Answer to Question #269279 in Java | JSP | JSF for liza

Question

Create a frame. Place two textboxes in the frame using any appropriate layout. Then place four buttons with the button title +, -, * and /. If the user should put two numeric values in the text fields and click any of the button, then a corresponding calculation ( addition, subtraction, multiplication or division) should be shown in a JOptionPane Message Dialogue popup. If the user mistakenly provides any non numerical values in the textbox then a message "Input should be numerical. Please try again" should be shown in a 

JOptionPane Message Dialogue popup.

An example program if only addition and subtraction buttons has been given attached. It doesn't check for wrong input type. In your submission you must check for wrong input type and a message should be displayed accordingly

Answer 1

import java.awt.event.*;
import javax.swing.*;
import java.awt.*;
class calculator extends JFrame implements ActionListener {
	static JFrame f;
	calculator()
	{
		s0 = s1 = s2 = "";
	}


	public static void main(String args[])
	{
		f = new JFrame("calculator");
		try {
			UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
		}
		catch (Exception e) {
			System.err.println(e.getMessage());
		}
		calculator c = new calculator();
		l = new JTextField(16);
		l.setEditable(false);
		JButton b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, ba, bs, bd, bm, be, beq, beq1;
		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");
		beq1 = new JButton("=");
		ba = new JButton("+");
		bs = new JButton("-");
		bd = new JButton("/");
		bm = new JButton("*");
		beq = new JButton("C");
		be = new JButton(".");
		JPanel p = new JPanel();
		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);
		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);
		p.setBackground(Color.blue);
		f.add(p);
		f.setSize(200, 220);
		f.show();
	}
	public void actionPerformed(ActionEvent e)
	{
		String s = e.getActionCommand();
		if ((s.charAt(0) >= '0' && s.charAt(0) <= '9') || s.charAt(0) == '.') {
			if (!s1.equals(""))
				s2 = s2 + s;
			else
				s0 = s0 + s;
			l.setText(s0 + s1 + s2);
		}
		else if (s.charAt(0) == 'C') {
			s0 = s1 = s2 = "";
			l.setText(s0 + s1 + s2);
		}
		else if (s.charAt(0) == '=') {
			double te;
			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));
			l.setText(s0 + s1 + s2 + "=" + te);
			s0 = Double.toString(te);
			s1 = s2 = "";
		}
		else {
			if (s1.equals("") || s2.equals(""))
				s1 = s;
			else {
				double te;
				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));
				s0 = Double.toString(te);
				s1 = s;
				s2 = "";
			}
			l.setText(s0 + s1 + s2);
		}
	}
}