Difference between Applet and Frame?

Some differences are (summary from Lervik and Havdal: Java the UML Way, 2002, page 446):

An applet must be a public class, frame doesn't have to.

In an applet, construction happens in the init() method; in the frame, it's in the constructor.

The browser starts the applet. You start the frame from main() or another method.

Yes, given the source code of an applet, you can make the necessary changes to change it into a frame.

OleVVa at 2007-7-12 18:10:54 >

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

import java.lang.Math.*;

import java.math.BigInteger;

public class BigIntCalc extends JApplet implements ActionListener{

JLabel lN1, lN2;

JTextField tN1, tN2.

JButton btnAdd,btnSub,btnMul,btnDiv,btnClear; JTextArea outArea;

public void init(){

Box box=Box.createVerticalBox();

lN1=new JLabel("Write first number"); box.add(lN1);

tN1=new JTextField(100); tN1.setEditable(true); box.add(tN1);

lN2=new JLabel("write second number"); box.add(lN2);

tN2=new JTextField(100); tN2.setEditable(true); box.add(tN2);

btnAdd=new JButton("+"); btnAdd.addActionListener(this); box.add(btnAdd);

btnSub=new JButton("-"); btnSub.addActionListener(this); box.add(btnSub);

btnMul=new JButton("*"); btnMul.addActionListener(this); box.add(btnMul);

btnDiv=new JButton("/"); btnDiv.addActionListener(this); box.add(btnDiv);

btnClear=new JButton("Clear"); btnClear.addActionListener(this); box.add(btnClear);

String desc="This is a simple integer calculator\n";

outArea=new JTextArea(desc,30,60);

ScrollPane scrollPane=new ScrollPane();//.

scrollPane.add(outArea);

box.add(scrollPane);

Container c=getContentPane();

c.add(box);

setSize(600,300);

setVisible(true);

showStatus("Enter operands and operator");

}

public void actionPerformed(ActionEvent actionEvent){

if(actionEvent.getSource()==btnClear){

outArea.selectAll(); outArea.cut();

} else {

String sN1=tN1.getText(), sN2=tN2.getText(), sOp="";

if(sN1.equals("")){sN1="0"; showStatus("Enter first operation");} else

if(sN2.equals("")){sN2="0"; showStatus("Enter second operation");} else {

showStatus("Select operator or Clear");}

BigInteger bN1=new BigInteger(sN1);

BigInteger bN2=new BigInteger(sN2);

BigInteger bRes=BigInteger.ZERO, bResDiv[]={BigInteger.ZERO,BigInteger.ZERO};

BigInteger bRemainder=BigInteger.ZERO;

if(actionEvent.getSource()==btnAdd){bRes=bN1.add(bN2); sOp=" + ";}

if(actionEvent.getSource()==btnSub){bRes=bN1.subtract(bN2); sOp=" - ";}

if(actionEvent.getSource()==btnMul){bRes=bN1.multiply(bN2); sOp=" * ";}

if(actionEvent.getSource()==btnDiv){sOp=" / ";

if(bN2.signum()!=0)bResDiv=bN1.divideAndRemainder(bN2);

bRes=bResDiv[0]; bRemainder=bResDiv[1];

}

if(sOp.equals(" / ") && bN2.signum()==0){

showStatus("Cannot divide by zero");

} else {

outArea.append(bN1.toString() + sOp+bN2.toString() + " = " + bRes.toString() + "\n");

if(actionEvent.getSource()==btnDiv)outArea.append("Remainder = "+bRemainder.toString()+"\n");

showStatus("Calculations completed");

}

}

}

}

this is the main program ;

which steps i need to follow to make the change ?

Alenaa at 2007-7-12 18:10:54 >

Hmm, are you sure this was working?

Here's what I found:

- There's a typo in the line "JLabel lN1, lN2", it should end with a ";" instead of a dot

- Don't use heavy-weight components such as ScrollPane in a Swing UI; there's a Swing component called JScrollPane

- Method showStatus() does not exist

- Change "extends JApplet" to "extends JFrame"

- Change method init() to be the constructor

- Add a main method creating an instance of BigIntCalc

quittea at 2007-7-21 22:02:30 >

thx a lot...you are so kind....

one moe question .please.

how can i change the size of the button.if you run the program i receive the button are with different size .how can i make all with the same size.

thank you so much you really help me wnd now it works...

big thanks

Alenaa at 2007-7-21 22:02:30 >

Thank you so much.

i just want from you tow things?

1-how to change the button because i do not have the same button.i tryed what u told me but it does not work ?how to do it.

2-and the second thing is that i delete this method showstatus().and when i divide by zero i do not receive any thing.what i need to write in the place of it.

thank you

Alenaa at 2007-7-21 22:02:30 >