android - 関数呼び出し時の Android Null 例外

Question

色の整数をパラメーターとして渡すことでボタンのクリック時に色を変更したいのですが、クリックするとAndroidがNull Pointer Exceptionのエラーをスローします。そしてアプリケーションがクラッシュします..私はここで立ち往生しています親切に助けてください関数名はSetColor()です

   MyView Class

  public class MyView extends Activity {

   Button brushLarge;
   Button brushMeduim;
   Button brushSmall;
   Button erase;
   Button save;
   Button trash;
   Button rainbow;
   Button color1;
    Button color2;
        Button color3;
     this.color1 = ((Button)findViewById(R.id.color1));
     this.color2 = ((Button)findViewById(R.id.color2));
     this.color3 = ((Button)findViewById(R.id.color3));
      this.color1.setOnClickListener(new View.OnClickListener()
      {
        public void onClick(View paramView)
        {
     Toast.makeText(getApplicationContext(), "color1", Toast.LENGTH_LONG).show();
          //MyView.this.coloringView.setColor("#CD5C5C");
        }
      });
      this.color2.setOnClickListener(new View.OnClickListener()
      {
        public void onClick(View paramView)
        {
            //DrawView.changePaintColor(0xFFFF0000);0);
            try
            {coloringView.changePaintColor(0xFFFF0000); 
            }
            catch(Exception e)
            {
  Toast.makeText(getApplicationContext(), "color1"+e,Toast.LENGTH_LONG).show();
            } 
            //coloringView.changePaintColor(0xFFFF0000);    
        }
      });
      this.color3.setOnClickListener(new View.OnClickListener()
      {
        public void onClick(View paramView)
        {
          MyView.this.coloringView.setColor("#FA8072");
        }
      });
      return;
    }
}

  DrawView Class    

    public class DrawView extends View {
    private Paint paint = new Paint();
    private Path path = new Path();
    private Paint circlePaint = new Paint();
    private Path circlePath = new Path();
    Canvas mCanvas;
    String color = "#ffee22";


      public DrawView(Context context, AttributeSet attrs) {
            super(context, attrs);

        paint.setAntiAlias(true);
        paint.setColor(Color.GREEN);
        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeJoin(Paint.Join.ROUND);
        paint.setStrokeWidth(15f);

        circlePaint.setAntiAlias(true);
        circlePaint.setColor(Color.BLUE);
        circlePaint.setStyle(Paint.Style.STROKE);
        circlePaint.setStrokeJoin(Paint.Join.MITER);
        circlePaint.setStrokeWidth(4f);
mCanvas=new Canvas();
    }
       public void changePaintColor(int color){
            this.paint.setColor(color);
        }

    @Override
    protected void onDraw(Canvas canvas) {

        canvas.drawPath(path, paint);
        canvas.drawPath(circlePath, circlePaint);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {

        // Gives you x and y coordinates on the Event.
        float pointX = event.getX();
        float pointY = event.getY();

        // Checks for the event that occurs
        switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
            path.moveTo(pointX, pointY);

            return true;
        case MotionEvent.ACTION_MOVE:
            path.lineTo(pointX, pointY);
            circlePath.reset();

            // (circle's center x-coordinate, y-coordinate, radius of the
            // circle, direction to wind the shape)
            circlePath.addCircle(pointX, pointY, 30, Path.Direction.CW);
            //circlePath.addRect(pointX - 25, pointY - 25, pointX + 25, pointY + 25, Path.Direction.CW);
/*          RectF rect = new RectF(pointX - 25, pointY - 25, pointX + 25, pointY + 25);
            circlePath.addRoundRect(rect, 0, 0, Path.Direction.CW);
*/
            break;

        case MotionEvent.ACTION_UP:
            circlePath.reset();

            break;
        default:
            return false;
        }

        // Schedules a repaint.
        // Force a view to draw.
        postInvalidate();
        return true;
    }
/////function------------------------------------
    public void apple()
    {
    //  paint.setColor(ap);
        //Toast.makeText(getContext(), "Rehman", Toast.LENGTH_SHORT).show();
        this.paint.setColor(0xFF0000FF);


    }


    public void setColor(String color)
    {


        this.paint.setColor(0xFF0000FF);    
    }
    public void onSizeChange(int paramInt)
      {
       paint.setStrokeWidth(paramInt);
      }
      public void clear()
      {
        if (this.mCanvas != null)
        {
          this.paint.setARGB(255, 255, 255, 255);
          mCanvas.drawPaint(this.paint);
          invalidate();
          paint.setColor(Color.parseColor(this.color));
        }
      }

}