捆綁丟失值

我是新來的java。我試圖在屏幕旋轉時將變量從OnSaveInstanceState保存到OnCreate。我已將登錄的值保存到savedInstanceState包中。當屏幕旋轉時，在日誌中顯示的OnCreate(Bundle savedInstanceState)中的Bundle值爲0，但在日誌中顯示爲OnSaveInstanceState的正確值。捆綁丟失值

我的動態Java是

package com.hfad.stopwatch; 

import android.app.Activity; 
import android.os.Bundle; 
import android.os.Handler; 
import android.util.Log; 
import android.view.View; 
import android.widget.TextView; 

public class StopwatchActivity extends Activity { 

    private static final String TAG = StopwatchActivity.class.getSimpleName(); 
    private int seconds; 
    private boolean running; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_stopwatch); 
     if(savedInstanceState != null){ 
      Log.d(TAG, "onCreate() Restoring previous state"); 
      /* restore state */ 
      seconds = savedInstanceState.getInt("seconds"); 
      running = savedInstanceState.getBoolean("running"); 
      String tmpStr = String.valueOf(seconds); 
      Log.d(TAG,tmpStr); 
      Log.d(TAG, "onCreate() ending"); 
     } else { 
      Log.d(TAG, "onCreate() No saved state available"); 
      /* initialize app */ 
     } 
     runTimer(); 
    } 

    @Override 
    public void onSaveInstanceState(Bundle savedInstanceState){ 
     super.onSaveInstanceState(savedInstanceState); 
     Log.d(TAG,"onSaveInstanceState() saving state"); 
     savedInstanceState.putInt("Seconds", seconds); 
     savedInstanceState.putBoolean("running", running); 
     String tmpStr = String.valueOf(savedInstanceState.getInt("Seconds")); 
     Log.d(TAG,tmpStr); 
     Log.d(TAG,"onSaveInstanceState() ending"); 
    } 

    //Start the stopwatch running when the start button is clicked 
    public void onClickStart(View view){ 
     running = true; 
    } 

    //Stop the stopwatch running when the stop button is clicked 
    public void onClickStop(View view){ 
     running = false; 
    } 

    //Start the stopwatch running when the start button is clicked 
    public void onClickReset(View view){ 
     running = false; 
     seconds = 0; 
    } 

    private void runTimer(){ 
     final TextView timeView = (TextView)findViewById(R.id.time_view); 
     final Handler handler = new Handler(); 
     handler.post(new Runnable(){ 
      @Override 
      public void run(){ 
       int hours = seconds/3600; 
       int minutes = (seconds%3600)/60; 
       int secs = seconds%60; 
       String time = String.format("%d:%02d:%02d",hours,minutes,secs); 
       timeView.setText(time); 
       if(running){ 
        seconds++; 
       } 
       handler.postDelayed(this, 1000); 
      } 
     }); 
    } 

}

這是日誌。

07-26 21:02:19.880 6124-6124/com.hfad.stopwatch D/StopwatchActivity: onSaveInstanceState() saving state 

07-26 21:02:19.880 6124-6124/com.hfad.stopwatch D/StopwatchActivity: 11 

07-26 21:02:19.880 6124-6124/com.hfad.stopwatch D/StopwatchActivity: onSaveInstanceState() ending 

07-26 21:02:19.940 6124-6124/com.hfad.stopwatch D/StopwatchActivity: onCreate() Restoring previous state 

07-26 21:02:19.940 6124-6124/com.hfad.stopwatch D/StopwatchActivity: 0 

07-26 21:02:19.940 6124-6124/com.hfad.stopwatch D/StopwatchActivity: onCreate() ending

我在一本書中學習下面的內容，但是這不起作用，並且我無法在線找到解決方案。

來源

2016-07-26 fatmanming

你應該標記爲接受，如果它幫助你的答案之一。請遵循SO的規則。 – Intern

設置好要保存的值後，應該調用super.onSaveInstanceState(savedInstanceState)。

你可以看到更多的in the documentations

來源

2016-07-26 20:08:25

您使用了錯誤的鍵查找值。鑰匙中有一個首都S。 Bundle中的密鑰區分大小寫。

這裏的一個好習慣是將密鑰字符串聲明爲最終靜態並使用它們來存儲和檢索。例如。

public static final String SECONDS_KEY = "seconds"; 
public static final String RUNNING_KEY = "running"

來源

2016-07-26 20:08:48 Nerd

謝謝，我會牢記這一點。 – fatmanming

捆綁包區分大小寫。您正在放入「秒」並檢索「秒」。好的做法是將鍵定義爲常量，這樣您就不會遇到這樣的錯誤。

Bundle - is key case sensitive?

來源

2016-07-26 20:09:40 headsvk

謝謝，下面的例子讓我對打字錯誤一無所知。 – fatmanming

回答

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