Can you say internally what happens?

Question

String s1 = new String("ABCDEF");
String s2 = new String("ABCDEF");
if(s1==s2){
s.o.pln("true")
}else
s.o.pln("false")
} here it gives false
String a="xxxxx";
String b="xxxxx";
if(s1==s2){
s.o.pln("true")
}else
s.o.pln("false")
} here it gives true

Answer 1

I'm not completely certain about this, but based on some of the Java certifications facts, this is what I believe it happens:
For:
String s1 = new String("ABCDEF");
String s2 = new String("ABCDEF");What happens first is that when the code reaches the first object creation, it FIRST creates the String "ABCDEF" and places it on the java pool of Strings, then your two String references (s1 and s2) points to a new String object which has a reference to the "ABCDEF" String.
A more graphical representation would look like
[String s1] ---> [String obj] ---\         //Pool
                                  \------ [ "ABCDEF" ]
[String s2] ---> [String obj] ---/So, when you compare s1 to s2 using the "==" operator (you are comparing the references, not the value) it returns false,
because s1 and s2 point to different objects, even though they have the same value.
Now
For:
String a="xxxxx";
String b="xxxxx";What happens is that when the code reaches the first object creation, it FIRST creates the String "xxxxx" and places it on the pool, then both references (a, b) point directly to that String object in the pool.
Graphically:
[String a] ---\         //Pool
               \------ [ "xxxxx" ]
[String b] ---/So now, both, a and b point to the same object and that is why the comparison using the "==" operator returns true.