Question

I’m using some API by restTemplate. The API returns a key whose type is integer.

But I’m not sure of that value, so I want to check whether the key is really an integer or not.
I think it might be a string.

What is the best way of checking if the value is really integer?

added:
I mean that some API might return value like below.
{id : 10} or {id : “10”}

Answer 1

Object x = someApi();

if (x instanceof Integer) 

Note that if someApi() returns type Integer the only possibilities of something returned are:

• an Integer
• null

In which case you can:

if (x == null) {
    // not an Integer
} else {
    // yes an Integer
}