CODEWITHSUNDEEP
javaif-statementinstanceof
Something
Something

Reputation: 31

The equivalent of instanceof

What is the equivalent of this without using instanceof? Maybe something more simple while using true, false or else statements? 

public static void p (Object...ar)
{
        for (int i=0; i < ar.length; i++)
        {
                if (ar[i] instanceof int[])
                {

Upvotes: 1

Views: 2565

Answers (7)

acdcjunior
acdcjunior

Reputation: 135762

For primitive arrays you can, instead of:

if (ar[i] instanceof int[])

Use:

if (ar[i].getClass() == int[].class)



Note: The above code works fine for arrays of primitive types. Please be aware, though, that instanceof also checks if the object in the left-part is a subtype of the class in the right-part, while == does not.
For objects, the equivalent to (myInstance instanceof MyClass[]) (checks for subtyping) is:

(   MyClass[].class.isAssignableFrom(  myInstance.getClass()  )   )

Upvotes: 5

Kurohige
Kurohige

Reputation: 333

use isAssignableFrom

public static void test(Object... args) {
    for (int i = 0; i < args.length; i++) {
       if (args[i].getClass().isAssignableFrom(int[].class)) {
        System.out.println("true");
       } else {
            System.out.println("false");
       }
    }
}

you can use isAssignableFrom in a dynamic way too, see this post to know the difference between instanceof and isAssignableFrom What is the difference between instanceof and Class.isAssignableFrom(...)?

Upvotes: 0

Jonathan Drapeau
Jonathan Drapeau

Reputation: 2610

Class<?> intArrayCls = int[].class;

...

if (intArrayCls.isInstance(ar[i])) {

Would do the trick too.

JavaDoc of isInstance. It is a little more flexible as it doesn't just test equality like the accepted answer.

Upvotes: 0

hamid
hamid

Reputation: 2079

You could use: 

(getClass().isArray())

and checking if integer array:

 ar.getClass().toString().equals("class [I")

updated:

if(ar.getClass().isArray()) {
        if(ar[i].getClass() == int[].class)
            ....
        else if(ar[i].getClass() == String[].class)
            ....
}

Upvotes: 1

user949300
user949300

Reputation: 15729

Check out java.lang.Class, which has a method isAssignableFrom(Class<?> cls)

For your specific example with arrays, it also has isArray() and getComponentType()

Upvotes: 0

Eric
Eric

Reputation: 97571

Another option would be to just assume it is an int[], and catch the resulting exception if it is not:

public static void p (Object...ar)
{
    for (int i=0; i < ar.length; i++)
    {
        int[] i_arr;
        try {
            i_arr = (int[]) ar[i];
        } catch (ClassCastException e) {
            continue;
        }
        //...

Upvotes: 1

Chris Chambers
Chris Chambers

Reputation: 1365

Generally, inheritance and polymorphism is a better solution to your problem. Rather than check what kind of object you are dealing with, have several classes inherit from a generic class, and call the shared methods.

Upvotes: 0

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