How to input integer number in Swing?

Question

I have code

    NumberFormat format = NumberFormat.getIntegerInstance();
    format.setGroupingUsed(false);

    JFormattedTextField jtf = new JFormattedTextField(format);

    jtf.setValue(new Integer(0));
    jtf.setColumns(10);

but when I input characters in text field they stay printed until i switch to another text field. I need to forbid characters input totally, i mean when character is inputted i need to delete at the moment or make somehow for character to not even appear for processing by listener if that is possible and also not to appear in text field ofcourse. I mean only characters which are digits must appear.

Why are you defining a second `JFormattedTextField` called `jtf` there? — Tripp Kinetics, Nov 20 '15 at 15:51
You probably would need to register a key press listener that checks if this field is selected, and if it is, ignores key presses for invalid characters. — Tripp Kinetics, Nov 20 '15 at 15:52
Because it is better than nothing for inputting integers. it deletes characters which are not numbers after selecting next jtf(after jtf unfocused/unselected letters inputted disappear from input). — Vyacheslav, Nov 20 '15 at 15:53

score 0 · Answer 1 · edited May 23 '17 at 12:15

I found a solution in possible duplicates for that question Restricting JTextField input to Integers

    NumberFormat format = NumberFormat.getIntegerInstance();
    format.setGroupingUsed(false);

    NumberFormatter numberFormatter = new NumberFormatter(format);
    numberFormatter.setValueClass(Long.class); 
    numberFormatter.setAllowsInvalid(false); //this is the key

    JFormattedTextField jFormattedTextField = new JFormattedTextField(numberFormatter);

score 0 · Answer 2 · edited May 23 '17 at 12:30

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It has been some time since I have worked on Swing, but I think you can create your own Document and set it on the JTextField.

Then in the document object you can control which characters are accepted and rejected as the user types them in.

Here is an example setting a filter on a document:

Restricting JTextField input to Integers

edited May 23 '17 at 12:30

Community

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answered Nov 20 '15 at 16:16

mjstam

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score 0 · Answer 3 · answered Nov 20 '15 at 16:24

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I would use a JSpinner configured with a JSpinnerNumberModel. This is specifically designed for integer input, and also gives the benefit of up/down arrow buttons for changing with the mouse.

answered Nov 20 '15 at 16:24

dsh

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I need text box without arrows – Vyacheslav Nov 20 '15 at 17:31

How to input integer number in Swing?

3 Answers3