栈处理问题

FLAG_ACTIVITY_CLEAR_TOP

只能处理一个activity存在的情况，如果我有多个activity  1234，如果这四个都存在我想从4到1 上面的方法可行

可是如果我开始是234然后从4到1 如何？

<activity android:name=".activities.A" 
          android:label="@string/A_title" 
          android:launchMode="singleTask"/> 
 
 
<activity android:name=".activities.B" 
          android:label="@string/B_title" 
          android:launchMode="singleTask"/> public class DontHackAndroidLikeThis extends Application { 
 
  private Stack<Activity> classes = new Stack<Activity>(); 
 
  public Activity getBackActivity() { 
    return classes.pop(); 
  } 
 
  public void addBackActivity(Activity activity) { 
    classes.push(activity); 
  }

From A to B:

DontHackAndroidLikeThis app = (DontHackAndroidLikeThis) getApplication(); 
app.addBackActivity(A.class);  
startActivity(this, B.class);

From B to C:

DontHackAndroidLikeThis app = (DontHackAndroidLikeThis) getApplication(); 
app.addBackActivity(B.class);  
startActivity(this, C.class);

In C:

If ( shouldNotGoBackToB() ) { 
  DontHackAndroidLikeThis app = (DontHackAndroidLikeThis) getApplication(); 
  app.pop(); 
}