本文介绍了JPanel上的组件未显示的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我创建了一个JPanel并对其进行了一些修改.我将背景更改为渐变颜色,这是该类.
I created a JPanel and i modify it a bit. I change it's background to gradient color here is the class.
public class JGradientPanel extends JPanel {
private static final int N = 32;
private Color color1, color2;
public JGradientPanel(Color color1, Color color2) {
this.setBorder(BorderFactory.createEmptyBorder(N, N, N, N));
this.color1 = color1;
this.color2 = color2;
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
//Color color1 = getBackground();
//Color color2 = color1.darker();
int w = getWidth();
int h = getHeight();
GradientPaint gp = new GradientPaint(
0, 0, color1, 0, h, color2);
g2d.setPaint(gp);
g2d.fillRect(0, 0, w, h);
}
}
现在我在面板上添加了一些组件,但是它什么也没显示,这是代码
Now i added few components to the panel but it didn't display anything, here is the code
public JPanel getMenu() {
JGradientPanel menu = new JGradientPanel(Color.WHITE, Color.white.darker());
int menuHeight = (int) ((int) getHeight() * 0.07);
menu.setPreferredSize(new Dimension(screenWidth,menuHeight));
menu.setLayout(new GridLayout(1,10));
menu.setBackground(Color.LIGHT_GRAY);
//test
JGradientButton test = new JGradientButton("test",Color.GREEN, Color.BLUE);
menu.add(test);
JLabel space = new JLabel(); // first blank space on the menu
space.setBounds(0, 0, menu.getPreferredSize().width - 50, menu.getPreferredSize().height);
space.setBorder(BorderFactory.createMatteBorder(0, 0, 0, 1, Color.GREEN));
menu.add(space);
JLabel moreSpaces[] = new JLabel[6];
buttons = new JButton[buttonLabels.length];
for(int counter = 0; counter < moreSpaces.length + buttonLabels.length; counter ++ ) {
if(counter < 3) {
buttons[counter] = new JButton(buttonLabels[counter]); //menu buttons
} else {
moreSpaces[counter - 3] = new JLabel(); // the rest of the blank in the menu
}
}
// adding components to menu panel
for(int counter = 0; counter < moreSpaces.length + buttonLabels.length; counter ++){
if(counter < 3) {
buttons[counter].setFocusPainted(false);
menu.add(buttons[counter]);
} else {
menu.add(moreSpaces[counter - 3]);
}
}
return menu;
}
我错过了什么还是做错了吗?我的代码有什么问题?
Did i miss something or i did it wrong? What's wrong with my code?
推荐答案
-
覆盖
public class JGradientPanel extends JPanel {
Swing绘画作者:
public void paintComponent(Graphics g) {
作者:默认从不返回 JPanel的PreferredSize ,Painting in Swing by
public void paintComponent(Graphics g) {
by default never to returns PreferredSize to JPanel,JPanel
返回Dimension[0, 0];
编辑
- 参见非常有用的内容,并且有关GradientPaint的有趣话题
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