Passing a field in a button to the actionPerformed()

Question

I have a series of buttons in a JApplet.
For an example I define a button in init() by:
ButtonArray[ i ] = new MyButton( "Clear", CLEAR, 0 );
ButttonArray[ i ].addActionListener( this );
Then in the actionPerformed() there is an if statement, which, depending on
the type of button, calls one of two methods. The methods require a specific field value ( one needs the 2nd field value,
the other needs the 3rd field value ).
Such as ( the astericks is where the problem is ):
if ( evt.getActionCommand().equals( "NO_OP" ) ){
evaluate( ** needs 3rd value ** );
} else {
doCalc( ** needs 2nd value ** );
I've been stumped for hours on this so any help is greatly appreciated.
Thanks

Answer 1

Here it is. I posted all of it. I know there are easier ways to do create
this type of app, but I need to know for future GUI projects.
custom button class first then the applet code.
public class HandyButton extends javax.swing.JButton {
/** for function button */
private int operation;
/** for number button */
private int value;
/** Creates HandyButton */
public HandyButton( String buttonText,int nOp,int nValue ) {
super( buttonText );
operation = nOp;
value = nValue;
public int getOp() { return operation; }
public int getValue() { return value; }
Here is the applet code:
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import javax.swing.event.*;
//** Be sure to have HandyButton.java AND HandyFrame.java before compiling. */
public class HandyCalc extends javax.swing.JApplet implements ActionListener {
/** Button operation constants */
public final int NO_OP = 0;
public final int ADD = 1;
public final int SUBTRACT = 2;
public final int MULTIPLY = 3;
public final int DIVIDE = 4;
public final int POSNEG = 5;
public final int SQRT = 6;
public final int EQUALS = 7;
public final int CLEAR = 8;
public final int SIN = 9;
public final int COS = 10;
public final int TAN = 11;
public final int DECIMAL = -1;
/** GUI component declaration */
/** Text field object */
private javax.swing.JTextField output;
/** Panel for number keypad */
private javax.swing.JPanel pnlNumbers;
/** Buttons for number keypad */
private HandyButton btnNumbers[];
/** Operation buttons */
private HandyButton btnFunctions[ ];
private HandyButton btnArrayHButtons[ ];
private int buttonCount;
/** Panel for operation buttons */
private javax.swing.JPanel pnlFunctions;
/** Display string */
String sDisplay;
/** Operation to do */
int nOp = NO_OP;
/** Number is a new number */
boolean bNewNum = true;
/** Number is a decimal */
boolean bIsDecimal = false;
public void init() {
/** Set HandyButton arrays */
btnFunctions = new HandyButton[ 9 ];
btnNumbers = new HandyButton[ 12 ];
//buttonCount = 21
btnArrayHButtons = new HandyButton[ buttonCount ];
//getContentPane().setName("pnlGod");
/** Create Text field */
JTextField output = new JTextField();
output.setAlignmentY(50.0F);
output.setAlignmentX(20.0F);
output.setPreferredSize(new java.awt.Dimension(60, 30));
output.setMaximumSize(new java.awt.Dimension(60, 30));
output.setMargin(new java.awt.Insets(2, 2, 2, 2));
output.setMinimumSize(new java.awt.Dimension(50, 30));
output.setBorder(new javax.swing.border.MatteBorder( 1, 3, 3, 1, new java.awt.Color ( 51, 0, 102 ) ) );
output.setFont(new Font("Helvetica", Font.BOLD, 18));
output.setText("0");
//output.setBackground(new java.awt.Color ( 204, 255, 255 ));
output.setHorizontalAlignment( javax.swing.SwingConstants.RIGHT );
/** Add text field to frame */
