import java.lang.reflect.Field;

public class Foo {
    static {
        try {
            Integer three = 3;
            Field value = Integer.class.getDeclaredField("value");
            value.setAccessible(true);
            value.setInt(three, 4);
        } catch (NoSuchFieldException | IllegalAccessException ignored) {
        }
    }

    public static void main(String... args) {
        Integer three = 3;
        Integer four = 4;
        System.err.println(three.equals(four));
    }
}