Question

为什么我在JAVA中覆盖paintcomponent方法时说不能覆盖或实现超类方法

@SuppressWarnings("serial")
class SingleWaveformPanel extends Panel
{
public AudioInfo a = null;

SingleWaveformPanel(AudioInfo a)
{
this.a = a;
}
@Override
protected void paintComponent(Graphics g)
{
int oldx = 0;
int oldy = (int) (getHeight()/2);
int xIndex = 0;
g.setColor(Color.WHITE);
g.fillRect(0, 0, getWidth(),getHeight());
int t = 0;
int increment = a.buf.length/getWidth();
g.setColor(Color.RED);
for(t = 0; t<a.buf.length;t+=1)
{
double scaleFactor = a.toReturn[0][t]/getHeight();
double scalesample = a.buf[t] * scaleFactor;

int y = (int)((getHeight()/2)-(scalesample));

g.drawLine(oldx,oldy,xIndex,y);

xIndex++;
oldx = xIndex;
oldy = y;
}
}
}

Answer 1

添加一个构造方法。。继承panel就好了
如：
public SingleWaveformPanel()
{
super();
}