Basics

Question 1

What three properties makes a program good?

Answer 1

1. It works
2. easy to modify
3. reasonably efficient

Question 2

What does an ADT stand for?

Answer 2

Abstract Data Type

Question 3

What does an ADT separate?

Answer 3

Specification and implementation, which improves the reusability

Question 4

What is specification in this context, and where does it lie?

Answer 4

“What kind of program we are looking at” & in the public external part

Question 5

What is implementation in this context, and where does it lie?

Answer 5

“How the operations are performed” & in the private internal part

Question 6

What does unboxing convert between?

Answer 6

Wrapper class(like Integer) to primitives(like int)

Question 7

What does boxing convert between?

Answer 7

Primitives like double to wrapper class(Double)

Question 8

What is an exception?

Answer 8

An event that occurs that disrupts flow of execution

Question 9

What are the general steps of dealing with a potential in exception?

Answer 9

1. )method causes exception
2. )throws exception
3. )handles exception

Question 10

What are the steps of throwing?

Answer 10

method on call stack where error happens throws exception then can be handled or passed down the call stack for later handling

Question 11

What types of methods forward the exception?

Answer 11

Ones without an exception handler

Question 12

What two types of exception handlers are there?

Answer 12

1. )try/catch/finally block

2. )throws @ method header with throw new exception object

Question 13

What three types of exceptions are there?

Answer 13

1. unchecked/runtime
2. error
3. checked

Question 14

What is the difference between checked and unchecked exceptions?

Answer 14

unchecked are checked at runtime while checked are not

Question 15

For a sub and super class, which direction is generalization happening?

Answer 15

creating a super class from a sub class is an example of generalization?

Question 16

Changing a wrapper class to a generic type E is an example of what?

Answer 16

generalization

Question 17

commenting improves what?

Answer 17

clarity and thus reusability

Question 18

What is a data structure?

Answer 18

A way to organize data

Question 19

when instantiating an object with a superclass what two ways are correct?

Answer 19

Subclass x = new Subclass()
Superclass x = new Subclass(), if the method requires a variable of type superclass

Question 20

What is the difference between a reference type and a primitive type?

Answer 20

a primitive type is Boolean, int, double.. and is the actual data, whereas a reference type is a pointer to a class or other piece of data

Question 21

Out of the three basic data structures, arrays, lists and trees, which are dynamic?

Answer 21

arrays, since they can’t change in size

Question 22

What is aliasing?

Answer 22

Two references that refer to the same piece of data

Question 23

What is the difference between performance and complexity?

Answer 23

performance is how much actual space is being taken up, while complexity is how much space/time is taken as the problem size grows

Question 24

What are basic operations and what are their complexities?

Answer 24

-arithmetic operations
-assignments
-writes
O(1)

Question 25

What is the worst case complexity?

Answer 25

The largest complexity an algorithm can have

Question 26

How is complexity expressed?

Answer 26

By big-O notation

Question 27

What doesn’t affect big-O?

Answer 27

low order terms, scaling and constants

Question 28

How is the exact complexity expressed?

Answer 28

T(N)

Question 29

When is a function T(N), O(F(N))?

Answer 29

if for c and all values of N greater than n, T(N) <= c * F(N)

Question 30

What is the average & best case complexity?

Answer 30

The usual complexity and the smallest that an algorithm can have, respectively

Question 31

What two different searches are there for an array?

Answer 31

1. ) binary search

2. ) sequential search

Question 32

What is the time complexity of a sequential search?

Answer 32

O(N)

Question 33

When an array is sorted what search improves the complexity?

Answer 33

binary search with a complexity of O(logN)