Setting size of a JPanel in GroupLayout

Question

I have a JFrame and i have the set the layout to GroupLayout.

i am adding two Jpanel i.e workingPanel(red) , backgroundPanel(green) .

I want the green colored panel to be of less height say 50 or 60.i have set the size of backgroundPanel to 50 but on addding it to the Jframe the height of the backgroundPanel is same as workingPanel.

and the code is `import javax.swing.; import java.awt.;

public class Home extends JFrame{

JButton b1;
JPanel workingPanel,backgroundPanel;

public Home(){

    new JFrame("Restaurant Billing");
    b1=new JButton("Hello");
    workingPanel=new JPanel(); 
    backgroundPanel=new JPanel();
    int maximumWidth=getContentPane().getWidth();
    backgroundPanel.setSize(maximumWidth,60);
    workingPanel.setBackground(Color.red); //workingpanel backgroundcolor is red
    backgroundPanel.setBackground(Color.green);//backgroundPanle backcolor is green
    //creating grouplayout and setting to mainframe
    GroupLayout layout=new GroupLayout(getContentPane());
    getContentPane().setLayout(layout);

    layout.setHorizontalGroup(
        layout.createParallelGroup()
        .addComponent(backgroundPanel)
        .addComponent(workingPanel)
    );
      layout.setVerticalGroup(
        layout.createSequentialGroup()
        .addComponent(backgroundPanel)
        .addComponent(workingPanel)

      );


    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

}
public void launchFrame(){

    this.setVisible(true);
}
}

Plz help me.

Answer 1

Try to use the prefferedSize properties.

backgroundPanel.setPrefferedSize(maximumWidth,60);

Answer 2

Try using the 'setMaximumSize()' method. This will keep the component height from extending beyond the desired range. And if one prefers to maintain the component width equal to that of the frame, then 'getMaximumSize().width' can be used to specify the component width. This will allow the component to resize to full-frame width in case the frame is manually resized.

backgroundPanel.setMaximumSize(new Dimension(backgroundPanel.getMaximumSize().width, 60));

The full code:

import javax.swing.*;
import java.awt.*;
public class Home extends JFrame{
    JButton b1;
    JPanel workingPanel,backgroundPanel;
    public Home(){

        new JFrame("Restaurant Billing");
        setPreferredSize(new Dimension(500,500));
        setSize(new Dimension(500,500));
        b1=new JButton("Hello");
        workingPanel=new JPanel(); 
        backgroundPanel=new JPanel();
        int maximumWidth = backgroundPanel.getMaximumSize().width;
        backgroundPanel.setMaximumSize(new Dimension(maximumWidth, 60));
        workingPanel.setBackground(Color.red); //workingpanel backgroundcolor is red
        backgroundPanel.setBackground(Color.green);//backgroundPanle backcolor is green
        //creating grouplayout and setting to mainframe
        GroupLayout layout=new GroupLayout(getContentPane());
        getContentPane().setLayout(layout);

        layout.setHorizontalGroup(
            layout.createParallelGroup()
            .addComponent(backgroundPanel)
            .addComponent(workingPanel)
        );
          layout.setVerticalGroup(
            layout.createSequentialGroup()
            .addComponent(backgroundPanel)
            .addComponent(workingPanel)

          );


        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    }
    public void launchFrame(){

        this.setVisible(true);
    }
    public static void main(String args[]) {
        Home home = new Home();
        home.launchFrame();
    }
}

Answer 3

To adjust the size, I looked at the class properties, I couldn't find anything, something to trigger. The best solution is like this.

package groupleyaut;

import java.awt.EventQueue;
import javax.swing.JFrame;
import  javax.swing.JPanel;
import java.awt.BorderLayout;
import javax.swing.GroupLayout;
import javax.swing.GroupLayout.Alignment;
import java.awt.Color;
import java.awt.Dimension;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;

public class gfg {
`enter code here`private JFrame frame;

/**
 * Launch the application.
 */
public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                gfg window = new gfg();
                window.frame.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}

/**
 * Create the application.
 */
public gfg() {
    initialize();
}

/**
 * Initialize the contents of the frame.
 */
private void initialize() {
    frame = new JFrame();
    frame.setBounds(100, 100, 807, 325);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    JPanel panel = new JPanel();
    panel.setBackground(Color.BLACK);
    frame.getContentPane().add(panel, BorderLayout.CENTER);

    JPanel panel_1 = new JPanel();
    panel_1.setPreferredSize(new Dimension(10, 100));

    JPanel panel_2 = new JPanel();
    panel_2.setPreferredSize(new Dimension(200, 50));
    GroupLayout gl_panel = new GroupLayout(panel);
    gl_panel.setHorizontalGroup(
        gl_panel.createParallelGroup(Alignment.LEADING)
            .addGroup(gl_panel.createSequentialGroup()
                .addContainerGap()
                .addComponent(panel_1, GroupLayout.PREFERRED_SIZE, panel_1.getPreferredSize().width, GroupLayout.PREFERRED_SIZE)
                .addGap(64)
                .addComponent(panel_2, GroupLayout.PREFERRED_SIZE, 492, GroupLayout.PREFERRED_SIZE)
                .addContainerGap(166, Short.MAX_VALUE))
    );
    gl_panel.setVerticalGroup(
        gl_panel.createParallelGroup(Alignment.LEADING)
            .addGroup(gl_panel.createSequentialGroup()
                .addContainerGap()
                .addGroup(gl_panel.createParallelGroup(Alignment.LEADING)
                    .addComponent(panel_2, GroupLayout.PREFERRED_SIZE, 128, GroupLayout.PREFERRED_SIZE)
                    .addComponent(panel_1, GroupLayout.PREFERRED_SIZE, panel_1.getPreferredSize().height, GroupLayout.PREFERRED_SIZE))
                .addGap(66))
    );
    panel_2.setLayout(null);

    JButton btnNewButton = new JButton("New button");
    btnNewButton.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            panel_1.setPreferredSize(new Dimension(10, 200));
            GroupLayout gl_panel = new GroupLayout(panel);
            gl_panel.setHorizontalGroup(
                gl_panel.createParallelGroup(Alignment.LEADING)
                    .addGroup(gl_panel.createSequentialGroup()
                        .addContainerGap()
                        .addComponent(panel_1, GroupLayout.PREFERRED_SIZE, panel_1.getPreferredSize().width, GroupLayout.PREFERRED_SIZE)
                        .addGap(64)
                        .addComponent(panel_2, GroupLayout.PREFERRED_SIZE, 492, GroupLayout.PREFERRED_SIZE)
                        .addContainerGap(166, Short.MAX_VALUE))
            );
            gl_panel.setVerticalGroup(
                gl_panel.createParallelGroup(Alignment.LEADING)
                    .addGroup(gl_panel.createSequentialGroup()
                        .addContainerGap()
                        .addGroup(gl_panel.createParallelGroup(Alignment.LEADING)
                            .addComponent(panel_2, GroupLayout.PREFERRED_SIZE, 128, GroupLayout.PREFERRED_SIZE)
                            .addComponent(panel_1, GroupLayout.PREFERRED_SIZE, panel_1.getPreferredSize().height, GroupLayout.PREFERRED_SIZE))
                        .addGap(66))
            );
            panel.setLayout(gl_panel);

        }
    });
    btnNewButton.setBounds(147, 42, 89, 23);
    panel_2.add(btnNewButton);
    panel.setLayout(gl_panel);


}

}