getContentPane().add( output, java.awt.BorderLayout.NORTH );
/** Create function panel */
JPanel pnlFunctions = new JPanel();
pnlFunctions.setLayout( new java.awt.GridLayout( 5, 2, 2, 2 ) );
/** Create function buttons */
//HandyButton btnAdd = new HandyButton( "+", ADD, 0 );
btnFunctions[ 0 ] = new HandyButton( "+", ADD, 0 );
btnFunctions[ 0 ].setActionCommand( "ADD" );
pnlFunctions.add( btnFunctions[ 0 ] );
//HandyButton btnSin = new HandyButton( "Sin", SIN, 0 );
btnFunctions[ 1 ] = new HandyButton( "Sin", SIN, 0 );
btnFunctions[ 1 ].setActionCommand( "SIN" );
pnlFunctions.add( btnFunctions[ 1 ] );
//HandyButton btnSubt = new HandyButton( "-", SUBTRACT, 0 );
btnFunctions[ 2 ] = new HandyButton( "-", SUBTRACT, 0 );
btnFunctions[ 2 ].setActionCommand( "SUBTRACT" );
pnlFunctions.add( btnFunctions[ 2 ] );
//HandyButton btnCos = new HandyButton( "Cos", COS, 0 );
btnFunctions[ 3 ] = new HandyButton( "Cos", COS, 0 );
btnFunctions[ 3 ].setActionCommand( "COS" );
pnlFunctions.add( btnFunctions[ 3 ] );
//HandyButton btnMult = new HandyButton( "*", MULTIPLY, 0 );
btnFunctions[ 4 ] = new HandyButton( "*", MULTIPLY, 0 );
btnFunctions[ 4 ].setActionCommand( "MULTIPLY" );
pnlFunctions.add( btnFunctions[ 4 ] );
//HandyButton btnTan = new HandyButton( "Tan", TAN, 0 );
btnFunctions[ 5 ] = new HandyButton( "Tan", TAN, 0 );
btnFunctions[ 5 ].setActionCommand( "TAN" );
pnlFunctions.add( btnFunctions[ 5 ] );
//HandyButton btnDiv = new HandyButton( "�", DIVIDE, 0 );
btnFunctions[ 6 ] = new HandyButton( "�", DIVIDE, 0 );
btnFunctions[ 6 ].setActionCommand( "DIVIDE" );
pnlFunctions.add( btnFunctions[ 6 ] );
//HandyButton btnClear = new HandyButton( "Clear", CLEAR, 0 );
btnFunctions[ 7 ] = new HandyButton( "Clear", CLEAR, 0 );
btnFunctions[ 7 ].setActionCommand( "CLEAR" );
pnlFunctions.add( btnFunctions[ 7 ] );
//HandyButton btnEquals = new HandyButton( "=", EQUALS, 0 );
btnFunctions[ 8 ] = new HandyButton( "=", EQUALS, 0 );
btnFunctions[ 8 ].setActionCommand( "EQUALS" );
pnlFunctions.add( btnFunctions[ 8 ] );
for ( int i = 0; i < btnFunctions.length; i++ ) {           
btnFunctions[ i ].addActionListener( this );
/** Add functions panel to frame */
getContentPane().add( pnlFunctions, java.awt.BorderLayout.EAST );
/** Create number panel */
JPanel pnlNumbers = new JPanel();
pnlNumbers.setLayout( new java.awt.GridLayout( 4, 3, 2, 2 ) );
/** Create number buttons */
//HandyButton btnNum1 = new HandyButton( "1", NO_OP, 1 );
btnNumbers[ 0 ] = new HandyButton( "1", NO_OP, 1 );
btnNumbers[ 0 ].setActionCommand( "NO_OP" );
pnlNumbers.add( btnNumbers[ 0 ] );
//HandyButton btnNum2 = new HandyButton( "2", NO_OP, 2 );
btnNumbers[ 1 ] = new HandyButton( "2", NO_OP, 2 );
btnNumbers[ 1 ].setActionCommand( "NO_OP" );
pnlNumbers.add( btnNumbers[ 1 ] );
//HandyButton btnNum3 = new HandyButton( "3", NO_OP, 3 );
btnNumbers[ 2 ] = new HandyButton( "3", NO_OP, 3 );
btnNumbers[ 2 ].setActionCommand( "NO_OP" );
pnlNumbers.add( btnNumbers[ 2 ] );
//HandyButton btnNum4 = new HandyButton( "4", NO_OP, 4 );
btnNumbers[ 3 ] = new HandyButton( "4", NO_OP, 4 );
btnNumbers[ 3 ].setActionCommand( "NO_OP" );
pnlNumbers.add( btnNumbers[ 3 ] );
//HandyButton btnNum5 = new HandyButton( "5", NO_OP, 5 );
btnNumbers[ 4 ] = new HandyButton( "5", NO_OP, 5 );
btnNumbers[ 4 ].setActionCommand( "NO_OP" );
pnlNumbers.add( btnNumbers[ 4 ] );
//HandyButton btnNum6 = new HandyButton( "6", NO_OP, 6 );
btnNumbers[ 5 ] = new HandyButton( "6", NO_OP, 6 );
btnNumbers[ 5 ].setActionCommand( "NO_OP" );
