Why are 2 Long variables not equal with == operator in Java?

== compares references, .equals() compares values. These two Longs are objects, therefore object references are compared when using == operator.

However, note that in Long id1 = 123L; literal value 123L will be auto-boxed into a Long object using Long.valueOf(String), and internally, this process will use a LongCache which has a [-128,127] range, and 123 is in this range, which means, that the long object is cached, and these two are actually the same objects.

because == compares reference value, and smaller long values are cached

 public static Long  valueOf(long l) {
     final int offset = 128;
     if (l >= -128 && l <= 127) { // will cache
         return LongCache.cache[(int)l + offset];
     }
     return new Long(l);
 }

so it works for smaller long values

Also See

• Integer wrapper class and == operator - where is behavior specified?