What are the Java semantics of an escaped number in a character literal, e.g. '\15' ?

Question

Please explain what, exactly, happens when the following sections of code are executed:

int a=\'\\15\';
System.out.println(a);

this prints

Answer 1

The notation \nnn denotes an octal character code in Java. so int a = '\15' assigns the auto-cast'ed value of octal character 15 to a which is decimal 13.