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Java Discussion Thread
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Mar 24th, 2008

No action under action listener (ActionListener added!)

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I'm trying to show a dialog message if the user clicks a button and a text field is empty.

java Syntax (Toggle Plain Text)
Action listener -
 
        if(event.getSource() == cmdSaveSettings) 
        if(txtPlayerOneName.getText().equals(emptyText))        
        {
             JOptionPane.showMessageDialog(null, "alert", "Please enter player one's name",                                  JOptionPane.ERROR_MESSAGE);
        }
Action listener -

        if(event.getSource() == cmdSaveSettings) 
        if(txtPlayerOneName.getText().equals(emptyText))        
        {
             JOptionPane.showMessageDialog(null, "alert", "Please enter player one's name",                                  JOptionPane.ERROR_MESSAGE);
        }

Ive add an action to listener to the button and the textfield:
(mouse listener also as removes original text on click which works fine)

java Syntax (Toggle Plain Text)
        cmdSaveSettings = new JButton("Save Settings");
        this.cmdSaveSettings.addActionListener(this);
 
        txtPlayerOneName = new TextField("Player One", 15);
        this.txtPlayerOneName.addMouseListener(this);
        this.txtPlayerOneName.addActionListener(this);
        cmdSaveSettings = new JButton("Save Settings");
        this.cmdSaveSettings.addActionListener(this);

        txtPlayerOneName = new TextField("Player One", 15);
        this.txtPlayerOneName.addMouseListener(this);
        this.txtPlayerOneName.addActionListener(this);

Last edited by WolfPack; Mar 25th, 2008 at 11:22 am. Reason: corrected code tags.

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StephNicolaou

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Mar 24th, 2008

Re: No action under action listener (ActionListener added!)

It might help if you added brackets to the first if statement. (In red)

(Toggle Plain Text)

Action listener -

        if(event.getSource() == cmdSaveSettings) {
        if(txtPlayerOneName.getText().equals(emptyText))        
        {
             JOptionPane.showMessageDialog(null, "alert", "Please enter player one's name",                                  JOptionPane.ERROR_MESSAGE);
        }
}

Last edited by jasimp; Mar 24th, 2008 at 6:11 pm.

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Mar 24th, 2008

Re: No action under action listener (ActionListener added!)

No that's not it...

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Mar 24th, 2008

Re: No action under action listener (ActionListener added!)

I would put in some code at the top of the actionPerformed function that displays a message saying the program is inside actionPerformed. Or you can add a breakpoint and do the same thing. If it doesn't get inside the actionPerformed function, then the problem is not there. If it does, put some code to display that the event source is indeed cmdSaveSettings. If it isn't, again the problem is probably outside of actionPerformed. Then narrow it down some more to see if it gets in the code belonging to this if statement:

Java Syntax (Toggle Plain Text)
if(txtPlayerOneName.getText().equals(emptyText))
if(txtPlayerOneName.getText().equals(emptyText))

Last edited by VernonDozier; Mar 24th, 2008 at 7:19 pm.

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Mar 24th, 2008

Re: No action under action listener (ActionListener added!)

Sorry I don't understand, message saying program is inside ActionPerformed?

From what I got from that was

Java Syntax (Toggle Plain Text)
JOptionPane.showMessageDialog(add.ActionListener.this)
JOptionPane.showMessageDialog(add.ActionListener.this)

but thats not even the correct syntax...Sorry I'm new to this, could you explain in a bit more detail?

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Mar 24th, 2008

Re: No action under action listener (ActionListener added!)

Something like this:

JAVA Syntax (Toggle Plain Text)
public void actionPerformed(ActionEvent event)  
{
     System.out.println ("In actionPerformed");
     if(event.getSource() == cmdSaveSettings) 
     {
            System.out.println ("Source is cmdSaveSettings");
            if(txtPlayerOneName.getText().equals(emptyText))        
            {
                  System.out.println ("Inside if statement");
                  JOptionPane.showMessageDialog(null, "alert", "Please enter player one's name",  
                          JOptionPane.ERROR_MESSAGE);
            }
     }
}
public void actionPerformed(ActionEvent event)  
{
     System.out.println ("In actionPerformed");
     if(event.getSource() == cmdSaveSettings) 
     {
            System.out.println ("Source is cmdSaveSettings");
            if(txtPlayerOneName.getText().equals(emptyText))        
            {
                  System.out.println ("Inside if statement");
                  JOptionPane.showMessageDialog(null, "alert", "Please enter player one's name",  
                          JOptionPane.ERROR_MESSAGE);
            }
     }
}

Depending on which, if any, of these statements display as output when you press the button, you have a better handle on what is happening and what the problem is.

VernonDozier

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Mar 24th, 2008

Re: No action under action listener (ActionListener added!)

Thanks, I got source is cmdSaveSettings so that means theres something wrong with my second if statement?

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Mar 25th, 2008

Re: No action under action listener (ActionListener added!)

I've solved it, never mind! Thanks anyway - The empty text was set to null so I just changed null to "" and it worked. I wish the java website said that it made a difference!

StephNicolaou

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Mar 25th, 2008

Re: No action under action listener (ActionListener added!)

Well, equals compares the String values (the String equals method that is, of course) of the referenced Objects. The String value of the null reference is "null" not "". Keep that in mind. ;-)

Last edited by masijade; Mar 25th, 2008 at 9:52 am. Reason: Added parenthesised phrase

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