How to resize buttons according to window size?

Question

I do not know how to make my buttons resizable, and I could not figure it out. I have tried to use:

frame.setLayout(new BorderLayout());
frame.add(panel, BorderLayout.CENTER);

This technically worked but not really, as it made the number buttons take all of the screen with no space for the text box or "(-)", "del", and "clr" buttons.

I really could not think of ways to do this, in python there is relative width/height which basically makes this a non issue, so how would I do something similar here?

package panda.org;

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class Calculator implements ActionListener{

    JFrame frame;
    JTextField textfield;
    JButton[] numberButtons = new JButton[10];
    JButton[] functionButtons = new JButton[9];
    JButton addButton,subButton,mulButton,divButton;
    JButton decButton, equButton, delButton, clrButton, negButton;
    JPanel panel;

    Font myFont = new Font("Serif Plain",Font.BOLD,30);

    double num1=0,num2=0,result=0;
    char operator;

    Calculator(){

        frame = new JFrame("Calculator");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(420, 550);
        frame.setLayout(null);
        frame.setLocationRelativeTo(null);
        frame.setResizable(true);
        Image icon = Toolkit.getDefaultToolkit().getImage("C:\\Users\\Gaming MSI\\Pictures\\Saved Pictures\\download.png");
        frame.setIconImage(icon);

        textfield = new JTextField();
        textfield.setBounds(50, 25, 300, 50);
        textfield.setFont(myFont);
        textfield.setEditable(false);

        addButton = new JButton("+");
        subButton = new JButton("-");
        mulButton = new JButton("x");
        divButton = new JButton("÷");
        decButton = new JButton(".");
        equButton = new JButton("=");
        delButton = new JButton("Del");
        clrButton = new JButton("Clr");
        negButton = new JButton("(-)");

        functionButtons[0] = addButton;
        functionButtons[1] = subButton;
        functionButtons[2] = mulButton;
        functionButtons[3] = divButton;
        functionButtons[4] = decButton;
        functionButtons[5] = equButton;
        functionButtons[6] = delButton;
        functionButtons[7] = clrButton;
        functionButtons[8] = negButton;

        for(int i =0;i<9;i++) {
            functionButtons[i].addActionListener(this);
            functionButtons[i].setFont(myFont);
            functionButtons[i].setFocusable(false);
        }

        for(int i =0;i<10;i++) {
            numberButtons[i] = new JButton(String.valueOf(i));
            numberButtons[i].addActionListener(this);
            numberButtons[i].setFont(myFont);
            numberButtons[i].setFocusable(false);
        }

        negButton.setBounds(50,430,100,50);
        delButton.setBounds(150,430,100,50);
        clrButton.setBounds(250,430,100,50);

        panel = new JPanel();
        panel.setBounds(50, 100, 300, 300);
        panel.setLayout(new GridLayout(4,4,10,10));

        panel.add(numberButtons[1]);
        panel.add(numberButtons[2]);
        panel.add(numberButtons[3]);
        panel.add(addButton);
        panel.add(numberButtons[4]);
        panel.add(numberButtons[5]);
        panel.add(numberButtons[6]);
        panel.add(subButton);
        panel.add(numberButtons[7]);
        panel.add(numberButtons[8]);
        panel.add(numberButtons[9]);
        panel.add(mulButton);
        panel.add(decButton);
        panel.add(numberButtons[0]);
        panel.add(equButton);
        panel.add(divButton);

        frame.add(panel);
        frame.add(negButton);
        frame.add(delButton);
        frame.add(clrButton);
        frame.add(textfield);
        frame.setVisible(true);
    }

