In short, the intern method returns a string that has the same contents as the calling string.
FROM THE API
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intern
public String intern()Returns a canonical representation for the string object.
A pool of strings, initially empty, is maintained privately by the class String.
When the intern method is invoked, if the pool already contains a string equal to this String object as determined by the equals(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.
It follows that for any two strings s and t, s.intern() == t.intern() is true if and only if s.equals(t) is true.
All literal strings and string-valued constant expressions are interned. String literals are defined in �3.10.5 of the
Java Language Specification
Returns:
a string that has the same contents as this string, but is guaranteed to be from a pool of unique strings.