CODEWITHSUNDEEP
javaswinglayout-managerboxlayout
Kenlucius
Kenlucius

Reputation: 141

Aligning buttons to center in BoxLayout

I am trying to set the buttons to the center using the Box.createHorizontalStrut() method. However if I use this.getWidth()/2 is does not work. How can I do to center it in the frame.

Code

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);
    }
    
  
}

I have tried, this.getWidth()/2, p2.getWidth()/2, etc. However they don't work and the buttons are still starting from the beginning of the left side.

Upvotes: 1

Views: 2827

Answers (1)

MadProgrammer
MadProgrammer

Reputation: 347184

You could use a combination of Borderlayout, FlowLayout or GridBagLayout

For summary:

setLayout(new BorderLayout());
//...
p2.setLayout(new FlowLayout());
add(p1, BorderLayout.NORTH);
add(m);
//...
add(p2, BorderLayout.SOUTH);

The reason I might consider using BorderLayout of GridLayout for the core layout is it will give all the remaining space to the component in the CENTER position. This might not be what you want, but it's why I've used it.

Both GridBagLayout and FlowLayout will layout it's containers around the centre of the container, GridBagLayout doing it vertically and horizontally, FlowLayout doing it only horizontally (by default)

Buttons

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);
    }

}

But If I want to use BoxLayout for practice for p2. What should I put for the arguments in order to center the buttons???

Because the container's size dynamic, you could use some horizontal glue instead

    p2.add(Box.createHorizontalGlue());
    p2.add(left);
    p2.add(right);
    p2.add(Box.createHorizontalGlue());

Upvotes: 2

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