    public static void main(String[] args) {

        Calculator calc = new Calculator();
    }

    @Override
    public void actionPerformed(ActionEvent e) {

        for(int i=0;i<10;i++) {
            if(e.getSource() == numberButtons[i]) {
                textfield.setText(textfield.getText().concat(String.valueOf(i)));
            }
        }
        if(e.getSource()==decButton) {
            textfield.setText(textfield.getText().concat("."));
        }
        if(e.getSource()==addButton) {
            num1 = Double.parseDouble(textfield.getText());
            operator ='+';
            textfield.setText("");
        }
        if(e.getSource()==subButton) {
            num1 = Double.parseDouble(textfield.getText());
            operator ='-';
            textfield.setText("");
        }
        if(e.getSource()==mulButton) {
            num1 = Double.parseDouble(textfield.getText());
            operator ='*';
            textfield.setText("");
        }
        if(e.getSource()==divButton) {
            num1 = Double.parseDouble(textfield.getText());
            operator ='/';
            textfield.setText("");
        }
        if(e.getSource()==equButton) {
            num2=Double.parseDouble(textfield.getText());

            switch(operator) {
                case'+':
                    result=num1+num2;
                    break;
                case'-':
                    result=num1-num2;
                    break;
                case'*':
                    result=num1*num2;
                    break;
                case'/':
                    result=num1/num2;
                    break;
            }
            textfield.setText(String.valueOf(result));
            num1=result;
        }
        if(e.getSource()==clrButton) {
            textfield.setText("");
        }
        if(e.getSource()==delButton) {
            String string = textfield.getText();
            textfield.setText("");
            for(int i=0;i<string.length()-1;i++) {
                textfield.setText(textfield.getText()+string.charAt(i));
            }
        }
        if(e.getSource()==negButton) {
            double temp = Double.parseDouble(textfield.getText());
            temp*=-1;
            textfield.setText(String.valueOf(temp));
        }
    }
}

Are you sure you want to use the null-layout? Check other questions like https://stackoverflow.com/questions/21242626/whats-wrong-with-the-null-layout-in-java and consider removing the null-layout and `setBounds()` calls. Let the layout managers arrange the components, don't do it yourself. — Progman, Apr 25 '21 at 08:54
Make use of an approbate layout manager - like `GridBagLayout` for example — MadProgrammer, Apr 25 '21 at 09:17

score 2 · Accepted Answer · answered Apr 25 '21 at 09:28

You're not stuck to one layout manager, in fact, the panel containing the buttons is a really good use of compound layout managers, where the button panel is focusing on one job, but which allows it to be integrated into another layout as required.

This is a really basic example which makes use of a GridBagLayout is the outer layout manager. You could also add the function buttons to their own panel and adjust their layout independently based on your needs.

import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.Image;
import java.awt.Insets;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.border.EmptyBorder;

public class Calculator implements ActionListener {

    JFrame frame;
    JTextField textfield;
    JButton[] numberButtons = new JButton[10];
    JButton[] functionButtons = new JButton[9];
    JButton addButton, subButton, mulButton, divButton;
    JButton decButton, equButton, delButton, clrButton, negButton;
    JPanel panel;

    Font myFont = new Font("Serif Plain", Font.BOLD, 30);

    double num1 = 0, num2 = 0, result = 0;
    char operator;

    Calculator() {

        frame = new JFrame("Calculator");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(420, 550);
        frame.setLocationRelativeTo(null);
        frame.setResizable(true);
        Image icon = Toolkit.getDefaultToolkit().getImage("C:\\Users\\Gaming MSI\\Pictures\\Saved Pictures\\download.png");
        frame.setIconImage(icon);

        textfield = new JTextField();
//        textfield.setBounds(50, 25, 300, 50);
        textfield.setFont(myFont);
        textfield.setEditable(false);

        addButton = new JButton("+");
        subButton = new JButton("-");
        mulButton = new JButton("x");
        divButton = new JButton("÷");
        decButton = new JButton(".");
        equButton = new JButton("=");
        delButton = new JButton("Del");
        clrButton = new JButton("Clr");
        negButton = new JButton("(-)");

        functionButtons[0] = addButton;
        functionButtons[1] = subButton;
        functionButtons[2] = mulButton;
        functionButtons[3] = divButton;
        functionButtons[4] = decButton;
        functionButtons[5] = equButton;
        functionButtons[6] = delButton;
        functionButtons[7] = clrButton;
        functionButtons[8] = negButton;

        for (int i = 0; i < 9; i++) {
            functionButtons[i].addActionListener(this);
            functionButtons[i].setFont(myFont);
            functionButtons[i].setFocusable(false);
        }

        for (int i = 0; i < 10; i++) {
            numberButtons[i] = new JButton(String.valueOf(i));
            numberButtons[i].addActionListener(this);
            numberButtons[i].setFont(myFont);
            numberButtons[i].setFocusable(false);
        }