pnlNumbers.add( btnNumbers[ 5 ] );
//HandyButton btnNum7 = new HandyButton( "7", NO_OP, 7 );
btnNumbers[ 6 ] = new HandyButton( "7", NO_OP, 7 );
btnNumbers[ 6 ].setActionCommand( "NO_OP" );
pnlNumbers.add( btnNumbers[ 6 ] );
//HandyButton btnNum8 = new HandyButton( "8", NO_OP, 8 );
btnNumbers[ 7 ] = new HandyButton( "8", NO_OP, 8 );
btnNumbers[ 7 ].setActionCommand( "NO_OP" );
pnlNumbers.add( btnNumbers[ 7 ] );
//HandyButton btnNum9 = new HandyButton( "9", NO_OP, 9 );
btnNumbers[ 8 ] = new HandyButton( "9", NO_OP, 9 );
btnNumbers[ 8 ].setActionCommand( "NO_OP" );
pnlNumbers.add( btnNumbers[ 8 ] );
//HandyButton btnPosNeg = new HandyButton( "+/-", NO_OP, 0 );
btnNumbers[ 9 ] = new HandyButton( "+/-", NO_OP, 0 );
btnNumbers[ 9 ].setActionCommand( "NO_OP" );
pnlNumbers.add( btnNumbers[ 9 ] );
//HandyButton btnNum0 = new HandyButton( "0", NO_OP, 0 );
btnNumbers[ 10 ] = new HandyButton( "0", NO_OP, 0 );
btnNumbers[ 10 ].setActionCommand( "NO_OP" );
pnlNumbers.add( btnNumbers[ 10 ] );
//HandyButton btnDecimal = new HandyButton( ".", NO_OP, DECIMAL );
btnNumbers[ 11 ] = new HandyButton( ".", NO_OP, DECIMAL );
btnNumbers[ 11 ].setActionCommand( "NO_OP" );
pnlNumbers.add( btnNumbers[ 11 ] );
for ( int i = 0; i < btnNumbers.length; i++ ) {
btnNumbers[ i ].addActionListener( this );
/** Add numbers panel to frame */
getContentPane().add( pnlNumbers, java.awt.BorderLayout.CENTER );
String sTenth = (new Double(0.1)).toString();
sDisplay = sTenth.substring(sTenth.length()-2).substring(0, 1);
public void actionPerformed( java.awt.event.ActionEvent evt ) {               
Object temp = evt.getSource();
JOptionPane.showMessageDialog( null, String.valueOf(evt. ) );
//int buttonCount = btnNumbers.length + btnFunctions.length;
//int allButtons;
try {
JOptionPane.showMessageDialog( null, String.valueOf(temp.getClass().getDeclaredField( "value").getInt( "value" ) ) );
catch ( NoSuchFieldException e1 ) {
JOptionPane.showMessageDialog( null, e1 );
catch ( IllegalAccessException e2 ) {
JOptionPane.showMessageDialog( null, e2 );
JOptionPane.showMessageDialog( null, "You clicked a button\n" + evt.getActionCommand() );
buttonCount = btnFunctions.length + btnNumbers.length;
/** Determine what type of button - function or number */
JOptionPane.showMessageDialog( null, evt.getSource() );
if ( evt.getActionCommand().equals( "NO_OP" ) ){
JOptionPane.showMessageDialog( null, "number key\n" );
evaluate( evt.getSource( nValue ) );
} else {
JOptionPane.showMessageDialog( null, "function key" );
doCalc( evt.getSource() );
public void evaluate( int nValue ) {
JOptionPane.showMessageDialog( null, "Starting method evaluate\nButton value: " + nValue );
String Number;
if(nValue == DECIMAL)
if(!bIsDecimal)
if(bNewNum)
output.setText("0");
bNewNum = false;
bIsDecimal = true;
Number = sDisplay;
else
return;
else
Number = (new Integer(nValue)).toString();
if(bNewNum)
output.setText(Number);
if(nValue != 0)
bNewNum = false;
else
output.setText(output.getText() + Number);
repaint();
public void doCalc( int nOp ) {
JOptionPane.showMessageDialog( null, "Made it to doCalc\n" );
public static void main(String args[]) {
/** Create a handy frame */
HandyFrame hfrmMain = new HandyFrame( "Handy Calculator V1.0" );
/** Create a handy calculator */
HandyCalc HCalc = new HandyCalc();
/** Build the handy calculator */
HCalc.init();
/** Put handy calculator on the frame */
hfrmMain.getContentPane().add( "Center", HCalc );
/** Package the frame */
hfrmMain.pack();
/** Display the frame */
hfrmMain.show();