super.onDestroy(); 应该放在第一行还是放在最后一行？为什么？

放在第一行：

@Override
    public void onDestroy() {
        // TODO:  some code
        super.onDestroy();
    }

放在最后一行：

@Override
    public void onDestroy() {
        super.onDestroy();
        // TODO:  some code
    }

onDestroy到底做了那些事情？
看源码:

 protected void onDestroy() { 

    if (DEBUG_LIFECYCLE)  Slog.v(TAG, "onDestroy " + this); 

     mCalled = true; 

    // dismiss any dialogs we are managing.

    if (mManagedDialogs != null) { 

        final int numDialogs = mManagedDialogs.size(); 

        for (int i = 0; i < numDialogs; i++) {

        final ManagedDialog md = mManagedDialogs.valueAt(i); 

        if (md.mDialog.isShowing()) {

            md.mDialog.dismiss(); 

        } 

     } 

       mManagedDialogs = null;

     } 

     // close any cursors we are managing. 

      synchronized (mManagedCursors) {

     int numCursors = mManagedCursors.size(); 

     for (int i = 0; i < numCursors; i++) {

     ManagedCursor c = mManagedCursors.get(i);

     if (c != null) {

       c.mCursor.close();

      } 

     } 

     mManagedCursors.clear(); 

      }

     // Close any open search dialog 

     if (mSearchManager != null) { 

         mSearchManager.stopSearch();

      } 

     if (mActionBar != null) {

         mActionBar.onDestroy(); 

      } 

     getApplication().dispatchActivityDestroyed(this);

      }

继续往下走：android.app.Application#dispatchActivityDestroyed

   /* package */

void dispatchActivityDestroyed(Activity activity) {

Object[] callbacks = collectActivityLifecycleCallbacks();

if (callbacks != null) {

for (int i=0; i<callbacks.length; i++) {

((ActivityLifecycleCallbacks)callbacks[i]).onActivityDestroyed(activity);

}

}

}

继续往下走：

//activity 将从栈中移除

public void onActivityDestroyed(Activity activity) {

LogUtil.d("GIO.AppState", new Object[]{"onActivityDestroyed ", activity});

this.a().remove(activity);

this.t.remove(activity);

this.u.remove(activity);

}

所以在super()后再写操作可能会导致操作对象爆出NullPointerException；（只有一行代码之隔 概率还是很低的，但理论上是存在的）