Correctly passing an element to a method

I am trying to change the color of a JPanel based on user input.

Currently my "submit" button's event handling code looks like this:

Code:

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private class SelectListener implements  ActionListener  {
               
                @Override
                public void actionPerformed(ActionEvent e) {
                        // TODO Auto-generated method stub
                        if (e.getSource() == "Submit"){
                               
                                action.ChangeColor(manager.getWords()[SelectWord.getSelectedIndex()],
                                                action.getColors()[SelectColor.getSelectedIndex()]);

                               
                        }
                       
                }
        }

}

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method change color looks like this:

Code:

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        public Word ChangeColor (Word word, Color color){
               
                word.getLabel().setForeground(color);
               
                return word;
        }

---

the word class is like this:

Code:

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package AlgorithmAnalyzer;

import java.awt.Color;
import java.awt.Font;

import javax.swing.JLabel;

public class Word {
       
        private JLabel wordLabel;
        private Color defaultColor = Color.BLACK;
        private String Name;
        private Font defaultFont = new Font("Serif",Font.BOLD,24);
       
       
        public Word (String text, WordManager manager) {
               
                Name = text;
                wordLabel = new JLabel(text);
                wordLabel.setFont(defaultFont);
                wordLabel.setForeground(defaultColor);
               
                manager.addWord(this);
               
        }
       
        public JLabel getLabel (){
               
                return wordLabel;
        }
       
        public String getName(){
                return Name;
        }
       
       

}

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Now, my logic here is that Im passing a word object to changeColor, which gets the words JPanel and changes its color. After that it returns a word (I'm not sure if this is required or not). When I run the program however nothing happens. I was guessing that Im passing either the wrong thing to my method or my method isn't changing the right thing, however trying to fix the problem assuming I was guessing correctly didnt help things. So I turn to the community :)

How do I get that color update to work?

Thanks in advance!

PS: I have been informed on a previous thread that my naming of classes,variables,methods,etc. is unorthodox, I have not yet gotten a chance to fix all the code to a standard java naming scheme.

Regarding

Code:

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public void actionPerformed(ActionEvent e) {
            // TODO Auto-generated method stub
            if (e.getSource() == "Submit"){

---

You shouldn't compare Strings with == but rather with the equals method.

But regardless of this, ActionEvent#getSource() returns the object that initiated the event, in this situation, the JButton, and certainly never a String.

ActionEvent#getActionCommand() on the other hand does return the actionCommand String, often the text of the button. If you do wish to test for this, though again use the equals method.

Thanks, the button works now :) I'm getting a null pointer but I already have that pinned down and know how to fix it :)

Quote:

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Originally Posted by aianta

Thanks, the button works now :) I'm getting a null pointer but I already have that pinned down and know how to fix it :)

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Good show, and good luck with the rest of the project!

So I fixed that null pointer that I was getting (was trying to access a color that didn't exist), now however I'm getting another null pointer and this one is stumping me. I'm calling getSelectedIndex and getting a null pointer when it uses the value to find an item off an array. I replaced the getSelectedIndex with the value it should have returned and found that to work fine.

Then I created a test variable and assigned the getSelectedIndex to it so I can check what value its returning. However, it turns out that it never returns a value at all. I checked my variable declarations and everything seemed fine there. Any ideas as to whats causing this error:

Code:

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Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
        at AlgorithmAnalyzer.GUI$SelectListener.actionPerformed(GUI.java:60)
        at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
        at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
        at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
        at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
        at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
        at java.awt.Component.processMouseEvent(Unknown Source)
        at javax.swing.JComponent.processMouseEvent(Unknown Source)
        at java.awt.Component.processEvent(Unknown Source)
        at java.awt.Container.processEvent(Unknown Source)
        at java.awt.Component.dispatchEventImpl(Unknown Source)
        at java.awt.Container.dispatchEventImpl(Unknown Source)
        at java.awt.Component.dispatchEvent(Unknown Source)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
        at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
        at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
        at java.awt.Container.dispatchEventImpl(Unknown Source)
        at java.awt.Window.dispatchEventImpl(Unknown Source)
        at java.awt.Component.dispatchEvent(Unknown Source)
        at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
        at java.awt.EventQueue.access$000(Unknown Source)
        at java.awt.EventQueue$1.run(Unknown Source)
        at java.awt.EventQueue$1.run(Unknown Source)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
        at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
        at java.awt.EventQueue$2.run(Unknown Source)
        at java.awt.EventQueue$2.run(Unknown Source)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
        at java.awt.EventQueue.dispatchEvent(Unknown Source)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
        at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
        at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
        at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
        at java.awt.EventDispatchThread.run(Unknown Source)

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heres all the gui.java code:

Code:

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import java.awt.BorderLayout;
import java.awt.FlowLayout;

import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;

public class GUI extends JFrame {
       
        private JComboBox SelectColor;
        private JComboBox SelectWord;
        private JButton Button;
        private WordManager manager;
       
        Actions action = new Actions();
       
        public GUI (WordManager manager){
               
                super ("test");
                this.setLayout(new FlowLayout());
               
                this.manager = manager;
               
                for (int i = 0; i < manager.getWords().length; i++){
                       
                        this.add(manager.getWords()[i].getLabel());
                }
               
                SelectListener handler = new SelectListener ();
               
                final JComboBox SelectWord = new JComboBox(manager.getWordNames());
                SelectWord.setSelectedIndex(0);
                SelectWord.addActionListener(handler);
                this.add(SelectWord);
               
               
                final JComboBox SelectColor = new JComboBox(action.getColorNames());
                SelectColor.setSelectedIndex(0);
                SelectColor.addActionListener(handler);
                this.add(SelectColor);
               
                JButton Button = new JButton ("Submit");
                Button.addActionListener(handler);
                this.add(Button);
                       
                }
       
       
        private class SelectListener implements  ActionListener  {
               
                @Override
                public void actionPerformed(ActionEvent e) {
                        // TODO Auto-generated method stub
                        if (e.getActionCommand() == "Submit"){
                               
                                int test = SelectWord.getSelectedIndex();
                               
                                System.out.println(test);
                               
                                action.ChangeColor(manager.getWords()[SelectWord.getSelectedIndex()],
                                                action.getColors()[SelectColor.getSelectedIndex()]);

                               
                        }
                       
                }
        }

}

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Any ideas :( ?