[SalesForce] How to get the Runtime-Type of an Object dynamically (for Primitive Data Types and SObjects)

Is it possible to get the Type of an Object (it's not an SObject)?

String s = 'test';
doSomething(s);

public static void doSomething(o Object) {
    // need to find out if o is a string or an integer
    type = IsThereAMethodToGetTheTypeOf(o) // ?
    if(type='String') {
        // do something for strings here ....
    } else {
        // do something else ....
    }
}

I think the Type class can't help me, because it has no way to get the type of an existing object instance, right? Any there any other way?

Since there is most likely no perfect solution possible within the current platform limitations, I posted an Idea on IdeaExchange here: https://success.salesforce.com/ideaView?id=08730000000l9wHAAQ

For SObject I have already this

public static string getType(SObject obj) {
    if(obj==null) return '';
    return obj.getSObjectType().getDescribe().getName()+'';
}

Best Answer

Thanks to the comment of @KeithC I was able to go on with my research and as a result, it seems not possible to get a primitive data-type dynamically as a string. There are concepts to come close to it by the usage of instance of or try/catch in brute-force-like manner.

Since the primitive types are just a few, this workaround with instanceof seems acceptable for all types excepts of collections.

For list, map and set actually I was not able to find a satisfactory solution. Brute-force is not a general option, because of infinite possibilities. String.valueOf() can give a clue but not very much: for set and map, it returns a serialization wrapped in {} and for list it's wrapped in ().

Thanks to the feedback of @sfdcfox to try instanceof List<object>, map<object, object>, and set<object>, we seem to be able to detect lists. Unfortunately it does not work for maps and sets. This are my results:

object o;
o = new map<string,object>{}; 
system.debug( o instanceof map<string,object> ); // ==> true
system.debug( o instanceof map<object,object> ); // ==> false
o = new list<string>{}; 
system.debug( o instanceof list<string> ); // ==> true
system.debug( o instanceof list<object> ); // ==> true : only here it works
o = new set<string>{}; 
system.debug( o instanceof set<string> ); // ==> true
system.debug( o instanceof set<object> ); // ==> false

Any better approaches for collections are welcome!

The documentation to this topic is rare, as @mast0r said.

This links were helpful for me coming to this conclusion:

Related Solutions

[SalesForce] Create a primitive type dynamically

It's not possible to do what you want with primitive data types, as you've pointed out you get a runtime error:

System.TypeException: String cannot be constructed

You also get the same error doing this as well:

String str = new String();

This is the case for primitives and implies that they do not have a public constructor for construction in this way (remember, you assign primitives using a literal, e.g. String str = 'str';).

The only success i've had with this type of thing is to utilise JSON and the Object type, something like:

String expr = '{"value":false}';
Map<String,Object> exprMap = (Map<String,Object>)JSON.deserializeUntyped(expr);
Object myBool = exprMap.get('value');

expr = '{"value":""}';
exprMap = (Map<String,Object>)JSON.deserializeUntyped(expr);
Object myString = exprMap.get('value');

expr = '{"value":0.0}';
exprMap = (Map<String,Object>)JSON.deserializeUntyped(expr);
Object myDecimal = exprMap.get('value');

And even this could be prone to ambiguity of some data types.

[SalesForce] Simple Apex class to return a list of strings

You can't instantiate a List like that using an integer. You don't need to explicitly specify how much items are going into the list when it is created. Instead, just remove the integer:

//Instantiate the list
String[] myArray = new List<String>();

You're logic in your loop seems to be incorrect as well. Specifically, myArray's size will always be 0 when you instantiate it. Change your loop logic to:

for(Integer i=0;i<length;i++) {
   // code
}

You want to generate a List of strings based on the i variable. You will want to change your internal logic to:

//Populate the array
myArray.add('Test ' + i);

// Write value to the debug log
System.debug(myArray[i]);

Finally, you want to return that Array. You need to change your method so the return type is no longer void by changing its signature:

public static String[] generateStringArray(Integer length)

then it is just a matter of returning that array at the end of your method:

return myArray;

This would bring it all together as:

public class StringArrayTest {
    //Public Method
    public static String[] generateStringArray(Integer length) {
        //Instantiate the list
        String[] myArray = new List<String>();

        //Iterate throught the list
        for(Integer i=0;i<length;i++) {
            //Populate the array
            myArray.add('Test ' + i);

            // Write value to the debug log
            System.debug(myArray[i]);
        } //end loop

        return myArray;
    }//end method       
}// end class

Some more info on Arrays and Lists, Loops, and Class methods for future reference.

Best Answer

Related Solutions

[SalesForce] Create a primitive type dynamically

[SalesForce] Simple Apex class to return a list of strings

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