I need your comments , your suggestions , please.

Question

Use the necessary facilities of the Java Programming langgue to build a visual calculator which
can carry out tha following operation. The operation needed are :
+ - * / clear memorize recall
Each of these operations is represented by a button which a user can press in order to carry
out the task. This calculator can be used to work out the value of an expression such as :
23*12+22-3
Pressing a wrong commbination of keys may gererate a warning sound. Moreover an animated icon should
be used to indicate when "
- the calculator is idle and free to be used
- the calculator is busy ( being used )
***** This is the code :
import java.awt.event.*;//Abstract windows ToolKit
import java.awt.*;
public class calculator extends Frame implements ActionListener
TextField name;
Label aHeader;
Button b[];
String expression;
public calculator()
super("DUY 'S CALCULATOR");
setLayout(new BorderLayout());
Panel p1 = new Panel();
p1.setBackground(new Color(18,70,1));
p1.setLayout(new FlowLayout());
aHeader = new Label("DUY'S CALCULATOR");
aHeader.setFont(new Font("Times New Roman",Font.BOLD,24));
aHeader.setForeground(new Color(255,0,0));
p1.add(aHeader);
add("North",p1);
Panel p2 = new Panel();
p2.setBackground(new Color(27,183,100));
p2.setLayout(new GridLayout(0,1));
name = new TextField(20);
p2.add(name);
add("Center",p2);
Panel p3 = new Panel();
p3.setLayout(new GridLayout(0,6));
b = new Button[25];
b[0] = new Button("MC");
b[0].addActionListener(this);
b[1] = new Button("7");
b[1].addActionListener(this);
b[2] = new Button("8");
b[2].addActionListener(this);
b[3] = new Button("9");
b[3].addActionListener(this);
b[4] = new Button("/");
b[4].addActionListener(this);
b[5] = new Button("sqrt");
b[5].addActionListener(this);
b[6] = new Button("CE");
b[6].addActionListener(this);
b[7] = new Button("4");
b[7].addActionListener(this);
b[8] = new Button("5");
b[8].addActionListener(this);
b[9] = new Button("6");
b[9].addActionListener(this);
b[10] = new Button("*");
b[10].addActionListener(this);
b[11] = new Button("%");
b[11].addActionListener(this);
b[12] = new Button("MS");
b[12].addActionListener(this);
b[13] = new Button("1");
b[13].addActionListener(this);
b[14] = new Button("2");
b[14].addActionListener(this);
b[15] = new Button("3");
b[15].addActionListener(this);
b[16] = new Button("-");
b[16].addActionListener(this);
b[17] = new Button("1/x");
b[17].addActionListener(this);
b[18] = new Button("M+");
b[18].addActionListener(this);
b[19] = new Button("0");
b[19].addActionListener(this);
b[20] = new Button("+/-");
b[20].addActionListener(this);
b[21] = new Button(".");
b[21].addActionListener(this);
b[22] = new Button("+");
b[22].addActionListener(this);
b[23] = new Button("=");
b[23].addActionListener(this);
b[24] =new Button("exit");
b[24].addActionListener(this);
for(int i=0;i<=24;i++)
{ p3.add(b);
add("South",p3);
super.addWindowListener(new WindowAdapter(){
public void windowClosing(WindowEvent e)
{System.exit(0);}});
setLocation(200,100);
pack();
setVisible(true);
}//end of constructor
public void actionPerformed(ActionEvent evt)
String command = evt.getActionCommand();
StringBuffer tmp, first, second;
int value, size, k;
char ch, op = ' ';
first = new StringBuffer();
second = new StringBuffer();
if ("CE".equals(command))
name.setText("");
else if("7".equals(command))
expression = name.getText();
name.setText(expression+"7");
else if ("8".equals(command))
expression = name.getText();
name.setText(expression+"8");
else if ("9".equals(command))
expression = name.getText();
name.setText(expression+"9");
else if("4".equals(command))
expression = name.getText();
name.setText(expression+"4");
else if("5".equals(command))
expression = name.getText();
name.setText(expression+"5");
else if("6".equals(command))
expression = name.getText();
name.setText(expression+"6");
else if("1".equals(command))
expression = name.getText();
name.setText(expression+"1");
else if("2".equals(command))
expression = name.getText();
name.setText(expression+"2");
else if("3".equals(command))
expression = name.getText();
name.setText(expression+"3");
else if("0".equals(command))
expression = name.getText();
name.setText(expression+"0");
else if("+".equals(command))
expression = name.getText();
name.setText(expression+"+");
else if("-".equals(command))
expression = name.getText();
name.setText(expression+"-");
else if("*".equals(command))
expression = name.getText();
name.setText(expression+"*");
else if("/".equals(command))
expression = name.getText();
name.setText(expression+"/");
else if("=".equals(command))
expression = name.getText();
size = expression.length();
tmp = new StringBuffer( expression );
for(int i = 0;i<size;i++)
ch = tmp.charAt(i);
if(ch != '+' && ch != '*' && ch != '-' && ch != '/')
first . insert(i, ch);
else
op = ch;
k = 0;
for(int j = i+1; j< size ; j++)
ch = tmp.charAt(j);
second.insert(k,ch);
k++;
break;
switch(op)
case '+' : value = Integer.parseInt(new String(first)) +
Integer.parseInt(new String(second));
name.setText(new Integer(value).toString());
break;
case '-' : value = Integer.parseInt(new String(first)) -
Integer.parseInt(new String(second));
name.setText(new Integer(value).toString());
break;
case '*' : value = Integer.parseInt(new String(first)) *
Integer.parseInt(new String(second));
name.setText(new Integer(value).toString());
break;
case '/' : value = Integer.parseInt(new String(first)) /
Integer.parseInt(new String(second));
name.setText(new Integer(value).toString());
break;
} //end of actionPerformed
/**main method to invoke from JVM.*/
public static void main(String args[])
new calculator();
This is the file calculator.java .I create this program follow the lecturer's guide . But actually
i think this is not good jobs . Anybody can help me to change something on this program ???? . And
please show me the reason why in each case of its . Thanks so much .
I have to submit it by this friday, so i think i can receive all reply soon . Again, thanks so much.

Answer 1

As I said before, check out:
http://forum.java.sun.com/thread.jsp?forum=31&thread=271751
I actually think there's some examples of what NOT to do in that message that look uncannily similar to what you've posted.
This is the third time you've asked somebody to do your homework for you. Read the javadocs, check out the tutorials, test the code yourself and experiment with it.
You can't just throw a bunch of code out and ask some vague questions and expect answers.
This is the file calculator.java .I create this program follow the lecturer's guide . But actually
i think this is not good jobs . Anybody can help me to change something on this program ???? . And
please show me the reason why in each case of its . Thanks so much .
I have to submit it by this friday, so i think i can receive all reply soon . Again, thanks so much.
Start by asking some specific questions.
And your code would be much easier to read if you put it in [ code ] blocks. Check out http://forum.java.sun.com/faq.jsp#messageformat for information on formatting.