calculator applet

[davidmccabe]

hi,

i have been asked to create a calculator applet which includes basic functions (i.e add, subtract, multiply, divide)
But aswell square root, recipricol, positive/negative number switch.

It also has to be able to save the contents of a display field to a memory location, retrieve this data and clear the memory.

The code below is what i have managed so far, but i have no clue about the rest of the functions that are to be included i.e.sqrt etc.

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

public class Calculator extends Applet implements
ActionListener
{ 	
        Label displayLabel, enterLabel;
	TextField displayBox, enterBox;
	Button addButton, subtButton, multButton, divButton;
	Button clearButton, exitButton;
	
	Button sqrButton;
	
	double display_total, new_value;
	String displayString, inputString;
	
	public void init()
	{ 	displayLabel = new Label("Display");
		displayBox = new TextField(12);
		add(displayLabel);
		add(displayBox);
		displayBox.setEditable(false);
		display_total = 0.0;
		displayString = Double.toString(display_total);
		displayBox.setText(displayString);
		
		enterLabel = Label("Enter");
		enterBox = new TextField(12);
		add(enterLabel);
		add(enterBox);
		
		addButton = new Button("+");
		add(addButton);
		addButton.addActionListener(this);

		subtButton = new Button("-");
		add(subtButton);
		subtButton.addActionListener(this);
		
		multButton = new Button("*");
		add(multButton);
		multButton.addActionListener(this);

		divButton = new Button("/");
		add(divButton);
		divButton.addActionListener(this);

		clearButton = new Button("Clear");
		add(clearButton);
		clearButton.addActionListener(this);

		exitButton = new Button("Exit");
		add(exitButton);
		exitButton.addActionListener(this);
		
} end init

public void actionPerformed(ActionEvent event)
{	 	
if	(arg.equals("Exit"))
// Exit button clicked
	{ 	Graphics g = this.getGraphics();
		g.dispose();
		System.exit(0);
	}	//exit
else if (arg.equals("Clear"))
// Clear button clicked
	{ 	display_total = 0.0;
		displayString = Double.toString(display_total);
		displayBox.setText(displayString);
	} 	//clear
	
else
{ 	try
	{ inputString = enterBox.getText();
	new_value =	Double.valueOf(inputString).doubleValue();
	showStatus("");
	if(arg.equals("+"))
		display_total = display_total + new_value;
	else if (arg.equals("-"))
		display_total = display_total - new_value;
	else if (arg.equals("*"))
		display_total = display_total * new_value;
	else if (arg.equals("/"))
		display_total = display_total / new_value;
	
	else if (arg.equals("sqr"))
		display_total = display_total * display_total;
		
}//try
catch (NumberFormatException entry)
{ 	showStatus("Error: Invalid Input");
	enterBox.setText("");
}//catch

}//else
}//ActionPerformed
}//Calculator

ANY help apreciated.

Thanks

[Drift]

} end init

public void actionPerformed(ActionEvent event)

in line 58 there was an error,how can ı solve that?compiler says ";" expected but it doesn't work.Could you help me?

[Belisarius]

You need to comment out "end init". Java is interpreting this as a statement, which is why it's complaining about the lack of ";"

[Drift]

belisarius;
Could you explain your answer,can we solve that problem?

[Belisarius]

} end init

The "}" ends a statement in Java. It now begins processing the next statement, which happens to be "end init". This is obviously a comment that wasn't actually commented out. It's a syntatical error - Java tries to interpret it as best as it can, but because it doesn't make any sense it throws back it's best guess as to what is wrong with it - that is, the statement "end init" is lacking an ending semi-colon.

To resolve the error, simply comment out "end init".