savedInstanceState不為null，但沒有數據

Question

我有一個片段活動，在該活動中，我導航到搜索頁面，然后返回結果列表。 有時需要重新創建活動，因此我像這樣保存實例數據：

@Override
public void onSaveInstanceState(Bundle outState) {

    super.onSaveInstanceState(outState);

    System.out.println("Saving instance state!");

    // Save the instance data
    // Filter data
    Intent mIntent = new Intent(this, BasicMapDemoActivity.class);
    filter.addFilterToIntent(mIntent);
    outState = mIntent.getExtras();

    // Save date data
    int year = currentDate.getYear();
    int month = currentDate.getMonth();
    int day = currentDate.getDay();
    outState.putInt("YEAR",year);
    outState.putInt("MONTH",month);
    outState.putInt("DAY",day);

    // Location data
    double latitude = mapLocation.latitude;
    double longitude = mapLocation.longitude;
    outState.putDouble("LATITUDE",latitude);
    outState.putDouble("LONGITUDE",longitude);

    // Other
    outState.putString("VIEW_MODE",viewMode.toString());
    outState.putString("SORT_TYPE",sortType);
    outState.putInt("ZOOM", mapZoom);
}

然后，我嘗試還原onCreate中的數據，但是當我到達那里時，捆綁包不為null，但是它不包含我保存到其中的任何數據。 以下所有get函數均返回零（在上述代碼塊的末尾，我確認數據為非零）：

Override
protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);

    // If we are 're-creating', then get the old instance data, otherwise set defaults
    if(savedInstanceState == null)
    {
        // Set up default instance data
        currentDate = new Date(115,4,1);
        filter = new ObajoFilter();
        filter.start = currentDate;
        filter.end = new Date(115,4,1,23,59,0);
        viewMode = ViewMode.MAP;
        sortType = "Distance";
        mapLocation = userLocation;
        mapZoom = 16;

    } else {

        // Get date data
        int year = savedInstanceState.getInt("YEAR");
        int month = savedInstanceState.getInt("MONTH");
        int day = savedInstanceState.getInt("DAY");
        currentDate = new Date(year,month,day);

關於什么可以清空捆綁包的任何想法？ 據我了解，僅當應用程序完全銷毀后，savevedInstanceData才為空。

Answer 1

由於這一行， 所以outState = mIntent.getExtras（）;

您的outState指向不同的地址mIntent.getExtras（） ，因此為空

您應該直接使用outState.putXX而不創建新對象。

Answer 2

您是否要在onSaveInstanceState存儲要保留的信息，如下所示

@Override
public void onSaveInstanceState(Bundle outState) {
    outState.putParcelable("someobject", someobject);
    outState.putBoolean("someboolean", someBoolean);
    outState.putInt("someint", someInt);
    super.onSaveInstanceState(outState);
}