Java Programming - Calculator in swing

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import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class GuiCalculator
{
String o="+";
double d1=0.0,d2=0.0;

JFrame jf;
Container c;
JTextField tf;
JButton b1,b2,b3,b4,b5,b6,b7,b8,b9,b10,b11,b12,b13,b14,b15,b16,b17;
public GuiCalculator()
{
jf=new JFrame("Calculator");
jf.setSize(400,500);
jf.setResizable(false);

jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
tf=new JTextField("",12);

c=jf.getContentPane();
//GridBagLayout gb=new GridBagLayout();
//gb.addLayoutComponent(tf);
c.setLayout(null);
tf.setColumns(12);
tf.setHorizontalAlignment(JTextField.RIGHT);
tf.setFont(new Font("Font.TIMESNEWROMAN",Font.BOLD,36));
c.add(tf);
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");
b10=new JButton("0");
b11=new JButton(".");
b12=new JButton("=");
b13=new JButton("+");
b14=new JButton("-");
b15=new JButton("x");
b16=new JButton("/");
b17=new JButton("");
tf.setBounds(20,10,330,50);
b1.setBounds(10,120,60,35);
b2.setBounds(110,120,60,35);
b3.setBounds(210,120,60,35);
b4.setBounds(310,120,60,35);
b5.setBounds(10,220,60,35);
b6.setBounds(110,220,60,35);
b7.setBounds(210,220,60,35);
b8.setBounds(310,220,60,35);
b9.setBounds(10,320,60,35);
b10.setBounds(110,320,60,35);
b11.setBounds(210,320,60,35);
b12.setBounds(310,320,60,35);
b13.setBounds(10,420,60,35);
b14.setBounds(110,420,60,35);
b15.setBounds(210,420,60,35);
b16.setBounds(310,420,60,35);
b17.setBounds(310,420,60,35);

//c.setLayout(new GridLayout(4,4));
b1.addActionListener(new Perform());
b2.addActionListener(new Perform());
b3.addActionListener(new Perform());
b4.addActionListener(new Perform());
b5.addActionListener(new Perform());
b6.addActionListener(new Perform());
b7.addActionListener(new Perform());
b8.addActionListener(new Perform());
b9.addActionListener(new Perform());
b10.addActionListener(new Perform());
b11.addActionListener(new Perform());
b12.addActionListener(new Perform());
b13.addActionListener(new Perform());
b14.addActionListener(new Perform());
b15.addActionListener(new Perform());
b16.addActionListener(new Perform());


c.add(b1);
c.add(b2);
c.add(b3);
c.add(b4);
c.add(b5);
c.add(b6);
c.add(b7);
c.add(b8);
c.add(b9);
c.add(b10);
c.add(b11);
c.add(b12);
c.add(b13);
c.add(b14);
c.add(b15);
c.add(b16);
c.add(b17);
jf.setVisible(true);


}

class Perform implements ActionListener
{
//String o="+";
//double d1=0.0,d2=0.0;

public void actionPerformed(ActionEvent e)
{
String s=e.getActionCommand();
int j=-1;
if(Character.isDigit(s.charAt(0)))
j=Integer.parseInt(s);
for(int i=0;i<=9;i++)
if(i==j)
tf.setText(tf.getText()+s);
if((s.equals("+"))||(s.equals("-"))||(s.equals("x"))||(s.equals("/")))
{
if(!(tf.getText().equals("")))
d1=Double.parseDouble(tf.getText());
o=s;
tf.setText("");
}
if(s.equals("="))
{
d2=Double.parseDouble(tf.getText());
if(o.equals("+"))
tf.setText(String.valueOf(d1+d2));
if(o.equals("-"))
tf.setText(String.valueOf(d1-d2));
if(o.equals("x"))
tf.setText(String.valueOf(d1*d2));
if(o.equals("/"))
tf.setText(String.valueOf(d1/d2));

}
}
}
public static void main(String args[])
{
GuiCalculator gui=new GuiCalculator();
}
}

java - simple calculator for add,sub in applet

/*first program in java, strating with basic applet program "calculator.java" compile it in DOS prompt as"c:\java\jdk1.5\bin\javac calculator.java" */
import java.awt.*;
import java.applet.*;
import java.awt.event.*;

public class calculator extends Applet implements ActionListener
{
Label l1,l2,l3,l4;
TextField t1,t2;
Button b1,b2,b3,b4;

public void init()
{
b1=new Button("add");
b2=new Button("sub");
b3=new Button("mul");
b4=new Button("div");
l1=new Label("number1");
l2=new Label("number2");
l3=new Label("result");
l4=new Label(" ");
t1=new TextField(22);
t2=new TextField(22);

add(l1);add(t1);add(l2);add(t2);add(l3);add(l4);add(b1);add(b2);
add(b3);add(b4);

b1.addActionListener(this);
b2.addActionListener(this);
b3.addActionListener(this);
b4.addActionListener(this);

}//init() closed

public void actionPerformed(ActionEvent ae)
{
String s1=t1.getText();
String s2=t2.getText();
int i=Integer.parseInt(s1);
int j=Integer.parseInt(s2);
String str=ae.getActionCommand();
if(str.equals("add"))
l4.setText(String.valueOf(i+j));
else if(str.equals("sub"))
l4.setText(String.valueOf(i-j));
else if(str.equals("mul"))
l4.setText(String.valueOf(i*j));
else if(str.equals("div"))
l4.setText(String.valueOf(i/j));
repaint();
}//actionPerformed() closed
public void paint(Graphics g)
{g.drawString("creator-amrendra",5,240);}
}

//create a html file in which "calculator.class" is tagged named as "cal.html".
/*(html) (head)
(applet code="calculator.class" height=250 width=300)
(/applet) (/head)(/html) */
//note :- use '>' & '<' instead of ')' & '(' respectively.
//run applet as "appletviewer cal.html"