Autoboxing and == operator

Question

Hi,
I have a problem with the following code :
public class Equivalence {
     public static void main(String args[]) {
          Integer n1 = new Integer(47);
          Integer n2 = new Integer(47);
          System.out.println(n1 == n2);
          Integer n3 = 47;
          Integer n4 = 47;          
          System.out.println(n3 == n4);
}the output is :
false
true
I don't really see the reason why the second output is false, the only thing that I can imagine, is that java create only one Integer object with the value 47 and reference it with n3 and n4 thus we have the same value for n3 and n4.
Am I correct ?
thanks

Answer 1

JosAH wrote:
Read the API documentation for the static method Integer.valueOf(int i). It is used by the compiler for autoboxing purposes. (hint: it caches certain values so no new objects are created for certain int values).Somewhat related, this is also the API recommended way of getting an Integer.
If a new Integer instance is not required, this method should generally be used in preference to the constructor Integer(int), as this method is likely to yield significantly better space and time performance by caching frequently requested values.