Cards from Crash Course

Question 1

Can you access List items by position?

Answer 1

Yes

Question 2

Can you add items to the end of a list, or in the middle? or the beginnin?

Answer 2

Yes

Question 3

Can you replace items on the array at a certain position?

Answer 3

Yes

Question 4

Do you access the number of items in a list by .size() or .length()?

Answer 4

.size()

Question 5

Does this compile? What is “List”?

Answer 5

Yes. An interface.

Question 6

What’s the method used to put items on a List?

Answer 6

.add();

Question 7

How would you find something on a list by an index? Which method would you use?

Answer 7

.get(0);

Question 8

Why doesn’t this compile?
List names = new ArrayList<>();
names.add(“Jedd”);
names.add(“Lomin”);

String name =names.get(0);

Answer 8

The object in names may not always be a string, so the compiler will work to prevent you from messing up. If you went List it would work.

Question 9

Will this compile?
List names = new ArrayList<>();
names.add(“Jedd”);
names.add(“Lomin”);

String name = names.get(0);

Answer 9

no
names.get(0); may not always be a String so the compiler will not let you do this. If you gave List names a type of String (List names) then you would be fine.

Question 10

What is the classCastException about?

Answer 10

It’s when you try to cast something into a data type that it can’t be cast into.

Question 11

Does this work?
List names = new ArrayList<>();
names.add(“Jedd”);
names.add(“Lomin”);

	String name = names.get(0);

	System.out.println(names);

Answer 11

yeah that’s fine

Question 12

Does this compile? why or why not?

List numbers = new ArrayList<>();

Answer 12

cannot make a list of a primitive

Question 13

Does this compile?
List names = new ArrayList<>();
names.add(“Jedd”);
names.add(“Lomin”);

	String name = names.get(0);

	System.out.println(names);
	System.out.println(names.contains("Jedd"));

Answer 13

Yes

Question 14

Under what condition would you not be able to sue the contains() method?

Answer 14

If the object doesn’t implement that method.

Question 15

Does this compile?

public static void main(String… strings) {
List names = new ArrayList<>();
names.add(“Jedd”);
names.add(“Lomin”);
System.out.println(getLongNames(names).size());
}

public static List getLongNames(List list){
	List results = new ArrayList<>(list);
	return results;
}

Answer 15

Yes. It’s fine. Demonstartes how you can build a list with an argument.

Question 16

Are the error messages from Lambdas sometimes obscure?

Answer 16

Yes

Question 17

Can you make a lambda using an interface with more than one abstract method?

Answer 17

no

Question 18

What is generalization?

Answer 18

The idea that allows you to write code on a general concept, and then have that code work in specializations without having to make any additional changes.

Question 19

What is the difference between interface inheritance and implementation inheritance?

Answer 19

Interface inheritance is about fulfilling a promise or contract. What is inherited is an obligation.

Implementation inheritance, or when you extend a class, provides the method along with the code body to provide how the method is to work.

Question 20

What are two examples of interface inheritance?

Answer 20

Abstract classes and interfaces