In Java, are parameters passed by reference or by value?

Hi everyone! I just started learning Java and encountered some confusion. Books say that in Java everything is passed by value, but in practice I see something strange. Here's an example. When I pass an object (e.g., a list) to a method and modify it inside the method, the changes persist after exiting the method: ```java public class Test { public static void main(String[] args) { StringBuilder sb = new StringBuilder("Hello"); changeString(sb); System.out.println(sb); // Output: Hello World } public static void changeString(StringBuilder s) { s.append(" World"); } } ``` Here sb was changed. I thought that if a copy is passed, the changes should be local. So it turns out that objects are passed by reference? But if I try to assign