java - Object is same but the output is different ? please help

public
            class AboutStrings{
public static void main(String args[]){
String
            s1="hello";
String s2="hel";
String s3="lo";
String
            s4=s2+s3;

//to know the hash codes of
            s1,s4.


System.out.println(s1.hashCode());
System.out.println(s4.hashCode());

//
            these two s1 and s4 are having same
            hashcodes.

if(s1==s4){
System.out.println("s1 and s4 are
            same.");
}else
System.out.println("s1 and s4 are not
            same.");

}
}

In
the above example even though s1 and s4 are refering to
same object(having
same hash codes),

it is printing s1 and s4 are
not same.

Can anybody explain in detail why it
is behaving like this?

class="post-text" itemprop="text">

class="normal">Answer

Just
because two objects have the same hash code does
not mean they are the same object (you
are checking with == the object identity!).

You
may want to
call

s1.equals(s4)

instead
- but even then, both could have the same hash code without
being equal either: two objects that are equal must have
the same hash code (to work properly in Collections etc), but not vice
versa.