Java

Front 1

What is an Object?

Back 1

An object encapsulates state and behavior.

Front 2

What is the difference between the “client view” and the “implementer view”?

Back 2

The external/client view is the "what" part (knowing what the object does) and the internal/implementation view is the "how" part (knowing how the object does it).

Front 3

What is a “generic class”?

Back 3

A type in Java that is written to accept another type as part of itself

Front 4

What method is called in the ArrayList class to dynamically include new items?

Back 4

add()

Front 5

In the ArrayList class describe the use of the contains() method.

Back 5

Returns true if the given element is in the list

Front 6

Define “Boxing”.

Back 6

An automatic conversion from primitive data to a wrapped object of the appropriate type (e.g., an int boxed to form an Integer).

Front 7

Define “Unboxing”.

Back 7

An automatic conversion from wrapped object to its corresponding primitive data (e.g., an Integer unboxed to form an int).

Front 8

What is a “Wrapper Class”?

Back 8

A class that wraps primitive data as an object.

Front 9

What method is called in the ArrayList class to dynamically eliminate items?

Back 9

remove()

Front 10

In the ArrayList class describe the use of the size() method.

Back 10

Returns the current number of elements in the list.

Front 11

What is the problem with the following code:
for (String s : words)
{
if (s.equals(“hello”))
{
words.add(“goodbye”);
}
}

Back 11

It is illegal to modify the elements of an ArrayList while for-eaching over it.

Front 12

What is the problem with the following code:
ArrayList numbers = new ArrayList();

Back 12

Primatives cannot be specified as type parameters for generic types.

Front 13

Define the term “Comparison Function”?

Back 13

A well-defined procedure for deciding, given a pair or values, the relative order of the two values (less than, equal, or greater than)..

Front 14

Define the term “Natural Ordering”?

Back 14

The order imposed on a type by its comparison function.

Front 15

Which interface is used to implement object comparison?

Back 15

The Comparable interface.

Front 16

Define the term “Collection”?

Back 16

An object that stores a group of objects, called its elements.

Front 17

What is a List?

Back 17

An ordered collection of elements accessed by integer indexes.

Front 18

What is a Stack?

Back 18

A collection where the last element added is the first one to be removed.
(i.e. LIFO)

Front 19

What is a Queue?

Back 19

A collection where elements are removed in the order in which they were added.
(i.e. FIFO)

Front 20

What is the name of the framework that is largely contained in the package java.util?

Back 20

The Java Collections Framework.

Front 21

What is a Linked List?

Back 21

A collection that stores a list of elements in small object containers called nodes, which are linked together.

Front 22

What is an Iterator?

Back 22

An object that allows you to efficiently retrieve the elements of a list in sequential order.

Front 23

Define the acronym ADT?

Back 23

Abstract Data Type.

Front 24

What is a Set?

Back 24

A collection that stores a group of elements and prevents duplicates.

Front 25

What is a Map?

Back 25

A collection that associates objects called keys with objects called values.

Front 26

What is the purpose of the binarySearch(list, value) method of the Collections Class?

Back 26

Searches a sorted list for a given element value and returns its index.

Front 27

What are the strengths/differences between an ArrayList and a LinkedList?

Back 27

ArrayList – random access; any element can be accessed quickly; adding and removing at the end of the list is fast.
LinkedList – adding and removing at either end of the list is fast; fast add/remove during a sequential access with an iterator; no need to expand an array when full; can be more easily used as a queue.

Front 28

What is an Abstract Data Type?

Back 28

A specification of a type of data and the operations that can be performed on it.

Front 29

What are the strengths/differences between a HashSet and a TreeSet?

Back 29

HashSet – extremely fast performance for add, contains, and remove; can be used with any type of objects as its elements.
TreeSet – elements are sorted in sorted order; must be used with elements that can be compared (i.e. Integer, String).

Front 30

Why doesn’t the MAP collection have an iterator method?

Back 30

Because exactly what you wanted to iterate over wouldn’t be clear.

Front 31

What are the two major methods implemented to support operations on the Stack collection? Describe what they are designed to accomplish.

Back 31

Push() – put elements on the stack
Pop() – remove and return elements off of the stack

Front 32

What are the two major methods implemented to support operations on the Queue collection? Describe what they are designed to accomplish.

Back 32

Enqueue() – add elements to the back of the queue
Dequeue() – take elements out of the front of the queue

Front 33

What is Recursion?

Back 33

A programming technique in which you describe actions to be repeated using a methods that calls itself.

Front 34

What is a Base Case?

Back 34

A case that is so simple that it can be solved directly without a recursive call.

Front 35

What is a Recursive Case?

Back 35

A case that involves reducing the overall problem to a simpler problem of the same kind that can be solved by a recursive call.

Front 36

Define the term “fractal”.

Back 36

A mathematically generated, self-similar image.

Front 37

Who created the “fractal”?

Back 37

Created by B. Mandelbrot in 1975

Front 38

Why do we care about “fractals” in this course?

Back 38

Many can be drawn elegantly using recursive algorithms

Front 39

What is the problem with a recursive solution to the Fibonacci numbers problem?

