如何從類內的其他函數正確訪問方法？

Question

我從來沒有做過太多的Java編程，主要是所有的PHP/RUBY/Javascript，所以我不完全確定如何可能去訪問wLock.release()從onDestroy？

public class SlammedNavigatorActivity extends DroidGap { 
    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     super.loadUrl("file:///android_asset/www/index.html"); 

     PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE); 
     PowerManager.WakeLock wLock = pm.newWakeLock(PowerManager.SCREEN_DIM_WAKE_LOCK, "SN Wake Lock"); 
     wLock.acquire(); 
    } 

    public void onDestroy() { 
     wLock.release(); 
    } 
} 

Answer 1

你應該局部變量wLock轉換爲私有字段：

public class SlammedNavigatorActivity extends DroidGap { 
    private PowerManager.WakeLock wLock; 


    public void onCreate(Bundle savedInstanceState) { 
    // ... 
    wLock = pm.newWakeLock(PowerManager.SCREEN_DIM_WAKE_LOCK, "SN Wake Lock"); 
    // ... 
    } 
} 

Answer 2

使它成爲一個實例變量：

public class SlammedNavigatorActivity extends DroidGap { 

    private PowerManager.WakeLock wLock; 

    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     super.loadUrl("file:///android_asset/www/index.html"); 

     PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE); 
     this.wLock = pm.newWakeLock(PowerManager.SCREEN_DIM_WAKE_LOCK, "SN Wake Lock"); 
     wLock.acquire(); 

    } 

    public void onDestroy() { 
     this.wLock.release(); 
    } 
} 

你爲什麼不學習語言基礎知識做之前Android編程？閱讀Java tutorial，或者一本關於Java的好書。

Answer 3

製作wLock類成員

public class SlammedNavigatorActivity extends DroidGap { 

    private PowerManager.WakeLock wLock; 
    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     super.loadUrl("file:///android_asset/www/index.html"); 

     PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE); 
     wLock = pm.newWakeLock(PowerManager.SCREEN_DIM_WAKE_LOCK, "SN Wake Lock"); 
     wLock.acquire(); 

    } 

    public void onDestroy() { 

     wLock.release(); 
    } 
}