解决方案:我已替换 outState = new Bundle(getSavedInstanceState());与 outState.putAll(getSavedInstanceState());现在它正在发挥作用。调用setRetainInstance(true);没有必要。

Answer 1

您不应该使用已传入 onSaveInstanceState() 方法并在 onCreate() 方法中恢复的 outState 对象自行手动创建状态包。另外，您应该在 fragment 的 onCreate() 中调用 setRetainInstance(true)。