JAVA help

Profile · Posted 2006-04-09, 07:18 PM

I'm having some trouble in my java class at school. We are making a calculator program. I have the display and buttons and everything good. The only thing i need help on is getting the numbers up to the text field after i press the button. We arn't worrying about multiplication, addition or anything yet, so i dont think this will be too hard. The numbers just have to appear up in the text field. This is what i have so far.

Code:

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


public class Calculator extends Applet {

  private TextField screen;

  public void init () {
 
    this.setLayout(new GridLayout(3, 1, 3, 3));
    Panel A1 = new Panel();
    this.add(A1);
    Panel A2 = new Panel();
    this.add(A2);
    Panel A3 = new Panel();
    this.add(A3);
    A1.setLayout(new GridLayout(2, 1));
    screen = new TextField(12);
    A1.add(screen);
    Panel B1 = new Panel();
    B1.setLayout(new GridLayout(1, 4, 3, 3));
    B1.add(new Button("C"));
    B1.add(new Button("="));
    B1.add(new Button("/"));
    B1.add(new Button("*"));
    A1.add(B1);
    A2.setLayout(new GridLayout(2, 4, 3, 3));
    A2.add(new Button("7"));
    A2.add(new Button("8"));
    A2.add(new Button("9"));
    A2.add(new Button("C"));
    A2.add(new Button("4"));
    A2.add(new Button("5"));
    A2.add(new Button("6"));
    A2.add(new Button("+"));
    A3.setLayout(new GridLayout(1, 2, 3, 3));
    // 1, 2 and 0
    Panel B2 = new Panel();
    B2.setLayout(new GridLayout(2, 1, 3, 3));
    // 1 and 2
    Panel C1 = new Panel();
    C1.setLayout(new GridLayout(1, 2, 3, 3));
    C1.add(new Button("1"));
    C1.add(new Button("2"));
    B2.add(C1);
    B2.add(new Button("0"));
    // 3, . and =
    Panel B3 = new Panel();
    B3.setLayout(new GridLayout(1, 2, 3, 3));
    // 3 and .
    Panel C2 = new Panel();
    C2.setLayout(new GridLayout(2, 1, 3, 3));
    C2.add(new Button("3"));
    C2.add(new Button("."));
    B3.add(C2);
    B3.add(new Button("="));
    A3.add(B2);
    A3.add(B3);

  }

  public Insets getInsets() {
    return new Insets(5, 5, 5, 5);
  }

}

platnum · Posted 2006-04-09, 11:06 PM in reply to platnum's post "JAVA help"

To start out, you're going to need some sort of EventListener to acknowledge when you have cliked a button. I would set that up next.

Demosthenes

Ok, so I rethought the whole thing and this is what I came up with. Anyone see any problems?

Code:

import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;
public class CalculatorSUPER extends Applet implements ActionListener, KeyListener
{
final int MAX_INPUT_LENGTH = 17;
final int INPUT_MODE = 0;
final int RESULT_MODE = 1;
final int ERROR_MODE = 2;
int displayMode;
Label displayLabel;
boolean clearOnNextDigit;
double lastNumber;
char lastOperator;
public CalculatorSUPER()
	{
	super();
	setLayout (new BorderLayout());

	Panel buttonPanel = new Panel();

	Panel numberPanel = new Panel();
	numberPanel.setLayout(new GridLayout(4, 3));	

	addButtonToPanel (numberPanel, new Button("7"), Color.blue);
	addButtonToPanel (numberPanel, new Button("8"), Color.blue);
	addButtonToPanel (numberPanel, new Button("9"), Color.blue);
	addButtonToPanel (numberPanel, new Button("4"), Color.blue);
	addButtonToPanel (numberPanel, new Button("5"), Color.blue);
	addButtonToPanel (numberPanel, new Button("6"), Color.blue);
	addButtonToPanel (numberPanel, new Button("1"), Color.blue);
	addButtonToPanel (numberPanel, new Button("2"), Color.blue);
	addButtonToPanel (numberPanel, new Button("3"), Color.blue);
	addButtonToPanel (numberPanel, new Button("0"), Color.blue);


	buttonPanel.add(numberPanel);



	Panel controlPanel = new Panel();
	controlPanel.setLayout(new GridLayout(4, 1));	


	addButtonToPanel (controlPanel, new Button("C"), Color.cyan);


	buttonPanel.add(controlPanel);

	displayLabel = new Label("");
	displayLabel.setAlignment(Label.CENTER);
	add(displayLabel, "North");



	add(buttonPanel);
	addKeyListener(this);
	requestFocus();

	}
void setDisplayString(String s)
	{
	displayLabel.setText(s);
	}
String getDisplayString ()
	{
	return displayLabel.getText();
	}

void clearLastEntry()
	{
	setDisplayString("");
	clearOnNextDigit = true;
	displayMode = INPUT_MODE;
	}

void addButtonToPanel(Panel panel, Button button, Color backgroundColour)
	{
	panel.add(button);
	button.setBackground(backgroundColour);
	button.addKeyListener(this);
	button.addActionListener(this);
	}
public void actionPerformed (ActionEvent e)
	{
	processButton(e.getActionCommand());	
	}
void processButton(String command) 
	{
	if (command.equals("0")) addDigit(0);
	if (command.equals("1")) addDigit(1);
	if (command.equals("2")) addDigit(2);
	if (command.equals("3")) addDigit(3);
	if (command.equals("4")) addDigit(4);
	if (command.equals("5")) addDigit(5);
	if (command.equals("6")) addDigit(6);
	if (command.equals("7")) addDigit(7);
	if (command.equals("8")) addDigit(8);
	if (command.equals("9")) addDigit(9);

	if (command.equals("C")) clearLastEntry();
	}

void addDigit(int digit)
	{

	if (clearOnNextDigit)
		setDisplayString("");


	String inputString = getDisplayString();
	if ((!inputString.equals("0") || digit > 0)  && inputString.length() < MAX_INPUT_LENGTH)
		{
		setDisplayString(inputString + digit);
		}
	displayMode = INPUT_MODE;
	clearOnNextDigit = false;
	}
	

public void keyPressed(KeyEvent e)
	{
	}
public void keyReleased(KeyEvent e)
	{
	}
	
public void keyTyped(KeyEvent e)
	{
	String command;
	char keyChar = e.getKeyChar();
   if (keyChar == KeyEvent.VK_ESCAPE)
		{
		command = new String("C");
		}
	else
		{
		
		byte bytes[] = {(byte)keyChar};
		command = new String(bytes);
		}
	processButton(command);
	}
}

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