//        negButton.setBounds(50, 430, 100, 50);
//        delButton.setBounds(150, 430, 100, 50);
//        clrButton.setBounds(250, 430, 100, 50);

        JPanel contentPane = new JPanel(new GridBagLayout());
        contentPane.setBorder(new EmptyBorder(10, 10, 10, 10));
        frame.setContentPane(contentPane);

        GridBagConstraints gbc = new GridBagConstraints();
        gbc.fill = GridBagConstraints.BOTH;
        gbc.gridwidth = gbc.REMAINDER;
        gbc.insets = new Insets(4, 4, 4, 4);
        gbc.weightx = 1;

        frame.add(textfield, gbc);

        panel = new JPanel();
        panel.setLayout(new GridLayout(4, 4, 10, 10));

        panel.add(numberButtons[1]);
        panel.add(numberButtons[2]);
        panel.add(numberButtons[3]);
        panel.add(addButton);
        panel.add(numberButtons[4]);
        panel.add(numberButtons[5]);
        panel.add(numberButtons[6]);
        panel.add(subButton);
        panel.add(numberButtons[7]);
        panel.add(numberButtons[8]);
        panel.add(numberButtons[9]);
        panel.add(mulButton);
        panel.add(decButton);
        panel.add(numberButtons[0]);
        panel.add(equButton);
        panel.add(divButton);

        gbc.weighty = 1;
        frame.add(panel, gbc);

        // These could be in their own panel
        // as well!

        gbc = new GridBagConstraints();
        gbc.gridx = 0;
        gbc.gridwidth = 1;
        gbc.weightx = 0.3;

        frame.add(negButton, gbc);
        gbc.gridx++;
        frame.add(delButton, gbc);
        gbc.gridx++;
        frame.add(clrButton, gbc);

        frame.setVisible(true);
    }

    public static void main(String[] args) {

        Calculator calc = new Calculator();
    }

    @Override
    public void actionPerformed(ActionEvent e) {

        for (int i = 0; i < 10; i++) {
            if (e.getSource() == numberButtons[i]) {
                textfield.setText(textfield.getText().concat(String.valueOf(i)));
            }
        }
        if (e.getSource() == decButton) {
            textfield.setText(textfield.getText().concat("."));
        }
        if (e.getSource() == addButton) {
            num1 = Double.parseDouble(textfield.getText());
            operator = '+';
            textfield.setText("");
        }
        if (e.getSource() == subButton) {
            num1 = Double.parseDouble(textfield.getText());
            operator = '-';
            textfield.setText("");
        }
        if (e.getSource() == mulButton) {
            num1 = Double.parseDouble(textfield.getText());
            operator = '*';
            textfield.setText("");
        }
        if (e.getSource() == divButton) {
            num1 = Double.parseDouble(textfield.getText());
            operator = '/';
            textfield.setText("");
        }
        if (e.getSource() == equButton) {
            num2 = Double.parseDouble(textfield.getText());

            switch (operator) {
                case '+':
                    result = num1 + num2;
                    break;
                case '-':
                    result = num1 - num2;
                    break;
                case '*':
                    result = num1 * num2;
                    break;
                case '/':
                    result = num1 / num2;
                    break;
            }
            textfield.setText(String.valueOf(result));
            num1 = result;
        }
        if (e.getSource() == clrButton) {
            textfield.setText("");
        }
        if (e.getSource() == delButton) {
            String string = textfield.getText();
            textfield.setText("");
            for (int i = 0; i < string.length() - 1; i++) {
                textfield.setText(textfield.getText() + string.charAt(i));
            }
        }
        if (e.getSource() == negButton) {
            double temp = Double.parseDouble(textfield.getText());
            temp *= -1;
            textfield.setText(String.valueOf(temp));
        }
    }
}

Take a look at Laying Out Components Within a Container for more details

How to resize buttons according to window size?

1 Answers1