Question

What is strcpy in Java?

String s1, s2;

s1 = new String("hello");
s2 = s1; // This only copies s1 to s2.

Answer 1

This statement:

s2 = s1;

copies the value of s1 into s2. That value is just a reference, so now s1 and s2 refer to the same object. So if this were a mutable type (e.g. StringBuilder, or ArrayList) then you’d be right to be concerned.

However, String is immutable. You can’t modify the object to change its text data, so just copying the reference is sufficient. Changing the value of s2 to refer to a different string (or making it a null reference) will not change the value of s1:

String s1 = "hello";
String s2 = s1;
s1 = "Something else";
System.out.println(s2); // Prints hello

If you really want to create a new String object, you can use the constructor you’re already (needlessly) using for s1:

s2 = new String(s1);

However, that’s very rarely a good idea.