SavedInstanceState爲空

Question

我想在與其他設備「同步」時獲取當前系統時間。因此，此活動通常在同步後調用/顯示。

目前，當前系統時間是正確的，但我也有警報彈出另一個活動，一旦我完成了該活動，我想回到此活動。一旦我這樣做，系統時間會更新到最新的時間，而不是舊的當前時間（這正是我想要的）。

我試圖使用SavedInstanceState保存舊的當前時間的狀態，並且它確實在onSavedInstanceState中獲得正確的字符串。當我回到此活動時，SavedInstanceState爲空。我不知道爲什麼？

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; 

    } 

} 

} 

編輯：我試圖把這個：super.onSaveInstanceState(savedInstanceState);在方法的結束，但仍然無法正常工作。

Answer 1

您不應該將onSave中的相同代碼放入onRestore中。相反，將完整的if語句從onCreate方法複製到onRestore方法中。並以super.onRestoreInstanceState作爲第一條語句。

編輯：對不起 - 本意是發表評論

Answer 2

重寫onRestoreInstanceState(Bundle savedInstanceState)以在那裏恢復日期。

另外，在你的onSaveInstanceState方法中調用'super.onSaveInstanceState`作爲最後一條語句。