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Java Java Data Structures - Retired Getting There Type Casting

Posted by Stephanie Fu
Stephanie Fu
1,939 Points

2 questions about typecasting and the array Craig created

At about 3:30 in the video, Craig adds (Treet) in front of the someStuff array. Is this because as an object, someStuff doesn't have access to the getDescription() method, and the only way to access the method is to turn it into a Treet?

When the array was declared as an Object[], does that mean the array itself is an object, or is the variable an array of objects?

2 Answers

Alex White
Alex White
16,750 Points
Alex White
Alex White
16,750 Points

The variable is an Array of Objects

Abhinav Kanoria
Abhinav Kanoria
7,730 Points
Abhinav Kanoria
Abhinav Kanoria
7,730 Points

  1. Yes, you need to typecast the 'Object' to a 'Treet'. This is because the method getDescription() i=belongs to the 'Treet' class and not the 'Object' class. Object class is the superclass(parent) of 'Treet' class but the method getDescription() belongs specifically to 'Treet' class. That's why you need to typecast it to a 'Treet' object before you can call that method. This is similar to writing : String result = (BlogPost)obj.getTitle(); if you've attempted the task 2 of the challenge just after this video. In the above line of code, you need to typecast 'obj' to 'BlogPost' so that you can call the method getTitle() which belongs to 'BlogPost' class exclusively.

  2. By declaring Object[] someStuff, we are declaring an array of Objects. This means that it can hold objects of different types such as 'Treet', 'String', 'BlogPost', 'PezDispenser', 'Bicycle' and any other real life object that you've created.

Hope this helps!