I coded a Java Swing component that shows a button twice when it is clicked. However, I only want the button to appear once when clicked. My code is below. Does anyone know what I am missing?
import java.awt.event.*;
public class checkIt2 implements ItemListener {
public void itemStateChanged(ItemEvent e) {
if(e.getStateChange() == ItemEvent.SELECTED) {
javax.swing.JOptionPane.showMessageDialog(null, "Check box 2 is selected");
JDBC_Demo6.check2.setSelected(true);
}
if (e.getStateChange() == ItemEvent.DESELECTED) {
JDBC_Demo6.check1.setSelected(false);
}
}
}
Here is the code in the JDBC_Demo6 class that pertains to the JCheckBox ItemListener class:
public class JDBC_Demo6 extends JFrame implements ActionListener {
public static JTextArea textArea;
static String critical_data;
private final static String newline = "\n";
public static JCheckBox check1;
public static JCheckBox check2;
public JDBC_Demo6(String s) {
super(s);
}
public void addComponentsToPane(final Container pane) {
textArea = new JTextArea(20, 75);
/* final JPanel compsToExperiment = new JPanel(new GridBagLayout()); */
// GridBagConstraint for button
/* This puts the buttons in the very center of the GUI */
//get Database data
JsonDB a = new JsonDB();
//store the output from the getDB method in this ArrayList collection
ArrayList<String> tmp = a.getDB();
//loop through the ArrayList and append each string to the text area
JScrollPane scrollPane = new JScrollPane();
//add a scrollpane to the GUI
//scrollPane.setSize(new Dimension(100, 100));
/* loop through the ArrayList with the results of the SQL query and then add them to the JPanel */
for(String s: tmp) {
textArea.append("From the database -> " + s + "\n");
}
scrollPane.setViewportView(textArea);
this.add(scrollPane);
scrollPane.updateUI();
/* add buttons */
JButton jB = new JButton("Send To ESB");
JButton jB2 = new JButton("Cancel");
jB.addActionListener(new goButton());
jB2.addActionListener(new cancelButton());
this.add(jB);
this.add(jB2);
/* check boxes */
check1 = new JCheckBox("Check Box 1");
check2 = new JCheckBox("Check Box 2");
check1.addItemListener(new checkIt());
check2.addItemListener(new checkIt2());
this.add(check1);
this.add(check2);
}
/**
* Create the GUI and show it. For thread safety,
* this method should be invoked from the
* event dispatch thread.
*/
private static void createAndShowGUI() {
//Create and set up the window.
JDBC_Demo6 frame = new JDBC_Demo6("JDBC Example #6");
frame.setSize(50, 50);
frame.setLayout(new FlowLayout());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Add contents to the window.
frame.addComponentsToPane(frame.getContentPane());
//Display the window.
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
//Schedule a job for the event dispatch thread:
//creating and showing this application's GUI.
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
public void actionPerformed(ActionEvent ae) {
}
} // end class
It is happening twice because the call JDBC_Demo6.check1.setSelected(true); triggers another call to ItemListener.itemStateChanged(). In this case it would be easier to use an ActionLister or a ChangeLister instead of an ItemListener, like in the code that follows. Although the call JDBC_Demo6.check1.setSelected(true); wont trigger another ActionListener.actionPerformed(), like it does for ItemListeners, the call is redundant and you should remove it.
Test this ActionListener to see if it works for you:
public class checkIt2 implements ActionListener {
@Override
public void actionPerformed(ActionEvent e) {
javax.swing.JOptionPane.showMessageDialog(null, "selected: " +
((JCheckBox)e.getSource()).isSelected());
}
}
And use this to register the listener:
check2.addActionListener(new checkIt2());