关于重写View的onDraw的问题

关于重写View的onDraw的问题：
首先里面的坐标参考点是屏幕左上角。
如果几个重写onDraw的View一起用，只有一个View能显示出来。第一个能显示。后面的显示不回来。Why？Iampuzzled.
importandroid.content.Context;
importandroid.content.res.TypedArray;
importandroid.graphics.Canvas;
importandroid.graphics.Color;
importandroid.graphics.Paint;
importandroid.graphics.Rect;
importandroid.graphics.Paint.Style;
importandroid.util.AttributeSet;
importandroid.util.Log;
importandroid.view.View;

publicclassMyViewextendsView{
privatePaintmPaint;
privateContextmContext;
privatestaticfinalStringmString="WelcometoMrWei'sblog";
finalstaticStringTAG="hubin";
intx=0;
inty=0;
intw=10;
inth=300;
voidsetX(intx)
{
this.x=x;
}
voidsetY(intx)
{
this.y=y;
}
booleanflag=false;
publicMyView(Contextcontext){
super(context);
mPaint=newPaint();
flag=true;
Log.i(TAG,"create1");
}

publicMyView(Contextcontext,AttributeSetattrs)//【如果在布局文件中定义了属性，就回调用该构造函数】
{
super(context,attrs);
mPaint=newPaint();
Log.i(TAG,"create3");
TypedArraya=context
.obtainStyledAttributes(attrs,R.styleable.MyView);

inttextColor=a.getColor(R.styleable.MyView_textColor,0XFFFFFFFF);
floattextSize=a.getDimension(R.styleable.MyView_textSize,36);

mPaint.setTextSize(textSize);
mPaint.setColor(textColor);

a.recycle();
}

@Override
protectedvoidonDraw(Canvascanvas){
Log.i(TAG,"flag:"+x);
//TODOAuto-generatedmethodstub
//super.onDraw(canvas);
//设置填充
mPaint.setStyle(Style.FILL);

//画一个矩形,前俩个是矩形左上角坐标，后面俩个是右下角坐标
canvas.drawRect(newRect(x,y,x+w,y+h),mPaint);

mPaint.setColor(Color.BLUE);
//绘制文字
canvas.drawText(mString,x+w,y+h,mPaint);


}
}