The following segment of code interns a string.

String str1="my";
String str2="string";
String concat1=str1+str2;
concat1.intern();

System.out.println(concat1=="mystring");

The expression concat1=="mystring" returns true because concat1 has been interned.

If the given string mystring is changed to string as shown in the following snippet.

String str11="str";
String str12="ing";
String concat11=str11+str12;
concat11.intern();

System.out.println(concat11=="string");

The comparison expression concat11=="string" returns false. The string held by concat11 doesn't seem to be interned. What am I overlooking here?

I have tested on Java 7, update 11.