我正在尝试使用该Box.createHorizontalStrut()
方法将按钮设置到中心。但是,如果我使用的this.getWidth()/2
是行不通的。如何将其在框架中居中。
package ch17;
import java.awt.Color;
import java.awt.Container;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
import javax.swing.border.TitledBorder;
public class Q17_1 extends JFrame{
JButton left = new JButton("<=");
JButton right = new JButton("=>");
JPanel p1 = new JPanel();
JRadioButton rb1 = new JRadioButton("Red");
JRadioButton rb2 = new JRadioButton("Yellow");
JRadioButton rb3 = new JRadioButton("White");
JRadioButton rb4 = new JRadioButton("Gray");
JRadioButton rb5 = new JRadioButton("Green");
JPanel p2 = new JPanel();
Message m = new Message("Welcome to Java");
public Q17_1(){
setLayout(new GridLayout(3,1));
p1.setBorder(new TitledBorder("Select Message Panel Background"));
ButtonGroup group = new ButtonGroup();
group.add(rb1);group.add(rb2);group.add(rb3);group.add(rb4);group.add(rb5);
rb1.setMnemonic('R');rb2.setMnemonic('Y');rb3.setMnemonic('W');rb4.setMnemonic('G');
rb5.setMnemonic('N');
p1.setLayout(new GridLayout(1,5,5,5));
p1.add(rb1);p1.add(rb2);p1.add(rb3);p1.add(rb4);p1.add(rb5);
p2.setLayout(new BoxLayout(p2,BoxLayout.X_AXIS));
add(p1);
add(m);
p2.add(Box.createHorizontalStrut(250));
p2.add(left);
p2.add(Box.createHorizontalStrut(5));
p2.add(right);
add(p2);
left.addActionListener((ActionEvent) -> {
m.moveLeft();
repaint();
});
right.addActionListener((ActionEvent)-> {
m.moveRight();
repaint();
});
rb1.addActionListener(m);
rb2.addActionListener(m);
rb3.addActionListener(m);
rb4.addActionListener(m);
rb5.addActionListener(m);
}
public static void main(String[] args) {
Q17_1 frame = new Q17_1();
frame.pack();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}
我已经试过了,this.getWidth()/2
,p2.getWidth()/2
等,但他们没有工作和按钮仍然处于从左侧的起点开始。
你可以使用的组合Borderlayout
,FlowLayout
或GridBagLayout
总结:
setLayout(new BorderLayout());
//...
p2.setLayout(new FlowLayout());
add(p1, BorderLayout.NORTH);
add(m);
//...
add(p2, BorderLayout.SOUTH);
我可能会考虑使用的原因BorderLayout
中GridLayout
的核心布局是它会给所有剩余空间的组件CENTER
位置。这可能不是您想要的,但这就是我使用它的原因。
双方GridBagLayout
并FlowLayout
会布置它的容器围绕容器的中心,GridBagLayout
做垂直和水平方向,FlowLayout
这样做只会水平(默认)
import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import javax.swing.Box;
import javax.swing.ButtonGroup;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.border.TitledBorder;
public class Q17_1 extends JFrame {
JButton left = new JButton("<=");
JButton right = new JButton("=>");
JPanel p1 = new JPanel();
JRadioButton rb1 = new JRadioButton("Red");
JRadioButton rb2 = new JRadioButton("Yellow");
JRadioButton rb3 = new JRadioButton("White");
JRadioButton rb4 = new JRadioButton("Gray");
JRadioButton rb5 = new JRadioButton("Green");
JPanel p2 = new JPanel();
JLabel m = new JLabel("Welcome to Java");
// Message m = new Message("Welcome to Java");
public Q17_1() {
setLayout(new BorderLayout());
p1.setBorder(new TitledBorder("Select Message Panel Background"));
ButtonGroup group = new ButtonGroup();
group.add(rb1);
group.add(rb2);
group.add(rb3);
group.add(rb4);
group.add(rb5);
rb1.setMnemonic('R');
rb2.setMnemonic('Y');
rb3.setMnemonic('W');
rb4.setMnemonic('G');
rb5.setMnemonic('N');
p1.setLayout(new GridLayout(1, 5, 5, 5));
p1.add(rb1);
p1.add(rb2);
p1.add(rb3);
p1.add(rb4);
p1.add(rb5);
p2.setLayout(new FlowLayout());
add(p1, BorderLayout.NORTH);
add(m);
p2.add(left);
p2.add(right);
add(p2, BorderLayout.SOUTH);
left.addActionListener((ActionEvent) -> {
// m.moveLeft();
// repaint();
});
right.addActionListener((ActionEvent) -> {
// m.moveRight();
// repaint();
});
// rb1.addActionListener(m);
// rb2.addActionListener(m);
// rb3.addActionListener(m);
// rb4.addActionListener(m);
// rb5.addActionListener(m);
}
public static void main(String[] args) {
Q17_1 frame = new Q17_1();
frame.pack();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}
但是,如果我想使用BoxLayout进行p2练习。为了使按钮居中,我应该为参数添加什么???
由于容器的尺寸是动态的,因此您可以使用一些水平胶水来代替
p2.add(Box.createHorizontalGlue());
p2.add(left);
p2.add(right);
p2.add(Box.createHorizontalGlue());
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