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我嘗試製作一個JFrame,其中包含一個JPanel(其中包含一個圓圈),並且它由四個按鈕(北,南,東,西)界定。圓圈將按照按下的按鈕指示的方向移動。
我的問題是,我不能設法把我的JPanel的中心:如何將JPanel添加到JFrame的中心?
Jframe的階級是這樣的:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
@SuppressWarnings("serial")
public class Frame extends JFrame implements ActionListener {
JButton north, south, east, west;
int x = 10, y = 10;
MyPanel panel;
public Frame() {
setLayout(new BorderLayout());
panel = new MyPanel();
panel.setBackground(Color.MAGENTA);
north = new JButton("NORTH");
south = new JButton("SOUTH");
east = new JButton("EAST");
west = new JButton("WEST");
add(panel, BorderLayout.CENTER);
add(north, BorderLayout.NORTH);
add(south, BorderLayout.SOUTH);
add(east, BorderLayout.EAST);
add(west, BorderLayout.WEST);
north.addActionListener(this);
south.addActionListener(this);
east.addActionListener(this);
west.addActionListener(this);
setBounds(100, 100, 300, 300);
setVisible(true);
}
@Override
public void actionPerformed(ActionEvent e) {
if (e.getSource() == north) {
y -= 3;
panel.setY(y);
panel.repaint();
}
if (e.getSource() == south) {
y += 3;
panel.setY(y);
panel.repaint();
}
if (e.getSource() == east) {
x += 3;
panel.setX(x);
panel.repaint();
}
if (e.getSource() == west) {
x -= 3;
panel.setX(x);
panel.repaint();
}
}
}
而且MyPanel類看起來是這樣的:
import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JPanel;
@SuppressWarnings("serial")
public class MyPanel extends JPanel {
private Color color = Color.CYAN;
private int x = 10, y = 10;
public void paint(Graphics g) {
super.paintComponent(g);
g.setColor(color);
g.fillOval(x, y, 20, 20);
}
public int getX() {
return x;
}
public void setX(int x) {
this.x = x;
}
public int getY() {
return y;
}
public void setY(int y) {
this.y = y;
}
}
[many duplicates](https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=site:stackoverflow.com+java+swing+center+jpanel+ in + jframe) –
@HovercraftFullOfEels,請查看圖片和代碼(在將問題保留爲重複之前)。當使用簡單的BorderLayout時,爲什麼洋紅色面板會被塗在其他組件上?洋紅色的面板應該在中間。問題是我們看不到的代碼.. – camickr
此問題最初是作爲以下副本而封閉的:http://stackoverflow.com/questions/7223530/how-can-i-properly-center-a-jpanel-fixed -size-內-A-的JFrame。我重新開放它,因爲我不相信它是重複的。如果將「MyPanel」替換爲「JPanel」,面板將顯示在中心。所以問題出在自定義的「MyPanel」類中,我們無法訪問該代碼,因此我們無法提供幫助。 – camickr