Who can explain the result? Java basic
===

    public class LianXi1 
    { 
       public static void main(String args[]) 
       { 
         int a=12; 
         int b=23; 
         System.out.println("case 1"+a); //
    
         System.out.println("case 2"+b); //
    
       } 
    } 


The result is below:

    @ubuntu:~/mycode/test$ java LianXi1 
    case 112
    case 223

But I don't understand the result, who can help?
Thanks!