java Long determines whether a value equal to

Long a value equal to determine whether the use of "==", encountered a problem

public class Demo {
    public static void main(String[] args) {
        Long m = 1L;
        Long n = 1L;
        if (m == n) {
            System.out.println("m 等于 n");
        } else {
            System.out.println("m 不等于 n");
        }
    }
}

Export

　　m is equal to n

public class Demo {
    public static void main(String[] args) {
        Long m = 128L;
        Long n = 128L;
        if (m == n) {
            System.out.println("m 等于 n");
        } else {
            System.out.println("m 不等于 n");
        }
    }
}

Export

　　m is not equal to n

the reason:

　　If Long value between [-127,128], with "==" is an equality is determined whether no problem 

　　If you do not [-127,128] between, a new object will be new, not use "=="

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);
}

the solution

　　(1) use  . LongValue ()

public class Demo {
    public static void main(String[] args) {
        Long m = 128L;
        Long n = 128L;
        if (m.longValue() == n.longValue()) {
            System.out.println("m 等于 n");
        } else {
            System.out.println("m 不等于 n");
        }
    }
}

Export

　　m is equal to n

　　(2) using .equals ()

public class Demo {
    public static void main(String[] args) {
        Long m = 128L;
        Long n = 128L;
        if (m.equals(n)) {
            System.out.println("m 等于 n");
        } else {
            System.out.println("m 不等于 n");
        }
    }
}

Export

　　m is equal to n

supplement:

　　The best solution for .eques ()

public boolean equals(Object obj) {
        if (obj instanceof Long) {
            return value == ((Long)obj).longValue();
        }
        return false;
}