Thread: Need help building a simple calculator

I am trying to get the number keys right now to post there number in the tf text field.
Right now I am getting a few errors and noting happens when you click one the buttons.

here my code

import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
 
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.JTextField;
 
 
 
 
public class BasicGUI extends JFrame implements ActionListener {
 
	private JButton b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, plus, equal;
	private JTextField tf;
	private JPanel display, keypad;
	private GridLayout bGrid;
 
	private class MyListener implements ActionListener {
		public void actionPerformed(ActionEvent e){
			JButton b = (JButton)e.getSource();
 
			String output = "";
 
			if (b == b0){
				output += "0";
			} else if (b == b1){
				output += "1";
			} else if (b == b2){
				output += "2";
			} else if (b == b3){
				output += "3";
			} else if (b == b4){
				output += "4";
			}else if (b == b5){
				output += "5";
			}else if (b == b6){
				output += "6";
			}else if (b == b7){
				output += "7";
			}else if (b == b8){
				output += "8";
			}else if (b == b9){
				output += "9";
			}
 
			//tarea.setText(out);
			tf.setText(output);
 
 
		}
	}
 
 
	public BasicGUI() {
 
		super("My First GUI Application");
 
		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 
 
		bGrid = new GridLayout(4, 3, 2, 2);
 
		keypad = new JPanel(bGrid);
		display = new JPanel();
 
		b0 = new JButton("0");
		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");
		plus = new JButton("+");
		equal = new JButton("=");
 
		keypad.add(b0);
		keypad.add(b1);
		keypad.add(b2);
		keypad.add(b3);
		keypad.add(b4);
		keypad.add(b5);
		keypad.add(b6);
		keypad.add(b7);
		keypad.add(b8);
		keypad.add(b9);
		keypad.add(plus);
		keypad.add(equal);
 
 
		tf = new JTextField(20);
		display.add(tf);
 
 
 
 
		this.add(display, BorderLayout.NORTH);
		this.add(keypad, BorderLayout.SOUTH);
 
 
		this.pack();
 
 
	}
	/**
	 * @param args
	 */
	public static void main(String[] args) {
 
		new BasicGUI().setVisible(true);
 
	}
	@Override
	public void actionPerformed(ActionEvent arg0) {
		// TODO Auto-generated method stub
 
	}
 
}

Thank you for any help you can give.

errors are fixed, but I am having problems register my buttons to post to the tf text field when you click on them.

I just improved my code, new code posted below

import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
 
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.JTextField;
 
public class BasicGUI extends JFrame implements ActionListener {
 
	private JButton b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, plus, equal;
	private JTextField tf;
	private JPanel display, keypad;
	private GridLayout bGrid;
	String outputTf = "";
	int output = 0;
	String n = "";
	String i = "";
	int num = 0;
 
 
	public void actionPerformed(ActionEvent e) { // event handler
		JButton b = (JButton) e.getSource();
 
		if (b == b0) {
			i = Integer.toString(0);
			n = n +  Integer.toString(0);
 
		} else if (b == b1) {
			i = Integer.toString(1);
			n = n +  Integer.toString(1);
 
		} else if (b == b2) {
			i = Integer.toString(2);
			n = n +  Integer.toString(2);
 
		} else if (b == b3) {
			i = Integer.toString(3);
			n = n +  Integer.toString(3);
 
		} else if (b == b4) {
			i = Integer.toString(4);
			n = n +  Integer.toString(4);
 
		} else if (b == b5) {
			i = Integer.toString(5);
			n = n +  Integer.toString(5);
 
		} else if (b == b6) {
			i = Integer.toString(6);
			n = n +  Integer.toString(6);
 
		} else if (b == b7) {
			i = Integer.toString(7);
			n = n +  Integer.toString(7);
 
		} else if (b == b8) {
			i = Integer.toString(8);
			n = n +  Integer.toString(8);
 
		} else if (b == b9) {
			i = Integer.toString(9);
			n = n +  Integer.toString(9);
 
		} else if (b == plus) {
			num = num + Integer.parseInt(n);
			n="";
			i = "+";
 
 
		} else if (b == equal) {
			output = num + Integer.parseInt(n);
			i = "="+ output;
		}
 
		outputTf = outputTf + i;
		tf.setText(outputTf);
	}
 
	public BasicGUI() {
 
		super("My First GUI Application");
 
		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 
		bGrid = new GridLayout(4, 3, 2, 2);
 
		keypad = new JPanel(bGrid);
		display = new JPanel();
 
		b0 = new JButton("0");
		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");
		plus = new JButton("+");
		equal = new JButton("=");
 
		keypad.add(b0);
		keypad.add(b1);
		keypad.add(b2);
		keypad.add(b3);
		keypad.add(b4);
		keypad.add(b5);
		keypad.add(b6);
		keypad.add(b7);
		keypad.add(b8);
		keypad.add(b9);
		keypad.add(plus);
		keypad.add(equal);
 
		tf = new JTextField(20);
		display.add(tf);
 
		this.add(display, BorderLayout.NORTH);
		this.add(keypad, BorderLayout.SOUTH);
		this.pack();
 
		// register the event listener with the buttons
 
		b0.addActionListener(this);
		b1.addActionListener(this);
		b2.addActionListener(this);
		b3.addActionListener(this);
		b4.addActionListener(this);
		b5.addActionListener(this);
		b6.addActionListener(this);
		b7.addActionListener(this);
		b8.addActionListener(this);
		b9.addActionListener(this);
		plus.addActionListener(this);
		equal.addActionListener(this);
	}
 
	/**
	 * @param args
	 */
	public static void main(String[] args) {
 
		new BasicGUI().setVisible(true);
	}
}