String pool management summary

package testPackage;
class Test {
       public static void main(String[] args) {
               String hello = "Hello", lo = "lo";
               System.out.print((hello == "Hello") + " ");
               System.out.print((Other.hello == hello) + " ");
               System.out.print((other.Other.hello == hello) + " ");
               System.out.print((hello == ("Hel"+"lo")) + " ");
               System.out.print((hello == ("Hel"+lo)) + " ");
               System.out.println(hello == ("Hel"+lo).intern());
       }
}
class Other { static String hello = "Hello"; }

and the compilation unit:

package other;
public class Other { static String hello = "Hello"; }

produces the output:

true true true true false true

This example illustrates six points:

• Literal strings within the same class in the same package represent references to the same String object.
• Literal strings within different classes in the same package represent references to the same String object.
• Literal strings within different classes in different packages likewise represent references to the same String object.
• Strings computed by constant expressions are computed at compile time and then treated as if they were literals.
• Strings computed by concatenation at run time are newly created and therefore distinct.