Reports

I'm new to Java Swing and I wasn't able to find much more information either on the internet. In my Netbeans project I also wanted to add a DocumentListener for some JTextFields in a JFrame.

I followed Dorian-Catalin's reply which was really helpful. The code allows to interact with the JText components overriding the 3 documentListener methods for the events.

jTextField1.getDocument().addDocumentListener(new DocumentListener() {
        @Override
        public void insertUpdate(DocumentEvent e) {
        }
        @Override
        public void removeUpdate(DocumentEvent e) {
        }
        @Override
        public void changedUpdate(DocumentEvent e) {
        }
    });

The issue was to insert this code into my NetBeans' source code for my JFrame.

Notice that I'm using the JFrame "Palette" menu provided by Netbeans in the Design Tab, which auto-generates the source code, which is not editable, so I couldn't insert this code manually in the editor (in the initComponent() block).

The only way I found in order to fit this code was to right-click the swing component (in my case a JTextField) and select "Customize Code...". Then pasting/writing the whole code.

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Going then to the Source Code editor, the first error I found was that DocumentListener should be imported:

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Despite the import, I still get an error, saying that the JFrame is not abstract and cannot override the methods. Following the suggestion "Implement all abstract methods", I eventually managed to make it work.

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Required by my learning course, I'm using Java 8 with Netbeans v.12. I'm not sure if in newer versions this has changed/fixed.

Before finding this solution I was struggling a bit. I could only find the document Property for the JTextField, but this seems not to do the job. In the Events tab, I couldn't find any Document related Event

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If I open the document Property with the 3dots button, in the tab I could only find the setDocument() method, in the "Custom code" section. The other options in the list didn't sound like the right ones, or I could not make them work either.

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Anyway, the only method proposed is "JTextField.setDocument()", which I couldn't make it usable for inserting the DocumentListener.

Hope this can help too

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