[英]Drawing in multiple JPanels contained in one JPanel
I have a class which extends JPanel which contain 3 other panels. 我有一个扩展JPanel的类,其中包含3个其他面板。 I want to draw into the 3 panels. 我想画三个面板。 Here's what my code must be like, what am i doing wrong ? 这是我的代码必须是什么样的,我做错了什么? I just have an empty frame after execution. 执行后我只有一个空白框。
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Thumbnail extends JPanel {
private JPanel bigPanel;
private JPanel panelOne;
private JPanel panelTwo;
private JPanel panelThree;
public Thumbnail() {
panelOne = new JPanel() {
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(Color.black);
g.drawString("writing something", 10, 10);
g.drawRect(10, 10, 50, 50);
}
};
bigPanel = new JPanel();
bigPanel.add(panelOne);
this.setLayout(new FlowLayout(FlowLayout.LEFT));
this.add(bigPanel);
//other codes...
}
public static void main(String[] args) {
JFrame jf = new JFrame();
Thumbnail tb = new Thumbnail();
jf.add(tb);
jf.pack();
jf.setVisible(true);
}
}
bigPanel = new JPanel(new GridLayout(3,1));
bigPanel.add(panelOne, BorderLayout.NORTH);
bigPanel.add(panelTwo, BorderLayout.CENTER);
bigPanel.add(panelThree, BorderLayout.SOUTH);
. 。 . 。
this.getContentPane().add(bigPanel);
EDIT: 编辑:
It's better to extend a JDialog, and then to add JFrame and then all of your panel, only in case that the purpose is to use JDialog as your container, otherwise, your code is fine. 最好先扩展JDialog,然后再添加JFrame,然后再添加所有面板,仅在目的是将JDialog用作容器的情况下,否则代码就可以了。
panelOne
is not providing any layout information to the layout manager, which means, by default, it's preferred size is 0x0
panelOne
不向布局管理器提供任何布局信息,这意味着,默认情况下,其首选大小为0x0
Try adding something like... 尝试添加类似...
@Override
public Dimension getPreferredSize() {
return new Dimension(100, 100);
}
to panelOne
... 到panelOne
...
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.FlowLayout;
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Thumbnail extends JPanel {
private JPanel bigPanel;
private JPanel panelOne;
private JPanel panelTwo;
private JPanel panelThree;
public Thumbnail() {
panelOne = new JPanel() {
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(Color.black);
g.drawString("writing something", 10, 10);
g.drawRect(10, 10, 50, 50);
}
@Override
public Dimension getPreferredSize() {
return new Dimension(100, 100);
}
};
bigPanel = new JPanel();
bigPanel.add(panelOne);
this.setLayout(new FlowLayout(FlowLayout.LEFT));
this.add(bigPanel);
//other codes...
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame jf = new JFrame();
jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Thumbnail tb = new Thumbnail();
jf.add(tb);
jf.pack();
jf.setLocationRelativeTo(null);
jf.setVisible(true);
}
});
}
}
You might like to take a look at Initial Threads and Laying Out Components Within a Container for more details 您可能想看一下初始线程和在容器中布置组件以了解更多详细信息
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