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"; }
 正確答案：true true true true false true
 

This example illustrates six points:

  • Literal strings within the same class (§8) in the same package (§7) represent references to the same String object (§4.3.1).
  • 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 (§15.28) are computed at compile time and then treated as if they were literals.
  • Strings computed at run time are newly created and therefore distinct.
  • The result of explicitly interning a computed string is the same string as any pre-existing literal string with the same contents.

 

呵呵，我是沒(méi)有能夠全部答對(duì)

 

另外一篇關(guān)于String intern的文章：

http://laiseeme.javaeye.com/blog/102442