意外的應用程序關閉

Question

我試圖啓動此代碼，以便打印行onTouch。該代碼不包含錯誤，但是當我啓動它時...模擬器意外關閉。你能幫我弄清楚這個問題嗎？

import android.app.Activity; 
import android.graphics.Bitmap; 
import android.graphics.Canvas; 
import android.graphics.Color; 
import android.graphics.Paint; 
import android.os.Bundle; 
import android.view.Display; 
import android.view.MotionEvent; 
import android.view.View; 
import android.view.View.OnTouchListener; 
import android.widget.ImageView; 

public class Usama3 extends Activity { 

     ImageView imageView; 
     Bitmap bitmap; 
     Canvas canvas; 
     Paint paint; 

     @Override 
     public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.main); 

     imageView = (ImageView) this.findViewById(R.id.imageView11); 

     Display currentDisplay = getWindowManager().getDefaultDisplay(); 
     float dw = currentDisplay.getWidth(); 
     float dh = currentDisplay.getHeight(); 
     bitmap = Bitmap.createBitmap((int)dw,(int)dh,Bitmap.Config.ARGB_8888); 
     canvas = new Canvas(bitmap); 
     paint = new Paint(); 
     paint.setColor(Color.GREEN); 
     imageView.setImageBitmap(bitmap); 
     imageView.setOnTouchListener((OnTouchListener) this); 

     } 
     public boolean onTouch(View v, MotionEvent event) { 

     int action = event.getAction(); 
     float upx; 
     float upy; 
     float downy = 0; 
     float downx = 0; 
     switch (action) 
     { 
      case MotionEvent.ACTION_MOVE: 
      upx = event.getX(); 
      upy = event.getY(); 
      canvas.drawLine(downx, downy, upx, upy, paint); 
      imageView.invalidate(); 
      downx = upx; 
      downy = upy; 
      break; 
     } 
     return false; 
} 

} 

我會真的很感謝

Answer 1

檢查Usama3是在你的AndroidManifest。您可能還需要讓該活動明確實施OnTouchListener，而不是嘗試將類別轉換爲this。 Android開發人員網站上有一個關於debugging的部分，您可能會發現有助於閱讀。