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 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 elementsimport 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.
