判断java标识符

Posted 2020-12-07 lingtongwanr

1 package com.jdk7.chapter5;
 2 
 3 public class JavaIdentifier {
 4     
 5     /**
 6      * 使用Character.isJavaIdentifierPart判断字符是否属于java标识符
 7         it is a letter 
 8         it is a currency symbol (such as ‘$‘) 
 9         it is a connecting punctuation character (such as ‘_‘) 
10         it is a digit 
11         it is a numeric letter (such as a Roman numeral character) 
12         it is a combining mark 
13         it is a non-spacing mark 
14         ‘u005Cu0000‘ through ‘u005Cu0008‘ 
15         ‘u005Cu000E‘ through ‘u005Cu001B‘ 
16         ‘u005Cu007F‘ through ‘u005Cu009F‘ 
17      * @param str
18      * @return
19      */
20     public static boolean isJavaIdentifier(String str){
21         if(str==null || str.length()==0){
22             return false;
23         }
24         char[] ch = str.toCharArray();
25         for(int i=0;i<ch.length;i++){
26             if(!(Character.isJavaIdentifierPart(ch[i]))){
27                 return false;
28             }
29         }
30         return true;
31     }
32     
33     public static void main(String[] args) {
34         System.out.println("my_var is an identifier? "+JavaIdentifier.isJavaIdentifier("my_var"));
35         System.out.println("$my_var is an identifier? "+JavaIdentifier.isJavaIdentifier("$my_var"));
36         System.out.println("my_var.1 is an identifier? "+JavaIdentifier.isJavaIdentifier("my_var.1"));
37         System.out.println("1$my_var is an identifier? "+JavaIdentifier.isJavaIdentifier("1$my_var"));
38         System.out.println("u0391var is an identifier? "+JavaIdentifier.isJavaIdentifier("u0391var"));
39         System.out.println("null is an identifier? "+JavaIdentifier.isJavaIdentifier(null));
40         System.out.println("null is an identifier? "+JavaIdentifier.isJavaIdentifier(" "));
41     }
42 }
43 
44 
45 执行结果：
46 my_var is an identifier? true
47 $my_var is an identifier? true
48 my_var.1 is an identifier? false
49 1$my_var is an identifier? true
50 u0391var is an identifier? true
51 null is an identifier? false
52 null is an identifier? false