[英]JPanel with JSlider not displaing the Graphics
All i have is a JPanel with a white background and the JSlider on the bottom, not displaying the square, i think i have made some mistake with the JPanel class but i can't figure it out. 我所拥有的只是一个带有白色背景的JPanel,底部是JSlider,没有显示正方形,我想我对JPanel类犯了一些错误,但是我无法弄清楚。 Just before i made another project with g.fillOval and it worked properly, i checked it out and every line of code seems the same, i am really confused.
在我使用g.fillOval进行另一个项目并正常工作之前,我将其签出,每一行代码似乎都一样,我真的很困惑。
public class Main00 {
public static void main(String[] args) {
Gui asd=new Gui();
asd.setVisible(true);
asd.setSize(500,400);
}
}
import java.awt.*;
import javax.swing.*;
import javax.swing.event.*;
public class Gui extends JFrame {
private JSlider slider;
private DrawSquare square;
public Gui() {
super("square modificator");
setDefaultCloseOperation(EXIT_ON_CLOSE);
square = new DrawSquare();
square.setBackground(Color.WHITE);
slider = new JSlider(SwingConstants.HORIZONTAL, 0, 300,
square.getSide());
slider.setMajorTickSpacing(20);
slider.setPaintTicks(true);
add(square);
add(slider, BorderLayout.SOUTH);
slider.addChangeListener(new ChangeListener() {
@Override
public void stateChanged(ChangeEvent e) {
square.setSide(slider.getValue());
}
});
}
}
import java.awt.*;
import javax.swing.*;
public class DrawSquare extends JPanel {
private int side = 10;
public void paintComponents(Graphics g) {
super.paintComponents(g);
g.setColor(Color.RED);
g.fillRect(20, 20, side, side);
}
public void setSide(int side) {
this.side=(side>=0)?side:0;
repaint();
}
public Dimension getPrefferedSize(){
return new Dimension(200,200);
}
public Dimension getMinimumSize(){
return getPrefferedSize();
}
public int getSide(){
return side;
}
}
You're overriding paintComponents
rather than the correct paintComponent
. 您要覆盖
paintComponents
而不是正确的paintComponent
。 These two methods have drastically different effects, and the effect of the second is the one you want. 这两种方法的效果截然不同,第二种方法的效果是您想要的。
From the API: 从API:
Again, you are interested in painting the component itself via its delegate and not in painting the components held by this component. 同样,您有兴趣通过组件的代理绘制组件本身,而不是绘制由该组件持有的组件。
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