Probably I would have posted this few years ago (7 years precisely) as I've developed this long ago. Just got a chance and thought that this might be helpful for few programmers out there.
This program is based on the Java awt (Abstract Window Toolkit) extension Java Swings.
Calculator.java
/**
* Basic Calculator
* @author SANTHOSH REDDY MANDADI
* @since 20-April-2006
* @version 1.0
*/
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Calculator extends JFrame implements ActionListener,Runnable
{
JButton bnum[];
JButton bback,bce,bc;
JButton bop[],jdb;
JLabel jl;
JTextField tf;
JPanel p1,p2,p3;
JDialog jd;
double d1,d2,d3;
//long n1,n2,n3;
boolean frac=false;
char op;
boolean opc=false,ope=false;
public void run()
{
while(true)
{
char ch=getTitle().charAt(0);
setTitle(getTitle().substring(1,getTitle().length())+Character.toString(ch));
try{
Thread.sleep(200);
}catch(InterruptedException ie){
System.out.println(ie);
}
}
}
public Calculator(String str)
{
super(str);
bnum=new JButton[10];
jd=new JDialog(this,"Message",true);
jdb=new JButton("OK");
jl=new JLabel();
jd.setLayout(new FlowLayout());
jdb.setMargin(new Insets(2,5,2,5));
jd.add(jl); jd.add(jdb);
jdb.addActionListener(this);
for(int i=0;i<10;i++)
bnum[i]=new JButton(Integer.toString(i));
bback=new JButton("Back");
bce=new JButton("CE");
bc=new JButton("C");
p2=new JPanel();
p2.setLayout(new FlowLayout());
p2.add(bback);
p2.add(bce);
p2.add(bc);
tf=new JTextField(15);
p1=new JPanel();
p1.add(tf);
tf.setEditable(false);
tf.setHorizontalAlignment(JTextField.RIGHT);
tf.setText("0.");
tf.setBackground(Color.white);
tf.setFont(new Font("Dialog",Font.BOLD,12));
//System.out.println(tf.getFont());
bop=new JButton[10];
bop[0]=new JButton("+");
bop[1]=new JButton("-");
bop[2]=new JButton("*");
bop[3]=new JButton("/");
bop[4]=new JButton(".");
bop[5]=new JButton("=");
bop[6]=new JButton("%");
bop[7]=new JButton("Sqrt");
bop[8]=new JButton("1/x");
bop[9]=new JButton("+/-");
for(int i=0;i<10;i++){
bop[i].setMargin(new Insets(2,2,2,2));
bop[i].addActionListener(this);
}
p3=new JPanel();
p3.setLayout(new GridLayout(4,5,5,5));
p3.add(bnum[1]);
p3.add(bnum[2]);
p3.add(bnum[3]);
p3.add(bop[0]);
p3.add(bop[7]);
p3.add(bnum[4]);
p3.add(bnum[5]);
p3.add(bnum[6]);
p3.add(bop[1]);
p3.add(bop[8]);
p3.add(bnum[7]);
p3.add(bnum[8]);
p3.add(bnum[9]);
p3.add(bop[2]);
p3.add(bop[6]);
p3.add(bnum[0]);
p3.add(bop[9]);
p3.add(bop[4]);
p3.add(bop[3]);
p3.add(bop[5]);
Container c=getContentPane();
c.setLayout(new FlowLayout());
c.add(p1);
c.add(p2);
c.add(p3);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setResizable(false);
for(int i=0;i<=6;i++)
bop[i].setFont(new Font("Dialog",Font.BOLD,13));
for(int i=0;i<10;i++){
bnum[i].addActionListener(this);
bnum[i].setMargin(new Insets(2,10,2,10));
}
bce.addActionListener(this);
bc.addActionListener(this);
bback.addActionListener(this);
}
public void actionPerformed(ActionEvent ae)
{
String s=tf.getText();
String str;
if(!frac)
str=s.substring(0,s.length()-1);
else
str=s;
if(ae.getSource()==bback)
{
if(frac){
if(str.charAt(str.length()-1)=='.')
frac=false;
else tf.setText(str.substring(0,str.length()-1));
}
else{
if(!str.equals("0"))
tf.setText(str.substring(0,str.length()-1)+".");
}
if(tf.getText().equals("."))
