Java Swing | Simple Calculator

16 Apr, 2021
Java Swing is a GUI (graphical user Interface) widget toolkit for Java. Java Swing is a part of Oracle’s Java foundation classes . Java Swing is an API for providing graphical user interface elements to Java Programs.Swing was created to provide more powerful and flexible components than Java AWT (Abstract Window Toolkit).In this article we will use Java Swing components to create a simple calculator with only +, -, /, * operations.methods used :  
add(Component c) : adds component to container.addActionListenerListener(ActionListener d) : add actionListener for specified componentsetBackground(Color c) : sets the background color of the specified containersetSize(int a, int b) : sets the size of container to specified dimensions.setText(String s) : sets the text of the label to s.getText() : returns the text of the label.
add(Component c) : adds component to container.
addActionListenerListener(ActionListener d) : add actionListener for specified component
setBackground(Color c) : sets the background color of the specified container
setSize(int a, int b) : sets the size of container to specified dimensions.
setText(String s) : sets the text of the label to s.
getText() : returns the text of the label.
Java program to create a simple calculator with basic +, -, /, * using java swing elements.  
Java
// Java program to create a simple calculator// with basic +, -, /, * using java swing elements import java.awt.event.*;import javax.swing.*;import java.awt.*;class calculator extends JFrame implements ActionListener {    // create a frame    static JFrame f;     // create a textfield    static JTextField l;     // store operator and operands    String s0, s1, s2;     // default constructor    calculator()    {        s0 = s1 = s2 = "";    }     // main function    public static void main(String args[])    {        // create a frame        f = new JFrame("calculator");         try {            // set look and feel            UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());        }        catch (Exception e) {            System.err.println(e.getMessage());        }         // create a object of class        calculator c = new calculator();         // create a textfield        l = new JTextField(16);         // set the textfield to non editable        l.setEditable(false);         // create number buttons and some operators        JButton b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, ba, bs, bd, bm, be, beq, beq1;         // create number buttons        b0 = new JButton("0");        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");         // equals button        beq1 = new JButton("=");         // create operator buttons        ba = new JButton("+");        bs = new JButton("-");        bd = new JButton("/");        bm = new JButton("*");        beq = new JButton("C");         // create . button        be = new JButton(".");         // create a panel        JPanel p = new JPanel();         // add action listeners        bm.addActionListener(c);        bd.addActionListener(c);        bs.addActionListener(c);        ba.addActionListener(c);        b9.addActionListener(c);        b8.addActionListener(c);        b7.addActionListener(c);        b6.addActionListener(c);        b5.addActionListener(c);        b4.addActionListener(c);        b3.addActionListener(c);        b2.addActionListener(c);        b1.addActionListener(c);        b0.addActionListener(c);        be.addActionListener(c);        beq.addActionListener(c);        beq1.addActionListener(c);         // add elements to panel        p.add(l);        p.add(ba);        p.add(b1);        p.add(b2);        p.add(b3);        p.add(bs);        p.add(b4);        p.add(b5);        p.add(b6);        p.add(bm);        p.add(b7);        p.add(b8);        p.add(b9);        p.add(bd);        p.add(be);        p.add(b0);        p.add(beq);        p.add(beq1);         // set Background of panel        p.setBackground(Color.blue);         // add panel to frame        f.add(p);         f.setSize(200, 220);        f.show();    }    public void actionPerformed(ActionEvent e)    {        String s = e.getActionCommand();         // if the value is a number        if ((s.charAt(0) >= '0' && s.charAt(0) <= '9') || s.charAt(0) == '.') {            // if operand is present then add to second no            if (!s1.equals(""))                s2 = s2 + s;            else                s0 = s0 + s;             // set the value of text            l.setText(s0 + s1 + s2);        }        else if (s.charAt(0) == 'C') {            // clear the one letter            s0 = s1 = s2 = "";             // set the value of text            l.setText(s0 + s1 + s2);        }        else if (s.charAt(0) == '=') {             double te;             // store the value in 1st            if (s1.equals("+"))                te = (Double.parseDouble(s0) + Double.parseDouble(s2));            else if (s1.equals("-"))                te = (Double.parseDouble(s0) - Double.parseDouble(s2));            else if (s1.equals("/"))                te = (Double.parseDouble(s0) / Double.parseDouble(s2));            else                te = (Double.parseDouble(s0) * Double.parseDouble(s2));             // set the value of text            l.setText(s0 + s1 + s2 + "=" + te);             // convert it to string            s0 = Double.toString(te);             s1 = s2 = "";        }        else {            // if there was no operand            if (s1.equals("") || s2.equals(""))                s1 = s;            // else evaluate            else {                double te;                 // store the value in 1st                if (s1.equals("+"))                    te = (Double.parseDouble(s0) + Double.parseDouble(s2));                else if (s1.equals("-"))                    te = (Double.parseDouble(s0) - Double.parseDouble(s2));                else if (s1.equals("/"))                    te = (Double.parseDouble(s0) / Double.parseDouble(s2));                else                    te = (Double.parseDouble(s0) * Double.parseDouble(s2));                 // convert it to string                s0 = Double.toString(te);                 // place the operator                s1 = s;                 // make the operand blank                s2 = "";            }             // set the value of text            l.setText(s0 + s1 + s2);        }    }}
Output :  
 
Note : this program might not run in an online compiler please use an offline IDE. 
sweetyty
java-swing
Java
Java
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