Short initialize

[nimo frey]

I want to use a Short:


I must declare it explicitly:

Short a = 1;

Is there a way to init it implicitly within code?

Something like:

(Short) 1

[Rob Spoor]

Have you tried it?

public class Test
{
    public static void main(String[] args)
    {
        doSomething(1);
        doSomething((short)1);
    }
 
    public static void doSomething(int i)
    {
        System.out.println("int " + i);
    }
 
    public static void doSomething(short s)
    {
        System.out.println("short " + s);
    }
}

[nimo frey]

This works:

(short) 1
 
(s is lower case)

but this works not:

(Short) 1

I need Short.

[Campbell Ritchie]

There is a bit about boxing and unboxing here. Read that and see whether it provides what you want.

[Bill Shirley]

You can't cast a primitive to an object.
There is no such thing as a short literal, so you must cast an int/long literal to a short - i.e. (short)1

Read the link above on auto[un]boxing to understand how Java 5 added conversions to/from primitives/objects in very specific conditions.

If you want to be specific (and verbose) about what you're doing:

Short myShortObject = new Short((short)1);

will get done what you want.

[Rob Spoor]

Originally posted by Bill Shirley:
You can't cast a primitive to an object.

Actually you can since Java 5 with autoboxing. For instance, the following is perfectly legal:

Object o = 5;

This is because 5 gets autoboxed to an Integer, which can be implicitly cast to Object without a problem. Of course there are limitations. For instance, widening then boxing won't work:

int i = 5;
Long l1 = i; // won't compile
Long l2 = 5; // won't compile - 5 is an int
Long l3 = 5L; // compiles just perfectly
Long l4 = (long)5; // compiles just perfectly because of explicit casting then autoboxing

If you want to be specific (and verbose) about what you're doing:

Short myShortObject = new Short((short)1);

will get done what you want.

I'd choose Short.valueOf instead of new Short, because it uses caching for all numbers between -128 and 127 (inclusive). The same applies to Byte, Integer and Long.
[ October 09, 2008: Message edited by: Rob Prime ]

[Alan Moore]

I think Bill meant that you can't explicitly cast from a primitive type to a reference type. In your examples, Rob, the change from primitive to object is always effected by means of an automatic boxing conversion, not an explicit cast like (Short)1.

What I wonder, nimo frey, is why you're using a Short in the first place. As a general rule, you should only use the primitive wrapper types (Short, Integer, Boolean, etc.) when you have to. Using primitives (short, int, boolean, etc.) whenever possible will tend to make your code more efficient, more readable, and less buggy. If you need to use the value in a place where an object is required, like storing it in a List, autoboxing will convert it for you at that time.