Does intern add Strings to String Constant pool?

Asked Oct 28 '15 at 14:46

Active Oct 28 '15 at 14:46

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As per the Java docs Specification-

When the intern method is invoked, if the pool already contains a string equal to this String object as determined by the equals(java.lang.Object) method, then the string from the pool is returned. Otherwise, this String object is added to the pool and a reference to this String object is returned.

Why doesn't the following code create a literal in Constant pool when interned?

String a = "abc"; String b = a.substring(1); b.intern();

Why shouldn't be "bc" added to the String Constant pool.

asked Oct 28 '15 at 14:46

Arijit Dasgupta

1

Don't confuse literals in the class constants with the String `intern` pool. – Sotirios Delimanolis Oct 28 '15 at 14:47
But `b.intern();` fetches the reference of the available String from the Constant pool – Arijit Dasgupta Oct 28 '15 at 14:51
1

do you expect that `b.intern()` changes the class file? – wero Oct 28 '15 at 14:52
No, it doesn't. It has its own pool to which Strings from the class constant pool (which isn't really a pool, it's constant) are added. – Sotirios Delimanolis Oct 28 '15 at 14:53
@SotiriosDelimanolis So, `String a = "abc"; String b = a.substring(1); b.intern(); String c = "bc"; System.out.println(b==c)' results in true? – Arijit Dasgupta Oct 28 '15 at 14:59
Question makes no sense. The literal is clearly present in the constant pool dump and String.intern is completely unrelated. – Durandal Oct 28 '15 at 15:03
@SotiriosDelimanolis If we write, `String a = "abc"; String b = "abc";` As the literals are interned, will the reference of b fetched from intern pool or Constant pool? – Arijit Dasgupta Oct 28 '15 at 15:19

Does intern add Strings to String Constant pool?

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