How to set the last button's height of a row in GridBagLayout component?

Question

I'm going to develop a Calculator program in Java, I used GridBagLayout, I want put a big "=" button at the bottom right, but that button's height won't expend to the last space as expected, my major code is pasted as below, please help to advise how to figure that: my problem one is like this

import java.awt.BorderLayout;
import java.awt.Button;
import java.awt.Color;
import java.awt.Frame;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.Panel;
import java.awt.TextField;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

import javax.swing.JButton;

import org.omg.CORBA.PUBLIC_MEMBER;

public class MyCalculater {
    private Frame frame = new Frame("My-Calculator");
    private GridBagConstraints gBagConstraints = new GridBagConstraints();
    private GridBagLayout gBagLayout = new GridBagLayout();
    private Panel screen = new Panel();
    private Panel arithSymbolArea = new Panel();
    private Panel digitalArea = new Panel();
    private JButton[] digitalButtons = new JButton[10];

    public void init() {
        // Put a screen for output
        screen.add(new TextField(40));
        frame.add(screen, BorderLayout.NORTH);

        // To put the Arith symbols
        arithSymbolArea.setLayout(new GridLayout(6, 4));
        frame.add(arithSymbolArea);

        digitalArea.setLayout(gBagLayout);
        initDigitalArea();
        frame.add(digitalArea, BorderLayout.EAST);

        frame.addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
                // TODO Auto-generated method stub
                super.windowClosing(e);
                System.exit(0);
            }
        });

            frame.pack();
            frame.setVisible(true);
        }

    private void initDigitalArea() {

        JButton mc = new JButton("mc");
        JButton mplus = new JButton("m+");
        JButton mminus = new JButton("m-");
        JButton mr = new JButton("mr");

        JButton ac = new JButton("AC");
        JButton pn = new JButton("+/-");
        JButton divide = new JButton("÷");
        JButton times = new JButton("×");
        JButton plus = new JButton("+");
        JButton minus = new JButton("-");
        JButton equal = new JButton("=");
        JButton dot = new JButton(".");
        for (int i = 0; i < 10; i++) {
            digitalButtons[i] = new JButton(String.valueOf(i));
        }

        gBagConstraints.fill = GridBagConstraints.BOTH;
        gBagConstraints.weightx = 1;
        addButton(mc);
        addButton(mplus);
        addButton(mminus);
        gBagConstraints.gridwidth = GridBagConstraints.REMAINDER;
        addButton(mr);

        gBagConstraints.gridwidth = 1;
        gBagConstraints.gridheight = 1;
        addButton(ac);
        addButton(pn);
        addButton(divide);
        gBagConstraints.gridwidth = GridBagConstraints.REMAINDER;
        addButton(times);

        gBagConstraints.gridwidth = 1;
        gBagConstraints.gridheight = 1;
        addButton(digitalButtons[7]);
        addButton(digitalButtons[8]);
        addButton(digitalButtons[9]);
        gBagConstraints.gridwidth = GridBagConstraints.REMAINDER;
        addButton(minus);

        gBagConstraints.gridwidth = 1;
        gBagConstraints.gridheight = 1;
        addButton(digitalButtons[4]);
        addButton(digitalButtons[5]);
        addButton(digitalButtons[6]);
        gBagConstraints.gridwidth = GridBagConstraints.REMAINDER;
        addButton(plus);

        gBagConstraints.gridwidth = 1;
        gBagConstraints.gridheight = 1;
        addButton(digitalButtons[1]);
        addButton(digitalButtons[2]);
        addButton(digitalButtons[3]);
        gBagConstraints.gridwidth = GridBagConstraints.REMAINDER;
        gBagConstraints.gridheight = 2;
        addButton(equal);

        gBagConstraints.gridheight = 1;
        gBagConstraints.gridwidth = 2;
        addButton(digitalButtons[0]);
        gBagConstraints.gridwidth = 1;
        addButton(dot);

    }

    private void addButton(JButton button) {
        gBagLayout.setConstraints(button, gBagConstraints);
        digitalArea.add(button);
    }

    public static void main(String[] args) {
        new MyCalculater().init();
    }


    private void calculate() {

    }



    class DigitalButton extends JButton {
        public DigitalButton() {
            // TODO Auto-generated constructor stub
            this.setBackground(new Color(0, 0, 0));
        }
    }

    class ArithSymbol extends JButton {
        public ArithSymbol() {
            // TODO Auto-generated constructor stub
            this.setBackground(new Color(128, 128, 128));
        }
    }

}

Answer 1

Try this one

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Frame;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.Insets;
import java.awt.Panel;
import java.awt.TextField;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

import javax.swing.JButton;

public class MyCalculater 
{
    private static final Insets insets = new Insets(0, 0, 0, 0);

    private Frame frame = new Frame("My-Calculator");
    private GridBagConstraints gBagConstraints = new GridBagConstraints();
    private GridBagLayout gBagLayout = new GridBagLayout();
    private Panel screen = new Panel();
    private Panel arithSymbolArea = new Panel();
    private Panel digitalArea = new Panel();
    private JButton[] digitalButtons = new JButton[10];

    public void init() {
        // Put a screen for output
        screen.add(new TextField(40));
        frame.add(screen, BorderLayout.NORTH);

