判断java标识符

package com.jdk7.chapter5;

public class JavaIdentifier {
    
    /**
     * 使用Character.isJavaIdentifierPart判断字符是否属于java标识符
        it is a letter 
        it is a currency symbol (such as '$') 
        it is a connecting punctuation character (such as '_') 
        it is a digit 
        it is a numeric letter (such as a Roman numeral character) 
        it is a combining mark 
        it is a non-spacing mark 
        'u005Cu0000' through 'u005Cu0008' 
        'u005Cu000E' through 'u005Cu001B' 
        'u005Cu007F' through 'u005Cu009F' 
     * @param str
     * @return
     */
    public static boolean isJavaIdentifier(String str){
        if(str==null || str.length()==0){
            return false;
        }
        char[] ch = str.toCharArray();
        for(int i=0;i<ch.length;i++){
            if(!(Character.isJavaIdentifierPart(ch[i]))){
                return false;
            }
        }
        return true;
    }
    
    public static void main(String[] args) {
        System.out.println("my_var is an identifier? "+JavaIdentifier.isJavaIdentifier("my_var"));
        System.out.println("$my_var is an identifier? "+JavaIdentifier.isJavaIdentifier("$my_var"));
        System.out.println("my_var.1 is an identifier? "+JavaIdentifier.isJavaIdentifier("my_var.1"));
        System.out.println("1$my_var is an identifier? "+JavaIdentifier.isJavaIdentifier("1$my_var"));
        System.out.println("u0391var is an identifier? "+JavaIdentifier.isJavaIdentifier("u0391var"));
        System.out.println("null is an identifier? "+JavaIdentifier.isJavaIdentifier(null));
        System.out.println("null is an identifier? "+JavaIdentifier.isJavaIdentifier(" "));
    }
}


执行结果：
my_var is an identifier? true
$my_var is an identifier? true
my_var.1 is an identifier? false
1$my_var is an identifier? true
u0391var is an identifier? true
null is an identifier? false
null is an identifier? false