Operator == & method equals(), String & String Object

public class HelloWorld{

    static String s1="geeks";
    static String s2="eeksg";
    static int counter=0;
    static void checkString(String str1,String str2){
      
      if(counter<str1.length() && str1!=null && str2!=null){
        
        if(str1.equals(str2)){
          System.out.println(str1+"=="+str2+":"+str1.equals(str2));
        }else
        {
          counter++;
          checkString(str1.substring(1,str1.length())+str1.charAt(0),str2);
        }
      }
    }
     public static void main(String []args){
       checkString(s1,s2);
       //System.out.println(s1.substring(1,s1.length())+s1.charAt(0));
     }
}

HelloWorld.java

apply plugin:'application'
mainClassName = 'HelloWorld'

run { standardInput = System.in }
sourceSets { main { java { srcDir './' } } }

repositories {
    jcenter()
}

dependencies {
    // add dependencies here like following
    // compile group: 'org.apache.commons', name: 'commons-lang3', version: '3.9'
}
