Can the Tooling API be used to determine which Apex class the current Apex class extends from?

Question

Does anyone know of a way to use the Tooling API to determine which Apex class the current class extends from? I have looked at the SymbolTable but cannot see any indication that this information is revealed.

Thanks for the help.

Cheers!

Answer 1

The answer is that the Tooling API does not support this information ...at least not in v29.0

Answer 2

Here are some pure-Apex solutions for determining whether a given Apex Class extends another given Apex Class.

(Option 1) Query the ApexClass object for its Body field, and parse out the body as a string to find the class that it extends

// Query for the class definition, retrieving the class Body
ApexClass cls = [select Id,Name,Body from ApexClass where Name = 'MyApexClass' limit 1];
String body = String.valueOf(cls.Body);
String classDef = body.substring(0,body.indexOf('{'));
String classExtended;
if (classDef.contains('extends')){
    Integer extendsInitial = classDef.indexOf(' extends ');
    Integer extendsStarts = extendsInitial+9;
    Integer extendsEnds = classDef.indexOf(' ',extendsStarts);
    classExtended = body.substring(extendsStarts,extendsEnds);
    System.debug('Class ' + cls.Name + ' extends: ' + classExtended);
} else {
    System.debug('Class ' + cls.Name + ' does not extend another class');
}

You can then compare classExtended to whatever class you are wondering whether the class extends.

(Scenario 2) Use System.Type and try/catch to determine whether a given type is an instance of another type

String classToCheck = 'MyClassThatExtendsAnother';
String classExtended = 'MyBaseClass';

System.Type t = System.Type.forName(classToCheck);
MyBaseClass c;
try {
    c = (MyBaseClass) JSON.deserialize('{}',t);
} catch (Exception ex){}

if (c == null){
    System.debug('Class ' + classToCheck + ' does not extend ' + classExtended);
} else {
    System.debug('Class ' + classToCheck + ' DOES extend ' + classExtended);
}