验证JTextField值，使其以“RA”开头。然后有8位数 [英] Validate JTextField value so that it starts with "RA" then has 8 digits

问题描述

我有一个 JTextField 用户必须在哪里输入数据。它的值必须始终以 RA 开头，并且后面必须有8位数字。所以，它的长度总是10。例如， RA12345678 。

I have a JTextField where in the user has to input the data. Its value has to always start with RA and must have exactly 8 digits after it. So, its length will be 10 always. for e.g., RA12345678.

我如何用Java做到这一点？

How do I do this in Java?

我尝试使用 MaskFormatter 和 JFormattedTextField 但是，没有达到效果。我需要一起验证输入的长度。

I tried using MaskFormatter and JFormattedTextField but, did not achieve the results. I need to validate the input with length together.

推荐答案

我使用 JSpinner 为此，只需在数字前加上 RA 。 EG

I'd use a JSpinner for this, and simply prefix RA to the number. E.G.

RA8007006

代码

Code

import java.awt.*;
import javax.swing.*;

class CaptureRA {

    public static void main(String[] args) {
        Runnable r = new Runnable() {

            @Override
            public void run() {
                String prefix = "RA";
                JPanel gui = new JPanel(new FlowLayout(4));
                gui.add(new JLabel(prefix));
                SpinnerModel ints = new SpinnerNumberModel(
                        1000000,1000000,99999999,1);
                JSpinner spinner = new JSpinner(ints);
                gui.add(spinner);

                JOptionPane.showMessageDialog(null, gui);
                System.out.println(prefix + ints.getValue());
            }
        };
        // Swing GUIs should be created and updated on the EDT
        // http://docs.oracle.com/javase/tutorial/uiswing/concurrency/initial.html
        SwingUtilities.invokeLater(r);
    }
}

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