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How to design a calculator which performs arithmetic operations using swings?
Asked by Nandini Last Modified
Answer 
Debadi Prasanna Gongopadhyay
I am an IT Professional with having 5years of teaching(1000+ students in Kolkata)
// 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 oprerator and operands String s0, s1, s2; // default constrcutor 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); } } } View 1 more Answers
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