String joins done by the compiler and at run time

public class Main {
    public static void main(String[] args) {
        String a = "hello";
        String b = "hel" + "lo";
        String part = "hel";
        String c = part + "lo";
        System.out.println(a == b);
        System.out.println(a == c);
        System.out.println(a == c.intern());
    }
}