Vocab

Question 1

Wrapper class

Answer 1

Wrapper classes provide a way to use primitive data types (int, boolean, etc..) as objects.
Use the capitals: Int not int

Question 2

Autoboxing

Answer 2

automatic conversion that the Java compiler makes between the primitive types and their corresponding object wrapper classes

Question 3

this

Answer 3

refers to the current object in the method or constructor

Question 4

new

Answer 4

used to create a new instance of a class

Question 5

Static variables

Answer 5

variables lifetime is the full time the program is running

Question 6

Static method

Answer 6

-method belongs to the class not the instance of the class
-method is accessible to every instance of a class but methods defined in an instance are only able to be accessed by that object of the class

Question 7

Instance variables

Answer 7

variable which is declared in a class but outside of constructors, methods, or blocks

Question 8

Instance Constants

Answer 8

variable whose value never changes

Question 9

Polymorphism

Answer 9

ability of a class to provide different implementations of a method, depending on the type of object that is passed to the method

Question 10

Inheritance

Answer 10

create new classes that inherit features of the superclass

Question 11

super

Answer 11

constructor call

Question 12

super.method()

Answer 12

call parent method

Question 13

default access

Answer 13

same class and same package

Question 14

private access

Answer 14

only that class

Question 15

protected access

Answer 15

Same class, same package, and different package subclass

Question 16

public access

Answer 16

yes

Question 17

abstract class

Answer 17

restricted class that cannot be used to create objects

Question 18

abstract method

Answer 18

-no body

-can only be used in an abstract class

Question 19

interface

Answer 19

-a completely “abstract class” that is used to group related methods with empty bodies
-may not have member variables or method definitions

Question 20

typecast

Answer 20

assign a value of one primitive data type to another type

Question 21

instance of

Answer 21

test whether the object is an instance of the specified type (class or subclass or interface)

Question 22

abstract class vs interface

Answer 22

Abstract classes can have methods with implementation whereas interface provides absolute abstraction and can’t have any method implementations.

Question 23

Enumerated Types

Answer 23

type whose legal values consist of a fixed set of constants
ex)fall winter spring summer

Question 24

Array

Answer 24

int[] myNum = {10, 20, 30, 40};
myNum[2];
arr = insertX(n, arr, x, pos);

Question 25

Array list

Answer 25

ArrayList<Integer> arrlist = new ArrayList<Integer>(5);
arrlist.add(15);</Integer></Integer>

Question 26

Iterated for loop

Answer 26

for (Integer number : arrlist) {
System.out.println(“Number = “ + number);
}

Question 27

Map

Answer 27

Map<Integer, String> map = new HashMap<>();
map.put(1, “One”);
map.get(Object key_element)

Question 28

Set

Answer 28

Set<Obj> set = new HashSet<Obj> ();
s.add("Welcome");
s.remove("Welcome");</Obj></Obj>

Question 29

next vs nextLine()

Answer 29

nextLine() - returns all text up to a line break
next() - returns tokenized text. The next() method uses whitespace as the default delimiter.

Question 30

throw vs throws

Answer 30

throw - throw an exception explicitly (one) throws - declare multiple exceptions, separated by a comma

Question 31

@test

Answer 31

says the next method is a test

Question 32

@Before vs @BeforeClass

Answer 32

@Before - executed before each test
@BeforeClass - runs once before the entire test fixture

Question 33

UML ——->

Answer 33

shows dependence

Question 34

UML <——->

Answer 34

shows association

Question 35

UML ____> (solid line arrow)

Answer 35

connects a specialized element with a generalized element
(inheritance)