Java隻允許輸入數字的文本框 – JAVA編程語言程序開發技術文章

[java]
package com.han; 
 
import javax.swing.JTextField; 
import javax.swing.text.AttributeSet; 
import javax.swing.text.BadLocationException; 
import javax.swing.text.Document; 
import javax.swing.text.PlainDocument; 
 
/**
 * Customized fields can easily be created by extending the model 
 * and changing the default model provided. For example, 
 * the following piece of code will create a field that holds only 
 * digit characters. It will work even if text is pasted into from 
 * the clipboard or it is altered via programmatic changes.
 * @author HAN
 *
 */ 
public class DigitOnlyField extends JTextField { 
      
   
 
    /**
     * 
     */ 
    private static final long serialVersionUID = 8384787369612949227L; 
 
    public DigitOnlyField(int cols) { 
        // super() 可以被自動調用，但是有參構造方法並不能被自動調用，隻能依賴  
        // super關鍵字顯示地調用父類的構造方法  
        super(cols); 
    }   www.aiwalls.com
 
    protected Document createDefaultModel() { 
        return new UpperCaseDocument(); 
    } 
 
    static class UpperCaseDocument extends PlainDocument { 
 
        /**
         * 
         */ 
        private static final long serialVersionUID = -4170536906715361215L; 
 
        public void insertString(int offs, String str, AttributeSet a) 
            throws BadLocationException { 
 
            if (str == null) { 
                return; 
            } 
            char[] upper = str.toCharArray(); 
            String filtered = ""; 
            for (int i = 0; i < upper.length; i++) { 
                if (Character.isDigit(Character.codePointAt(upper, i))){ 
                    filtered += upper[i]; 
                } 
            } 
            super.insertString(offs, filtered, a); 
        } 
    } 
} 
作者：Gaowen_HAN