Why object is not null in below java code? [duplicate]

Question

In below code the answer is "kjl". here the object is assigned to null. Why object is not null here?

public class Main
{
    public static void main(String[] args) {
        test tr =new test();
        tr.display(tr);
        System.out.println(tr.Name);
    }
}

class test {
    String Name = "abc";
    void display(test t) {
        t.Name = "kjl";
        t = null;
    }
}