[英]Shape is not showing on paintComponent method using Swing
運行我的程序時,不會顯示為fillOval的形狀。 我擴展了JPanel,但似乎出現了問題,因為我看不到fillOval。 這是我的代碼:
public class MovingBall extends JPanel{
public MovingBall(){
}
public static void main(String[] args) {
JFrame frame = new JFrame();
JPanel panel = new JPanel();
frame.add(panel);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(500,700);
panel.setBackground(Color.BLACK);
frame.setVisible(true);
MovingBall movingBall = new MovingBall();
frame.add(movingBall);
}
@Override
public void paintComponent(Graphics canvas){
super.paintComponent(canvas);
canvas.setColor(Color.BLUE);
canvas.fillOval(50, 90, 20, 20);
}
}
將這些行frame.setSize(500,700);
之前frame.setSize(500,700);
呼叫
MovingBall movingBall = new MovingBall();
frame.add(movingBall);
或致電
frame.revaliedate();
frame.repaint();
添加后
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