Thread: Problem with Action Listener

Hi Guys,

Ok im developing a student record system to enter details etc but im having problems with my action listener recognising my buttons so i can define what method to call.

import javax.swing.*;   import java.awt.*; import java.awt.event.ActionEvent; import java.awt.event.ActionListener;   public class Gui extends JFrame implements ActionListener {	Store StudentStore = new Store(200);      	public static void main(String[] args)	{	JFrame frame = new JFrame("Test");	frame.setVisible(true);	frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);	frame.pack();	JPanel panel2 = new JPanel(new GridBagLayout());	frame.getContentPane().add(panel2, BorderLayout.NORTH);	GridBagConstraints d = new GridBagConstraints();  	}    	public Gui() {    	JFrame frame = new JFrame("Test");	frame.setSize(500,500);	frame.setVisible(true);	frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);  	JPanel panel2 = new JPanel(new GridBagLayout());	frame.getContentPane().add(panel2, BorderLayout.NORTH);	GridBagConstraints d = new GridBagConstraints();  	JLabel label1 = new JLabel("Please Enter Student Detailes Below");	d.gridx = 0;	d.gridy = 0;	d.insets = new Insets(5, 5, 5, 5);	panel2.add(label1, d);  	/*JPanel panel3 = new JPanel(new GridBagLayout());	frame.getContentPane().add(panel3, BorderLayout.CENTER);	GridBagConstraints b = new GridBagConstraints();*/  	/*JPanel panel4 = new JPanel(new GridBagLayout());	frame.getContentPane().add(panel4, BorderLayout.EAST);	GridBagConstraints h = new GridBagConstraints();*/    	JPanel panel1 = new JPanel(new GridBagLayout());	frame.getContentPane().add(panel1, BorderLayout.WEST);	GridBagConstraints c = new GridBagConstraints();	JLabel label2 = new JLabel("Enter Name:");	c.gridx = 0;	c.gridy = 0;	c.insets = new Insets(5, 5, 5, 5);	panel1.add(label2, c);  	JTextField eName = new JTextField(15);	c.gridx = 1;	c.gridy = 0;	c.insets = new Insets(5, 5, 5, 5);	panel1.add(eName);  	JLabel label3 = new JLabel("Select Gender:");	c.gridx = 0;	c.gridy = 1;	c.insets = new Insets(5, 5, 5, 5);	panel1.add(label3, c);  	JRadioButton maleButton = new JRadioButton("Male");	c.gridx = 1;	c.gridy = 1;	c.insets = new Insets(5, 5, 5, 5);	panel1.add(maleButton, c);  	JRadioButton fmaleButton = new JRadioButton("Female");	c.gridx = 2;	c.gridy = 1;	c.insets = new Insets(5, 5, 5, 5);	panel1.add(fmaleButton, c);  	JLabel label4 = new JLabel("Select Date of Birth:");	c.gridx = 0;	c.gridy = 2;	c.insets = new Insets(5, 5, 5, 5);	panel1.add(label4, c);    	JLabel label5 = new JLabel("Enter Email Address:");	c.gridx = 0;	c.gridy = 3;	c.insets = new Insets(5, 5, 5, 5);	panel1.add(label5, c);  	JTextField eMail = new JTextField(15);	c.gridx = 1;	c.gridy = 3;	c.insets = new Insets(5, 5, 5, 5);	panel1.add(eMail, c);  	JLabel label6 = new JLabel("Enter Student Number:");	c.gridx = 0;	c.gridy = 4;	c.insets = new Insets(5, 5, 5, 5);	panel1.add(label6, c);  	JTextField stuNum = new JTextField(15);	c.gridx = 1;	c.gridy = 4;	c.insets = new Insets(5, 5, 5, 5);	panel1.add(stuNum, c);  	JLabel label7 = new JLabel("Select Enrolment Date:");	c.gridx = 0;	c.gridy = 5;	c.insets = new Insets(5, 5, 5, 5);	panel1.add(label7, c);  	JLabel label8 = new JLabel("Enter Course Name:");	c.gridx = 0;	c.gridy = 6;	c.insets = new Insets(5, 5, 5, 5);	panel1.add(label8, c);  	JTextField courseName = new JTextField(15);	c.gridx = 1;	c.gridy = 6;	c.insets = new Insets(5, 5, 5, 5);	panel1.add(courseName, c);  	JLabel label9 = new JLabel("Enter Year/Level:");	c.gridx = 0;	c.gridy = 7;	c.insets = new Insets(5, 5, 5, 5);	panel1.add(label9, c);  	JTextField eYear = new JTextField(15);	c.gridx = 1;	c.gridy = 7;	c.insets = new Insets(5, 5, 5, 5);	panel1.add(eYear, c);    	String[] dateString = {"1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "20", "21", "22", "23", "24", "25", "26", "27", "28", "29", "30", "31" };	String[] monthString = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December" };	String[] yearString = {"1970", "1971", "1972", "1973","1974", "1975", "1976", "1977", "1978", "1979", "1980","1981", "1982", "1983","1984", "1985", "1986", "1987", "1988", "1989", "1990", "1991", "1992", "1993","1994", "1995", "1996", "1997", "1998", "1999", "2000", "2001", "2002", "2003", "2004", "2005","2006","2007","2008","2009", "2010", "2011", "2012" };	JComboBox dateList = new JComboBox(dateString);	c.gridx = 1;	c.gridy = 2;	panel1.add(dateList, c);	JComboBox monthList = new JComboBox(monthString);	c.gridx = 2;	c.gridy = 2;	panel1.add(monthList, c);	JComboBox yearList = new JComboBox(yearString);	c.gridx = 3;	c.gridy = 2;	panel1.add(yearList, c);  	String[] dateEString = {"1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "20", "21", "22", "23", "24", "25", "26", "27", "28", "29", "30", "31" };	String[] monthEString = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December" };	String[] yearEString = {"1970", "1971", "1972", "1973","1974", "1975", "1976", "1977", "1978", "1979", "1980","1981", "1982", "1983","1984", "1985", "1986", "1987", "1988", "1989", "1990", "1991", "1992", "1993","1994", "1995", "1996", "1997", "1998", "1999", "2000", "2001", "2002", "2003", "2004", "2005","2006","2007","2008","2009", "2010", "2011", "2012" };	JComboBox dateEList = new JComboBox(dateEString);	c.gridx = 1;	c.gridy = 5;	panel1.add(dateEList, c);	JComboBox monthEList = new JComboBox(monthEString);	c.gridx = 2;	c.gridy = 5;	panel1.add(monthEList, c);	JComboBox yearEList = new JComboBox(yearEString);	c.gridx = 3;	c.gridy = 5;	panel1.add(yearEList, c);        	JButton enter = new JButton("Enter");	c.gridx = 1;	c.gridy = 8;	c.insets = new Insets(5, 5, 5, 5);	enter.addActionListener(this);	panel1.add(enter, c);    	JButton wipe = new JButton("Clear");	wipe.addActionListener(this);	c.gridx = 2;	c.gridy = 8;	c.insets = new Insets(5, 5, 5, 5);	panel1.add(wipe, c);      	JMenuBar menubar = new JMenuBar();	frame.setJMenuBar(menubar);  	JMenu file = new JMenu("File");	menubar.add(file);	JMenuItem New = new JMenuItem("New");	JMenuItem save = new JMenuItem("Save");	JMenuItem open = new JMenuItem("Open");	file.add(New);	file.add(save);	file.add(open);  	JMenu record = new JMenu("Record");	menubar.add(record);	JMenuItem add = new JMenuItem("Add");	JMenuItem display = new JMenuItem("Display");	JMenuItem clear = new JMenuItem("Clear");	record.add(add);	record.add(display);	record.add(clear);      	}  	public void actionPerformed(ActionEvent e) {	if (e.getSource() == wipe)	{	addStudent();	}  	if (e.getSource() == enter){    	} } }

Any help gettin the action listener to work and placing the method in the appropriate place would be greatly appreciated.

Your JButtons are declared in the scope of the Gui() method [bad choice of method name, should start with a lowercase letter] so cannot be accessed from another method. To be able to access them in the actionPerformed(...) method, declare them as instance fields.

You need to brush up on basics before going any further, this has nothing to do with GUI programming. Recommended reading:
The Java™ Tutorials

When you master the basics, you might prefer to give each button its own ActionListener in the form of an anonymous inner class. 'Switchboard' type class-level actionPerformed(...) methods quickly grow cumbersome and unwieldy.

db

To extend from Darryl's advice, another option you may wish to take advantage of is the action command of the ActionEvent

public void actionPerformed(ActionEvent e){ String command = e.getActionCommand(); if ( "Clear".equals(command)){ //clear }else if{   } }

Its ok guys thanks for help but i sorted it anyway, the file is not actually called GUI its called controller i just put gui in there as that was my test class. I just needed to initialize the buttons before the method.

To be more exact, you needed to declare the buttons in the class scope.

db