我正在学习Swing,并为自己练习构建了一个示例GUI。非常基础,它在JFrame
的西、中、东三个面板上有三个面板。在最后一个面板中,有另一个面板和一个按钮。该面板是我的扩展JPanel
,名为DrawPanel
。每次单击其下方的Repaint按钮时,它会绘制一个随机的Rectangle
。这是我的代码:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Tester
{
public static DrawPanel panelEastDrawPanelCenter;
public static void main()
{
Tester gui = new Tester();
gui.go();
}
public void go()
{
JFrame frame = new JFrame("This is the title");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Create all the Western Panel components
JPanel panelWest = new JPanel();
// panelWest.setLayout(new BorderLayout());
JButton panelWestButtonWest = new JButton("Western-most West Button");
JButton panelWestButtonCenter = new JButton("Western-most Center Button");
JButton panelWestButtonEast = new JButton("Western-most East Button");
// Create all Center Panel components
JPanel panelCenter = new JPanel();
panelCenter.setBackground(Color.darkGray);
JButton panelCenterButtonCenter = new JButton("Center Button");
// Create all East Panel components
JPanel panelEast = new JPanel();
panelEastDrawPanelCenter = new DrawPanel();
panelEastDrawPanelCenter.setSize(50,50);
JButton panelEastButtonSouth = new JButton("Repaint");
panelEastButtonSouth.addActionListener(new panelEastButtonSouthListener());
// Add everything to the GUI
// West Panel
frame.getContentPane().add(BorderLayout.WEST, panelWest);
panelWest.add(BorderLayout.WEST, panelWestButtonWest);
panelWest.add(BorderLayout.CENTER, panelWestButtonCenter);
panelWest.add(BorderLayout.EAST, panelWestButtonEast);
// Center Panel
frame.getContentPane().add(BorderLayout.CENTER, panelCenter);
panelCenter.add(BorderLayout.CENTER, panelCenterButtonCenter);
// East Panel
frame.getContentPane().add(BorderLayout.EAST, panelEast);
panelEast.add(panelEastDrawPanelCenter);
panelEast.add(panelEastButtonSouth);
frame.pack();
//frame.setSize(frame.getWidth(), 500);
frame.setVisible(true);
}
class panelEastButtonSouthListener implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
panelEastDrawPanelCenter.repaint();
}
}
class DrawPanel extends JPanel // JPanel that displays a rectangle upon clicking the button "Repaint"
{
public void paintComponent(Graphics g)
{
g.setColor(Color.WHITE); // Removes previous rectangle
g.fillRect(0,0, this.getWidth(),this.getHeight());
g.setColor(randColor()); // Puts a new rectangle on screen, rand size and color
int height = (int)(Math.random() * this.getHeight());
int width = (int)(Math.random() * this.getHeight());
int x = (int)(Math.random() * 20);
int y = (int)(Math.random() * 20);
g.fillRect(x,y, height,width);
}
public Color randColor()
{
int r = (int)(Math.random() * 255);
int g = (int)(Math.random() * 255);
int b = (int)(Math.random() * 255);
return new Color(r, g, b);
}
}
}
我遇到的问题是虽然我明确地为
DrawPanel
对象(panelEastDrawPanelCenter
)设置了50×50的大小,但当我运行程序时,它(DrawPanel
)仍然是一个小面板,紧挨着按钮,而panelEast(包含DrawPanel
和按钮的容器)仍然是相同的宽度(永远不会变宽)。我意识到我可以这样说frame.pack();
frame.setSize(frame.getWidth(), 500);
如果我将东侧面板设置为使用 BorderLayout
或 BoxLayout
布局,这将使 DrawPanel
显示更大。
- 但我不明白为什么设置
DrawPanel
对象的大小实际上并没有改变其大小,而且无论我执行setSize(50,50);
,它都保持很小。 - 我该如何让中间面板停止调整大小,以便东侧面板可以调整为更宽?或者如何调整东侧面板的大小?
setPreferredSize(Dimension d)
而不是重写getPreferredSize()
呢?:-. - ZéychinComponent
下查找了),当我尝试在我的代码中使用它时,它显示“no suitable method found for setPreferredSize(int,int)
”。 - Alex GsetPreferredSize(Dimension d)
,忽略我之前的评论... - Alex G