import java.awt.BorderLayout;
import java.awt.Button;
import java.awt.Container;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JApplet;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class PopupCalculatorApplet extends JApplet implements ActionListener {
  public void init() {
    Button calcButton = new Button("Calculator");
    calcButton.addActionListener(this);
    Container contentPane = getContentPane();
    contentPane.add(calcButton);
  }

  public void actionPerformed(ActionEvent evt) {
    if (calc.isVisible())
      calc.setVisible(false);
    else
      calc.show();
  }

  private JFrame calc = new CalculatorFrame();
}

class CalculatorPanel extends JPanel implements ActionListener {
  public CalculatorPanel() {
    setLayout(new BorderLayout());

    display = new JTextField("0");
    display.setEditable(false);
    add(display, "North");

    JPanel p = new JPanel();
    p.setLayout(new GridLayout(4, 4));
    String buttons = "789/456*123-0.=+";
    for (int i = 0; i < buttons.length(); i++)
      addButton(p, buttons.substring(i, i + 1));
    add(p, "Center");
  }

  private void addButton(Container c, String s) {
    JButton b = new JButton(s);
    c.add(b);
    b.addActionListener(this);
  }

  public void actionPerformed(ActionEvent evt) {
    String s = evt.getActionCommand();
    if ('0' <= s.charAt(0) && s.charAt(0) <= '9' || s.equals(".")) {
      if (start)
        display.setText(s);
      else
        display.setText(display.getText() + s);
      start = false;
    } else {
      if (start) {
        if (s.equals("-")) {
          display.setText(s);
          start = false;
        } else
          op = s;
      } else {
        calculate(Double.parseDouble(display.getText()));
        op = s;
        start = true;
      }
    }
  }

  public void calculate(double n) {
    if (op.equals("+"))
      arg += n;
    else if (op.equals("-"))
      arg -= n;
    else if (op.equals("*"))
      arg *= n;
    else if (op.equals("/"))
      arg /= n;
    else if (op.equals("="))
      arg = n;
    display.setText("" + arg);
  }

  private JTextField display;

  private double arg = 0;

  private String op = "=";

  private boolean start = true;
}

class CalculatorFrame extends JFrame {
  public CalculatorFrame() {
    setTitle("Calculator");
    setSize(200, 200);

    Container contentPane = getContentPane();
    contentPane.add(new CalculatorPanel());
  }
}

The post Java Program for calculator first appeared on Student Projects.

import java.awt.*;
import java.awt.event.*;
import java.applet.*;

/* 


*/

public class Cal extends Applet
implements ActionListener
{
	String msg=" ";
	int v1,v2,result;
	TextField t1;
	Button b[]=new Button[10];
	Button add,sub,mul,div,clear,mod,EQ;
	char OP;
	public void init()
	{
		Color k=new Color(120,89,90);
		setBackground(k);
		t1=new TextField(10);
		GridLayout gl=new GridLayout(4,5);
		setLayout(gl);
		for(int i=0;i<10;i++)
		{
			b[i]=new Button(""+i);
		}
		add=new Button("add");
		sub=new Button("sub");
		mul=new Button("mul");
		div=new Button("div");
		mod=new Button("mod");
		clear=new Button("clear");
		EQ=new Button("EQ");
		t1.addActionListener(this);
		add(t1);
		for(int i=0;i<10;i++)
		{
			add(b[i]);
		}
		add(add);
		add(sub);
		add(mul);
		add(div);
		add(mod);
		add(clear);
		add(EQ);
		for(int i=0;i<10;i++)
		{
			b[i].addActionListener(this);
		}
		add.addActionListener(this);
		sub.addActionListener(this);
		mul.addActionListener(this);
		div.addActionListener(this);
		mod.addActionListener(this);
		clear.addActionListener(this);
		EQ.addActionListener(this);
	}

	public void actionPerformed(ActionEvent ae)
	{
		String str=ae.getActionCommand();
		char ch=str.charAt(0);
		if ( Character.isDigit(ch))
		t1.setText(t1.getText()+str);
		else
		if(str.equals("add"))
		{
			v1=Integer.parseInt(t1.getText());
			OP='+';
			t1.setText("");
		}
		else if(str.equals("sub"))
		{
			v1=Integer.parseInt(t1.getText());
			OP='-';
			t1.setText("");
		}
		else if(str.equals("mul"))
		{
			v1=Integer.parseInt(t1.getText());
			OP='*';
			t1.setText("");
		}
		else if(str.equals("div"))
		{
			v1=Integer.parseInt(t1.getText());
			OP='/';
			t1.setText("");
		}
		else if(str.equals("mod"))
		{
			v1=Integer.parseInt(t1.getText());
			OP='%';
			t1.setText("");
		}
		if(str.equals("EQ"))
		{
			v2=Integer.parseInt(t1.getText());
			if(OP=='+')
				result=v1+v2;
			else if(OP=='-')
				result=v1-v2;
			else if(OP=='*')
				result=v1*v2;
			else if(OP=='/')
				result=v1/v2;
			else if(OP=='%')
				result=v1%v2;
			t1.setText(""+result);
		}	
		if(str.equals("clear"))
		{
			t1.setText("");
		}
	}
}

Output:

The post Java applet program for calculator first appeared on Student Projects.