Difference between Objects.hashCode() and new Object().hashCode()?

问题

What's the difference between these two code snippets?

Snippet 1:

Object o = new Object();
int i = Objects.hashCode(o);

Snippet 2:

Object o = new Object();
int i = o.hashCode();

回答1:

Tolerates null value

The only difference is that if o is null, Objects.hashCode(o) returns 0 whereas o.hashCode() would throw a NullPointerException.

回答2:

This is how Objects.hashCode() is implemented:

public static int hashCode(Object o) {
    return o != null ? o.hashCode() : 0;
}

If o is null then Objects.hashCode(o); will return 0, whereas o.hashCode() will throw a NullPointerException.

回答3:

java.util.Objects {
    public static int hashCode(Object o) {
        return o != null ? o.hashCode() : 0;
    }
}

This is a NPE safe alternative to o.hashCode().

No difference otherwise.

回答4:

Object o = new Object();
int i = Objects.hashCode(o);

It returns the hash code of a not-null argument and 0 for null argument. This case it is Object referred by o.It doesn't throw NullPointerException.

Object o = new Object();
int i = o.hashCode();

Returns the hashCode() of Object referred by o. If o is null , then you will get a NullPointerException.

来源：https://stackoverflow.com/questions/16187453/difference-between-objects-hashcode-and-new-object-hashcode