【java】实现一个简单的正则：判断一个字符串是否全由数字组成

 package 正则;

 public class TestIsNum {
     public static void main(String[] args) {
         String s1="abc";
         String s2="987652345678009876543211234567890";
         String s3="a5678";
         String s4="23456789j";
         System.out.println(isNums(s1));
         System.out.println(isNums(s2));
         System.out.println(isNums(s3));
         System.out.println(isNums(s4));
         System.out.println(isNumsGoodMethod(s1));
         System.out.println(isNumsGoodMethod(s2));
         System.out.println(isNumsGoodMethod(s3));
         System.out.println(isNumsGoodMethod(s4));

     }
     public static boolean isNums(String arr){
         char[] charArray=arr.toCharArray();
         char[] nums={'0','1','2','3','4','5','6','7','8','9'};
         for(int i=0;i<charArray.length;i++){
             for(int j=0;j<nums.length;j++){
                 if(charArray[i]==nums[j]){
                     break;
                 }
                 if(j==nums.length-1){
                     return false;
                 }
             }
         }
         return true;
     }
     public static boolean isNumsGoodMethod(String arr){
         char[] charArray=arr.toCharArray();
         for(char c:charArray){
             if(c>'9'||c<'0')
                 return false;
         }
         return true;
     }
 }