JavaCalculatorUI.java

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

class Calc implements ActionListener {
    JFrame f;

    JTextField t;
    JButton b1, b2, b3, b4, b5, b6, b7, b8, b9, b0, bdiv, bmul, bsub, badd, bdec, beq, bdel, bclr;

    static double a = 0, b = 0, result = 0;
    static int operator = 0;

    Calc() {
        // setting title on the window
        f = new JFrame("Calculator");
        t = new JTextField();

        // initializing all the buttons of the calculator
        b1 = new JButton("1");
        b2 = new JButton("2");
        b3 = new JButton("3");
        b4 = new JButton("4");
        b5 = new JButton("5");
        b6 = new JButton("6");
        b7 = new JButton("7");
        b8 = new JButton("8");
        b9 = new JButton("9");
        b0 = new JButton("0");
        bdiv = new JButton("/");
        bmul = new JButton("*");
        bsub = new JButton("-");
        badd = new JButton("+");
        bdec = new JButton(".");
        beq = new JButton("=");
        bdel = new JButton("Delete");
        bclr = new JButton("Clear");

        // setting the size all each button and their co-ordinates
        t.setBounds(30, 40, 280, 30);
        b7.setBounds(40, 100, 50, 40);
        b8.setBounds(110, 100, 50, 40);
        b9.setBounds(180, 100, 50, 40);
        bdiv.setBounds(250, 100, 50, 40);
        b4.setBounds(40, 170, 50, 40);
        b5.setBounds(110, 170, 50, 40);
        b6.setBounds(180, 170, 50, 40);
        bmul.setBounds(250, 170, 50, 40);
        b1.setBounds(40, 240, 50, 40);
        b2.setBounds(110, 240, 50, 40);
        b3.setBounds(180, 240, 50, 40);
        bsub.setBounds(250, 240, 50, 40);
        bdec.setBounds(40, 310, 50, 40);
        b0.setBounds(110, 310, 50, 40);
        beq.setBounds(180, 310, 50, 40);
        badd.setBounds(250, 310, 50, 40);
        bdel.setBounds(60, 380, 100, 40);
        bclr.setBounds(180, 380, 100, 40);

        // adding all of them to the JFrame Window
        f.add(t);
        f.add(b7);
        f.add(b8);
        f.add(b9);
        f.add(bdiv);
        f.add(b4);
        f.add(b5);
        f.add(b6);
        f.add(bmul);
        f.add(b1);
        f.add(b2);
        f.add(b3);
        f.add(bsub);
        f.add(bdec);
        f.add(b0);
        f.add(beq);
        f.add(badd);
        f.add(bdel);
        f.add(bclr);

        // setting layout
        f.setLayout(null);

        // setting the visibility
        f.setVisible(true);

        // setting the window size
        f.setSize(350, 500);

        // adding close functionality to the window
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        // making the size of the window non-changeable
        f.setResizable(false);

        // adding action listeners to each of the buttons
        b1.addActionListener(this);
        b2.addActionListener(this);
        b3.addActionListener(this);
        b4.addActionListener(this);
        b5.addActionListener(this);
        b6.addActionListener(this);
        b7.addActionListener(this);
        b8.addActionListener(this);
        b9.addActionListener(this);
        b0.addActionListener(this);
        badd.addActionListener(this);
        bdiv.addActionListener(this);
        bmul.addActionListener(this);
        bsub.addActionListener(this);
        bdec.addActionListener(this);
        beq.addActionListener(this);
        bdel.addActionListener(this);
        bclr.addActionListener(this);
    }

    // adding functionalities to the buttons
    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == b1)
            t.setText(t.getText().concat("1"));
        if (e.getSource() == b2)
            t.setText(t.getText().concat("2"));
        if (e.getSource() == b3)

            t.setText(t.getText().concat("3"));
        if (e.getSource() == b4)
            t.setText(t.getText().concat("4"));
        if (e.getSource() == b5)
            t.setText(t.getText().concat("5"));
        if (e.getSource() == b6)
            t.setText(t.getText().concat("6"));
        if (e.getSource() == b7)
            t.setText(t.getText().concat("7"));
        if (e.getSource() == b8)
            t.setText(t.getText().concat("8"));
        if (e.getSource() == b9)
            t.setText(t.getText().concat("9"));
        if (e.getSource() == b0)
            t.setText(t.getText().concat("0"));
        if (e.getSource() == bdec)
            t.setText(t.getText().concat("."));
        if (e.getSource() == badd) {
            a = Double.parseDouble(t.getText());
            operator = 1;
            t.setText("");
        }
        if (e.getSource() == bsub) {
            a = Double.parseDouble(t.getText());

            operator = 2;
            t.setText("");
        }
        if (e.getSource() == bmul) {
            a = Double.parseDouble(t.getText());
            operator = 3;
            t.setText("");
        }
        if (e.getSource() == bdiv) {
            a = Double.parseDouble(t.getText());
            operator = 4;
            t.setText("");
        }

        // calculation performing logic
        if (e.getSource() == beq) {
            b = Double.parseDouble(t.getText());
            switch (operator) {
                case 1:
                    result = a + b;
                    break;
                case 2:
                    result = a - b;
                    break;
                case 3:
                    result = a * b;
                    break;
                case 4:
                    result = a / b;
                    break;
                default:
                    result = 0;
            }
            // setting the textfield with the result obtained post calculation
            t.setText("" + result);
        }

        // clearing textfield on clicking of clr button
        if (e.getSource() == bclr)
            t.setText("");

        // adding functionality to the delete button
        if (e.getSource() == bdel) {
            String s = t.getText();
            t.setText("");
            for (int i = 0; i < s.length() - 1; i++)
                t.setText(t.getText() + s.charAt(i));
        }
    }

    // Driver Method
    public static void main(String... s) {
        new Calc();
    }
}