java string concatenation and interning

Question

Question 1

String a1 = \"I Love\" + \" Java\";
String a2 = \"I Love \" + \"Java\";
System.out.println( a1 == a2 ); // true

String b1 = \"I Love\";
b1 += \"          


        

Answer 1

From intern() docs

All literal strings and string-valued constant expressions are interned. String literals are defined in section 3.10.5 of the The Java™ Language Specification.

And from JLS 3.10.5

• Strings computed by constant expressions (§15.28) 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.

Your string b1 not actually interned. Hence the difference.