hi folks, im having a problem here on my code can't figure what's wrong..
so here's my code:
import java.awt.*;
import java.awt.Font.*;
import java.awt.Color.*;
import java.awt.Button.*;
import java.awt.event.*;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;
import javax.swing.*;
import javax.swing.JOptionPane;
public class Calc extends JFrame implements ActionListener
{
JTextArea txtArea;
static final String key1 = "789", key2 = "456", key3 = "123", key4 = "-*/";
int a = key1.length(), x, y, b = key2.length(), c = key3.length(), d = key4.length(), ctr = 0;
JButton button789[], button456[], button123[], buttonComm[];
String buffer = "", a1, a2, a3, a5;
char a4;
int total = 0;
JButton numLock, zero, dot, enter, plus, ast, min, div;
Calc()
{
setTitle("Bryan Mark's Calculator (c)");
setBackground(new Color(100,100,100));
setLayout(null);
add(txtArea = new JTextArea());
txtArea.setBounds(10, 10, 270, 50);
add(numLock = new JButton("A/C"));
numLock.setBounds(20,65,60,60);
numLock.addActionListener(this);
add(div = new JButton("/"));
div.setBounds(82, 65, 60, 60);
div.addActionListener(this);
add(ast = new JButton("*"));
ast.setBounds(144, 65, 60, 60);
ast.addActionListener(this);
add(min = new JButton("-"));
min.setBounds(206, 65, 60, 60);
min.addActionListener(this);
x = 20; y = 127;
button789 = new JButton[a];
for (int i = 0; i < a; i++)
{
button789[i] = new JButton( "" + key1.charAt(i) );
add(button789[i]);
button789[i].setBounds(x, y, 60, 60);
button789[i].addActionListener(this);
x = x + 62;
}
x = 20; y = 189;
button456 = new JButton[b];
for (int i = 0; i < b; i++)
{
button456[i] = new JButton( "" + key2.charAt(i) );
add(button456[i]);
button456[i].setBounds(x, y, 60, 60);
button456[i].addActionListener(this);
x = x + 62;
}
x = 20; y = 251;
button123 = new JButton[c];
for (int i = 0; i < c; i++)
{
button123[i] = new JButton( "" + key3.charAt(i) );
add(button123[i]);
button123[i].setBounds(x, y, 60, 60);
button123[i].addActionListener(this);
x = x + 62;
}
add(zero = new JButton("0"));
zero.setBounds(20,313,122,60);
zero.addActionListener(this);
add(dot = new JButton("."));
dot.setBounds(144,313,60,60);
dot.addActionListener(this);
add(plus = new JButton("+"));
plus.setBounds(206,127,60,122);
plus.addActionListener(this);
add(enter = new JButton("Enter"));
enter.setBounds(206,251,60,122);
enter.addActionListener(this);
setResizable(false);
resize(300,450);
show();
}
public void actionPerformed(ActionEvent e)
{
int a = key1.length(), x, y, b = key2.length(), c = key3.length(), d = key4.length();
if (e.getSource() == numLock)
{
txtArea.setText("");
ctr = 0;
}
else if (e.getSource() == plus)
{
ctr = 1;
txtArea.setText("");
}
else if (e.getSource() == min)
{
ctr = 2;
a1 = txtArea.getText();
txtArea.setText("");
}
else if (e.getSource() == ast)
{
ctr = 3;
a1 = txtArea.getText();
txtArea.setText("");
}
else if (e.getSource() == div)
{
ctr = 4;
a1 = txtArea.getText();
txtArea.setText("");
}
else if (e.getSource() == zero)
{
txtArea.append("0");
}
else if (e.getSource() == dot)
{
txtArea.append(".");
}
else if (e.getSource() == enter)
{
a2 = txtArea.getText();
if(ctr==1)
{
total = Integer.parseInt(a1)+Integer.parseInt(a2);
txtArea.setText(String.valueOf(total));
}
else if(ctr==2)
{
total=Integer.parseInt(a1)-Integer.parseInt(a2);
txtArea.setText(String.valueOf(total));
}
else if(ctr==3)
{
total=Integer.parseInt(a1)*Integer.parseInt(a2);
txtArea.setText(String.valueOf(total));
}
else
{
total=Integer.parseInt(a1)/Integer.parseInt(a2);
txtArea.setText(String.valueOf(total));
}
}
else
{
for (int i = 0; i < a; i++)
{
if (e.getSource() == button789[i])
{
a3 = txtArea.getText();
a4 = (char)key1.charAt(i);
a5 = a3 + a4;
txtArea.setText(a5);
}
}
for (int i = 0; i < b; i++)
{
if (e.getSource() == button456[i])
{
a3 = txtArea.getText();
a4 = (char)key2.charAt(i);
a5 = a3 + a4;
txtArea.setText(a5);
}
}
for (int i = 0; i < c; i++)
{
if (e.getSource() == button123[i])
{
a3 = txtArea.getText();
a4 = (char)key3.charAt(i);
a5 = a3 + a4;
txtArea.setText(a5);
}
}
}
}
public static void main(String[] args)
{
Calc c = new Calc();
c.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
here's my error:
Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: null
at java.lang.Integer.parseInt(Integer.java:454)
at java.lang.Integer.parseInt(Integer.java:527)
at Calc.actionPerformed(Calc.java:135)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
at java.awt.Component.processMouseEvent(Component.java:6505)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
at java.awt.Component.processEvent(Component.java:6270)
at java.awt.Container.processEvent(Container.java:2229)
at java.awt.Component.dispatchEventImpl(Component.java:4861)
at java.awt.Container.dispatchEventImpl(Container.java:2287)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
at java.awt.Container.dispatchEventImpl(Container.java:2273)
at java.awt.Window.dispatchEventImpl(Window.java:2719)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:729)
at java.awt.EventQueue.access$200(EventQueue.java:103)
at java.awt.EventQueue$3.run(EventQueue.java:688)
at java.awt.EventQueue$3.run(EventQueue.java:686)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
at java.awt.EventQueue$4.run(EventQueue.java:702)
at java.awt.EventQueue$4.run(EventQueue.java:700)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:699)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)
i post this cause i don't have an idea what my problem is.. the problem happens when i click enter for getting the result of the numbers that i click with the operation also i click..
