string pool

[Kendall Ponder]

The output from the following code is: true false

class Class1 {

	public static void main(String...www){
		String s1 = "Test";
		String s2 = "Test";
		System.out.println(s1==s2);
		s1 = s1.replace('T','t');
		s2 = s2.replace('T','t');
		System.out.println(s1==s2);
	}
}

I take that to mean replace forms a new string object but does not put the object in the string pool in the same way new String("Test"); would not put the "Test" string in the string pool. Am I correct?

[Roel De Nijs]

Only String literals (compile time constants) are added to the String Constant/Literal Pool (hence the name of the pool ).

So both replace methods create a String at runtime and are not added to the String Constant/Literal Pool. That's why you'll get false on line9.

If you want to add a String created at runtime to the String Constant/Literal Pool, you could use the intern method.

s1 = s1.intern();
System.out.println(s1==s2); // false
System.out.println(s1==s2.intern()); // true
System.out.println(s1==s2); // false

Hope it helps!
Kind regards,
Roel

(Disclaimer: you don't need to know the intern method for the OCA exam, I just mentioned it for completeness)

[Kendall Ponder]

Thanks!