如何验证jtextfield只接受整数 [英] how to validate a jtextfield to accept only integer numbers

问题描述

可能重复：

将JTextField输入限制为整数

检测JTextField取消选择事件

我需要验证 JTextField 允许用户只输入整数值，如果用户输入除数字以外的任何字符，则应显示 JOptionPane.show 消息框，显示该值输入不正确，只允许整数。我已将其编码为数字值，但我还需要丢弃字母

i need to validate a JTextField by allowing the user to input only integer values in it if user enters any char other than numbers a JOptionPane.show messagebox should appear showing that the value entered are incorrect and only integer numbers are allowed. I have coded it for a digit values but i also need to discard the alphabets

public void keyPressed(KeyEvent EVT) {
    String value = text.getText();
    int l = value.length();
    if (EVT.getKeyChar() >= '0' && EVT.getKeyChar() <= '9') {
        text.setEditable(true);
        label.setText("");
    } else {
        text.setEditable(false);
        label.setText("* Enter only numeric digits(0-9)");
    }
}

推荐答案

使用JFormattedTextField，您可以使用仅允许整数的文档编写自定义JTextField。我喜欢格式化的字段只用于更复杂的掩码...
看看。

Instead of using a JFormattedTextField, you may write a custom JTextField with a document that allows only integers. I like formatted fields only for more complex masks... Take a look.

import javax.swing.JTextField;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.Document;
import javax.swing.text.PlainDocument;

/**
 * A JTextField that accepts only integers.
 *
 * @author David Buzatto
 */
public class IntegerField extends JTextField {

    public IntegerField() {
        super();
    }

    public IntegerField( int cols ) {
        super( cols );
    }

    @Override
    protected Document createDefaultModel() {
        return new UpperCaseDocument();
    }

    static class UpperCaseDocument extends PlainDocument {

        @Override
        public void insertString( int offs, String str, AttributeSet a )
                throws BadLocationException {

            if ( str == null ) {
                return;
            }

            char[] chars = str.toCharArray();
            boolean ok = true;

            for ( int i = 0; i < chars.length; i++ ) {

                try {
                    Integer.parseInt( String.valueOf( chars[i] ) );
                } catch ( NumberFormatException exc ) {
                    ok = false;
                    break;
                }


            }

            if ( ok )
                super.insertString( offs, new String( chars ), a );

        }
    }

}

<如果您使用NetBeans构建GUI，只需要在GUI和创建代码中放置常规JTextField，就可以指定IntegerField的构造函数。

If you are using NetBeans to build your GUI, you just need to put regular JTextFields in your GUI and in the creation code, you will specify the constructor of IntegerField.

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