== checks for reference equality, however when writing code like:
Integer a = 1;
Integer b = 1;
Java is smart enough to reuse the same immutable for a and b, so this is true: a == b. Curious, I wrote a small example to show where java stops optimizing in this way:
public class BoxingLol {
public static void main(String[] args) {
for (int i = 0; i < Integer.MAX_VALUE; i++) {
Integer a = i;
Integer b = i;
if (a != b) {
System.out.println("Done: " + i);
System.exit(0);
}
}
System.out.println("Done, all values equal");
}
}
When I compile and run this (on my machine), I get:
Done: 128