Problem in checking palindrome using reverse string method in java

Question

this code is not working properly, I tried this code with string "level" still it's executing the else statement
CODE -

import java.util.*;

public class rough {
static String reverse_checker(String a){
    String reverse = "";
    int b =a.length()-1;
    while(b!=-1){
        reverse+=a.charAt(b);
        b--;           
    }
    return reverse;
}
public static void main(String[] args) {
    System.out.println("Enter the string to check wheter its a palindrome or not -: ");
    Scanner sc = new Scanner(System.in);
    String str = sc.next();
     if(str==reverse_checker(str)){
         System.out.printf("yes the String %s is a palindrome",str);
     }else{
         System.out.printf("NO the String %s is not a palindrome",str);
     }
    sc.close();
 } 

}