StringBuffer.reverse();

public class MainClass {
  public static void main(String args[]) {
    StringBuffer sb1 = new StringBuffer("abcde");
    sb1.append("abcdefghij");
    StringBuffer sb2 = sb1.reverse();
    System.out.println(sb1);
    System.out.println(sb2);
  }
}

Why the fuck is jihgfedcbaedcba also being assigned to sb1?

>>3
That's why you read the API. It reverses in place, and then returns a reference to this for no particular reason.
So not only do sb1 and sb2 have the same value in your example, they're the same object.