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Thread: Simple TextListener Problem =/ Please help!

  1. #1
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    Question Simple TextListener Problem =/ Please help!

    The goal of this program is pretty modest:

    There's a TextField, and a TextListener attached. So everytime the TextField is edited at all, textValueChanged(TextEvent e) method is triggered. This works fine.

    What I need to do, is every time the event is triggered, I need to compare the text in the TextField to a list of keywords. However, for some reason, if the text in the TextField is "a", (TextField.getText() == "a") returns false! Why!!!

    Here's my program, with an example of the issue:

    import java.awt.*;
    import java.awt.event.*;
     
    import javax.swing.*;
    import javax.swing.event.*;
    import javax.swing.text.*;
     
    import java.beans.PropertyChangeListener;
    import java.beans.PropertyChangeEvent;
     
    import java.text.*;
     
    public class FormattedTextFieldDemo extends JPanel
                                        implements TextListener {
     
        private TextField textField;
     
        public FormattedTextFieldDemo() {
            super(new BorderLayout());
     
            textField = new TextField(10);
            textField.addTextListener(this);
     
            JPanel labelPane = new JPanel(new FlowLayout());
            labelPane.add(textField);
     
            add(labelPane, BorderLayout.NORTH);
     
        }
     
        /**
         * THIS IS THE PROBLEM.
         **/
        public void textValueChanged(TextEvent e) {
     
            String currentText = textField.getText().toString();
     
            if (currentText == "a"  || currentText == "a ") {
                System.out.print("it's a!");
            } else {
                System.out.print("it's not a.");
            }
        }
     
        private static void createAndShowGUI() {
            JFrame frame = new JFrame("Austin's Program");
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     
            frame.add(new FormattedTextFieldDemo());
            frame.setSize(new Dimension(200,200));
            frame.setVisible(true);
        }
     
        public static void main(String[] args) {
            createAndShowGUI();
        }
    }


  2. #2
    Senile Half-Wit Freaky Chris's Avatar
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    Default Re: Simple TextListener Problem =/ Please help!

    Reading: Java: String Comparison

    Chris
    chris[at]javaprogrammingforums[dot]com

    Prifysgol Bangor University, North Wales

  3. The Following User Says Thank You to Freaky Chris For This Useful Post:

    austin.rose94 (December 8th, 2011)

  4. #3
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    Default Re: Simple TextListener Problem =/ Please help!

    It works! Thank you so much. I was wondering if it had something to do with deep vs shallow equality. Too new with Java to know much about it though.

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