Back 39

fibonacci(n) recomputed fibonacci(n-1 ... 1) many times in finding its answer!
this is a common case of "overlapping subproblems" or "divide poorly and reconquer", where the subtasks handled by the recursion are redundant with each other and get recomputed

Front 40

What causes “Infinite Recursion”?

Back 40

a definition with a missing or badly written base case causes infinite recursion, similar to an infinite loop
avoided by making sure that the recursive call gets closer to the solution (moving toward the base case)

Front 41

Define the term “Efficiency”.

Back 41

A measure of the computing resources used by a piece of code such as time, memory, or disk space.

Front 42

What is the efficiency of the following example?
for (N times) {
for (N times) {
statement1.
}
}
for (N times) {
statement 1.
statement 2.
}

Back 42

N^2 + 2N

Front 43

What is meant by shuffling data?

Back 43

The task of rearranging its elements into a random order. Opposite of sorting.

Front 44

What is a comparator?

Back 44

Comparators perform comparisons between pairs of objects.

Front 45

Name the two ways to determine an algorithm’s time efficiency?

Back 45

Empirical Analysis
Algorithm Analysis

Front 46

Define the term “Complexity Class”.

Back 46

A category of algorithm efficiency based upon the algorithm’s relationship to the input data size.

Front 47

Can a “Binary Search” be implemented using a recursive algorithm?

Back 47

Yes.

Front 48

Provide a high level description of the “Binary Search” algorithm.

Back 48

Split the search space in two parts using a min, mid, and max indexes. Perform successive subdivisions of the search space until the target is found.

Front 49

Provide a high level description of the “Selection Sort” algorithm.

Back 49

Makes many passes over an input array to put its elements into sorted order.

Front 50

Can a “Merge Sort” be implemented using a recursive algorithm?

Back 50

Yes.

Front 51

What is the complexity for a binary search?

Back 51

O(log n)

Front 52

What is the complexity for a hash function?

Back 52

O(1)

Front 53

What is the complexity for the following code segment?
for (int i = 0; i < N; i += c)
;

Back 53

O(N)

Front 54

What is the complexity for the following code segment?
for (int i = 0; i < N * N; i += c)
;

Back 54

O(N^2)

Front 55

What is the complexity for a merge sort?

Back 55

O(n log n)

Front 56

Define the term hashing?

Back 56

To map a value to an integer index.

Front 57

What is a hash table?

Back 57

An array that stores elements via hashing.

Front 58

What is a hash function?

Back 58

An algorithm that maps values to indexes.

Front 59

What is a collision?

Back 59

When a hash function maps two or more elements to the same index.

Front 60

Name three techniques for collision resolution?

Back 60

Probing
Clustering
Chaining

Front 61

What is a binary tree?

Back 61

A tree where each node has at most two children.

Front 62

What is the topmost node in the tree?

Back 62

root

Front 63

What is a leaf?

Back 63

A node that has no children.

Front 64

What is a branch?

Back 64

Any internal node that is not a node or a leaf.

Front 65

Name the three types of binary tree traversals?

Back 65

Preorder
Inorder
Postorder

Front 66

What are the four components in the Adapter Model?

Back 66

Client, Target, Adaptor, Adaptee

Front 67

What is the Java language equivalent of the JOptionPane?

Back 67

System.out.println();

Front 68

What are the two graphics packages available in the current Java release?

Back 68

AWT and Swing.

Front 69

Describe a two-way Adapter Model.

Back 69

A two-way adapter supports both the Target and the Adaptee interface. It allows an adapted object (Adapter) to appear as an Adaptee object or a Target object.

Front 70

Describe the motivations for using the Adapter Model?

Back 70

Sometimes a toolkit or class library cannot be used because its interface is incompatible with the interface required by an application.
 We cannot change the library interface, since we may not have its source code.
 Even if we did have the source code, we probably should not change the library for each domain-specific application

Front 71

What is a Frame?

Back 71

A graphical window on the screen.

Front 72

What is a Component?

Back 72

A widget, such as a button or text field, that resides inside a graphical window.

Front 73

What is a Layout Manager?

Back 73

A Java object that decides the positions, sizes, and resizing behavior of the components within a frame or other container on the screen.

Front 74

What is an Event?

Back 74

An object representing a user’s interaction with a GUI component, which can be handled by your programs to create interactive components.

Front 75

What is a Listener?

Back 75

An object that is notified when an event occurs and executes code to respond to that event.

Front 76

What is a metaphor for the Graphics object?

Back 76

Think of the Graphics object as a pen and the panel as a sheet of paper.

Front 77

What is the purpose of the following method?
public int getX();

Back 77

Return the x-coordinate where the mouse event occurred.

Front 78

What is the purpose of the following statement?
g.setColor(Color.RED);

Back 78

To set the color of the next graphics object to RED.

Front 79

There are new packages that you must import when writing graphical programs. Write the import statements necessary to use them.

Back 79

import java.awt.*;
import javax.swing.*;

Front 80

What class should be extended when drawing 2D graphics?

Back 80

JPanel