        // To put the Arith symbols
        arithSymbolArea.setLayout(new GridLayout(6, 4));
        frame.add(arithSymbolArea);

        digitalArea.setLayout(gBagLayout);
        initDigitalArea();
        frame.add(digitalArea, BorderLayout.EAST);

        frame.addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
                // TODO Auto-generated method stub
                super.windowClosing(e);
                System.exit(0);
            }
        });

            frame.pack();
            frame.setVisible(true);
        }

    private void initDigitalArea() {

        JButton mc = new JButton("mc");
        JButton mplus = new JButton("m+");
        JButton mminus = new JButton("m-");
        JButton mr = new JButton("mr");

        JButton ac = new JButton("AC");
        JButton pn = new JButton("+/-");
        JButton divide = new JButton("÷");
        JButton times = new JButton("×");
        JButton plus = new JButton("+");
        JButton minus = new JButton("-");
        JButton equal = new JButton("=");
        JButton dot = new JButton(".");
        for (int i = 0; i < 10; i++) {
            digitalButtons[i] = new JButton(String.valueOf(i));
        }

        addComponent(mc, 0, 0, 1, 1, GridBagConstraints.CENTER, GridBagConstraints.BOTH);
        addComponent(mplus, 1, 0, 1, 1, GridBagConstraints.CENTER, GridBagConstraints.BOTH);
        addComponent(mminus, 2, 0, 1, 1, GridBagConstraints.CENTER, GridBagConstraints.BOTH);
        addComponent(mr, 3, 0, 1, 1, GridBagConstraints.CENTER, GridBagConstraints.BOTH);

        addComponent(ac, 0, 1, 1, 1, GridBagConstraints.CENTER, GridBagConstraints.BOTH);
        addComponent(pn, 1, 1, 1, 1, GridBagConstraints.CENTER, GridBagConstraints.BOTH);
        addComponent(divide, 2, 1, 1, 1, GridBagConstraints.CENTER, GridBagConstraints.BOTH);
        addComponent(times, 3, 1, 1, 1, GridBagConstraints.CENTER, GridBagConstraints.BOTH);

        addComponent(digitalButtons[7], 0, 2, 1, 1, GridBagConstraints.CENTER, GridBagConstraints.BOTH);
        addComponent(digitalButtons[8], 1, 2, 1, 1, GridBagConstraints.CENTER, GridBagConstraints.BOTH);
        addComponent(digitalButtons[9], 2, 2, 1, 1, GridBagConstraints.CENTER, GridBagConstraints.BOTH);
        addComponent(minus, 3, 2, 1, 1, GridBagConstraints.CENTER, GridBagConstraints.BOTH);

        addComponent(digitalButtons[4], 0, 3, 1, 1, GridBagConstraints.CENTER, GridBagConstraints.BOTH);
        addComponent(digitalButtons[5], 1, 3, 1, 1, GridBagConstraints.CENTER, GridBagConstraints.BOTH);
        addComponent(digitalButtons[6], 2, 3, 1, 1, GridBagConstraints.CENTER, GridBagConstraints.BOTH);
        addComponent(plus, 3, 3, 1, 1, GridBagConstraints.CENTER, GridBagConstraints.BOTH);

        addComponent(digitalButtons[1], 0, 4, 1, 1, GridBagConstraints.CENTER, GridBagConstraints.BOTH);
        addComponent(digitalButtons[2], 1, 4, 1, 1, GridBagConstraints.CENTER, GridBagConstraints.BOTH);
        addComponent(digitalButtons[3], 2, 4, 1, 1, GridBagConstraints.CENTER, GridBagConstraints.BOTH);
        addComponent(equal, 3, 4, 1, 2, GridBagConstraints.CENTER, GridBagConstraints.BOTH);

        addComponent(digitalButtons[0], 0, 5, 2, 1, GridBagConstraints.CENTER, GridBagConstraints.BOTH);
        addComponent(dot, 2, 5, 1, 2, GridBagConstraints.CENTER, GridBagConstraints.BOTH);

    }

    private  void addComponent(JButton button, int gridx, int gridy,
              int gridwidth, int gridheight, int anchor, int fill) {
            GridBagConstraints gbc = new GridBagConstraints(gridx, gridy, gridwidth, gridheight, 1.0, 1.0,
                anchor, fill, insets, 0, 0);
            gBagConstraints = gbc;
            addButton(button);
          }


    private void addButton(JButton button) {
        gBagLayout.setConstraints(button, gBagConstraints);
        digitalArea.add(button);
    }

    public static void main(String[] args) {
        new MyCalculater().init();
    }


    private void calculate() {

    }



    class DigitalButton extends JButton {
        public DigitalButton() {
            // TODO Auto-generated constructor stub
            this.setBackground(new Color(0, 0, 0));
        }
    }

    class ArithSymbol extends JButton {
        public ArithSymbol() {
            // TODO Auto-generated constructor stub
            this.setBackground(new Color(128, 128, 128));
        }
    }

}