SavedInstanceState为空

Question

我想在与其他设备“同步”时获取当前系统时间。因此，此活动通常在同步后调用/显示。

目前，当前系统时间是正确的，但我也有警报弹出另一个活动，一旦我完成了该活动，我想回到此活动。一旦我这样做，系统时间会更新到最新的时间，而不是旧的当前时间（这正是我想要的）。

我试图使用SavedInstanceState保存旧的当前时间的状态，并且它确实在onSavedInstanceState中获得正确的字符串。当我回到此活动时，SavedInstanceState为空。我不知道为什么？

public class InfoActivity extends BaseActivity { 

String fileLastSync = null; 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 

     super.onCreate(savedInstanceState); 
     setContentView(R.layout.info); 
     Resources resources = context.getResources(); 

     if (savedInstanceState != null) { 
      // Restore value of members from saved state 
      fileLastSync = savedInstanceState.getString("FileLastSync"); 
     } else { 
      //Gets the current DateTime 
      long nextTime = (System.currentTimeMillis()); 
      Date date = new Date(nextTime); 

      //Formats the current DateTime 
      SimpleDateFormat format = new SimpleDateFormat("MM-dd-yyyy HH:mm a"); 
      String formatDate = format.format(date); 

      //Last sync time is the current formatted date 
      fileLastSync = formatDate; 
     } 

     //Gets the 'last synced' string and sets to datetime of the last sync 
     String syncString = String.format(resources.getString(R.string.last_sync), fileLastSync); 

     //Dynamically sets the datetime of the last sync string 
     TextView lastSyncTextView = ((TextView) findViewById(R.id.last_sync)); 
     lastSyncTextView.setText(syncString); 
} 

    @Override 
    protected void onSaveInstanceState(Bundle savedInstanceState) { 

     savedInstanceState.putString("FileLastSync",fileLastSync); 
     super.onSaveInstanceState(savedInstanceState); 
    } 

@Override 
protected void onRestoreInstanceState(Bundle savedInstanceState) { 
    super.onRestoreInstanceState(savedInstanceState); 
    if (savedInstanceState != null) { 
     // Restore value of members from saved state 
     fileLastSync = savedInstanceState.getString("FileLastSync"); 
    } else { 
     //Gets the current DateTime 
     long nextTime = (System.currentTimeMillis()); 
     Date date = new Date(nextTime); 

     //Formats the current DateTime 
     SimpleDateFormat format = new SimpleDateFormat("MM-dd-yyyy hh:mm a"); 
     String formatDate = format.format(date); 

     //Last sync time is the current formatted date 
     fileLastSync = formatDate; 

    } 

} 

} 

编辑：我试图把这个：super.onSaveInstanceState(savedInstanceState);在方法的结束，但仍然无法正常工作。

Answer 1

您不应该将onSave中的相同代码放入onRestore中。相反，将完整的if语句从onCreate方法复制到onRestore方法中。并以super.onRestoreInstanceState作为第一条语句。

编辑：对不起 - 本意是发表评论

Answer 2

重写onRestoreInstanceState(Bundle savedInstanceState)以在那里恢复日期。

另外，在你的onSaveInstanceState方法中调用'super.onSaveInstanceState`作为最后一条语句。