tf.setText("0.");
}
else if(ae.getSource()==bce)
{
tf.setText("0.");
frac=false;
opc=false;
}
else if(ae.getSource()==bc)
{
tf.setText("0.");
d1=0;
d2=0;
frac=false;
opc=false;
ope=false;
}
else if(ae.getSource()==bop[0])
{
if(ope){
d2=Double.parseDouble(str);
d3=calc(d1,d2,op);
String dn=Double.toString(d3);
if(dn.charAt(dn.length()-1)=='0')
dn=dn.substring(0,dn.length()-1);
tf.setText(dn);
ope=false;
str=dn;
}
d1=Double.parseDouble(str);
opc=true;
op='+';
}
else if(ae.getSource()==bop[1])
{
if(ope){
d2=Double.parseDouble(str);
d3=calc(d1,d2,op);
String dn=Double.toString(d3);
if(dn.charAt(dn.length()-1)=='0')
dn=dn.substring(0,dn.length()-1);
tf.setText(dn);
ope=false;
str=dn;
}
d1=Double.parseDouble(str);
opc=true;
op='-';
}
else if(ae.getSource()==bop[2])
{
if(ope){
d2=Double.parseDouble(str);
d3=calc(d1,d2,op);
String dn=Double.toString(d3);
if(dn.charAt(dn.length()-1)=='0')
dn=dn.substring(0,dn.length()-1);
tf.setText(dn);
ope=false;
str=dn;
}
d1=Double.parseDouble(str);
opc=true;
op='*';
}
else if(ae.getSource()==bop[3])
{
if(ope){
d2=Double.parseDouble(str);
d3=calc(d1,d2,op);
String dn=Double.toString(d3);
if(dn.charAt(dn.length()-1)=='0')
dn=dn.substring(0,dn.length()-1);
tf.setText(dn);
ope=false;
str=dn;
}
d1=Double.parseDouble(str);
opc=true;
op='/';
}
else if(ae.getSource()==bop[4])
{
frac=true;
}
else if(ae.getSource()==bop[5])
{
if(ope)
{
d2=Double.parseDouble(str);
d3=calc(d1,d2,op);
String dn=Double.toString(d3);
if(dn.charAt(dn.length()-1)=='0')
dn=dn.substring(0,dn.length()-1);
tf.setText(dn);
d1=d3;
opc=false;
ope=false;
}
}
else if(ae.getSource()==bop[6])
{
if(ope)
{
double temp=Double.parseDouble(tf.getText());
String tmp=Double.toString(d1*temp/100);
if(tmp.charAt(tmp.length()-1)=='0')
tmp=tmp.substring(0,tmp.length()-1);
tf.setText(tmp);
}
else
tf.setText("0.");
}
else if(ae.getSource()==bop[7])
{
double temp=Double.parseDouble(tf.getText());
String tmp=Double.toString(Math.sqrt(temp));
if(tmp.charAt(tmp.length()-1)=='0')
tmp=tmp.substring(0,tmp.length()-1);
tf.setText(tmp);
}
else if(ae.getSource()==bop[8])
{
double temp=Double.parseDouble(tf.getText());
String tmp=Double.toString(1/temp);
if(tmp.equals("Infinity")){
jl.setText("Cannot divided by zero");
jd.setSize(150,90);
jd.setResizable(false);
jd.setVisible(true);
}
else{
if(tmp.charAt(tmp.length()-1)=='0')
tmp=tmp.substring(0,tmp.length()-1);
tf.setText(tmp);
}
}
else if(ae.getSource()==bop[9])
{
double temp=Double.parseDouble(tf.getText());
if(temp!=0){
String tmp=Double.toString(-1*temp);
if(tmp.charAt(tmp.length()-1)=='0')
tmp=tmp.substring(0,tmp.length()-1);
tf.setText(tmp);
}else tf.setText("0.");
}
else if(ae.getSource()==jdb)
{
jd.setVisible(false);
}
else
{
if(opc){
tf.setText("0.");
frac=false;
str="0";
ope=true;
opc=false;
}
if(frac)
tf.setText(str+ae.getActionCommand());
else{
if(str.equals("0")){
tf.setText("");
tf.setText(ae.getActionCommand()+".");
}
else
tf.setText(str+ae.getActionCommand()+".");
}
}
}
public double calc(double a,double b,char ch)
{
double c=0;
switch(ch)
{
case '+':
c=a+b;
break;
case '-':
c=a-b;
break;
case '*':
c=a*b;
break;
case '/':
c=a/b;
break;
}
return c;
}
public static void main(String[] args)
{
Calculator c=new Calculator("Calculator ");
c.setSize(210,250);
c.setVisible(true);
Thread t=new Thread(c);
t.start();
}
}
This has been tested on Java 1.4 and 1.5 versions of Sun Microsystem's Java.
Screenshot of the Calculator below...
If you've sometime, why don't you checkout my other Java programs.