Study Guide

Question 1

What is Compilation

Answer 1

The process a computer takes to convert high level language to machine code

Question 2

What does it mean for Java to be strongly typed?

Answer 2

Every variable must be declared with a data type

Question 3

What are primitive types?

Answer 3

Specifies the size and type of variable values and has no additional methods

Question 4

What are the 8 primitive types in Java

Answer 4

byte
short
int
long
float
double
boolean
char

Question 5

What is a method?

Answer 5

A collection of statements grouped together to perform an operation

Question 6

What does ‘return’ do?

Answer 6

Finishes the execution of a method and returns a value

Question 7

What is a return type?

Answer 7

A data type of the value returned from the method

Question 8

What does the return type ‘void’ mean?

Answer 8

A method doesn’t return a value or contain a return statement

Question 9

What is a method parameter?

Answer 9

Values passed into a method to manipulate

Question 10

What are the different boolean operators?

Answer 10

== Equal to
!= Not equal to
> Greater than
< Less than
>= Greater than or equal to
<= Less than or equal to
&& Logical and
|| Logical or
! Logical not

Question 11

What are Strings in Java?

Answer 11

Sequences of characters represented as an instance of the java.lang.String class

Question 12

What is a Stack Trace?

Answer 12

List of method calls the application was in the middle of when an Exception was thrown

Question 13

What is the main method?

Answer 13

Starting point for the JVM (Java Virtual Machine) to start execution of a Java program

Question 14

What is the Syntax of the main method?

Answer 14

public static void main( String args[] ) {

{

Question 15

What is OOP?

Answer 15

Object Oriented Programming. It organized software design around Data or Objects, rather than functions and logic

Question 16

What are Objects?

Answer 16

Instances of a class

Question 17

What makes an Object different from a Primitive Type?

Answer 17

Objects are user-defined, default value is null, kept in a heap, and the reference variable is kept in the stack

Primitive Types are pre-defined, can’t contain null value as the default, and kept in the stack

Question 18

What is the relationship between a Class and an Object in Java?

Answer 18

Objects are the instances of Classes.
Classes are the “blueprint” for Objects

Question 19

What are constructors?

Answer 19

Special methods used to initialize Objects

Question 20

What is the default constructor?

Answer 20

Java compiler automatically creates a no arg constructor if we do not create any constructors

Question 21

What is an Array?

Answer 21

A collection of similar data elements stored at contiguous memory location. Can be accessed directly by it’s index value

Question 22

How do I get an element of an Array?

Answer 22

Calling the index number.

String[] fruit = {apple, orange, bananan};

System.out.println(fruit[1]); // gets element “orange”

Question 23

What are the different flow control statements in Java?

Answer 23

if statements
for loops
while loops
do while loops
switch statements

Question 24

How is a for loop written in Java?

Answer 24

for(int i = 0; i < 5; i++){
some code
}

Question 25

What is the difference between ++i and i++

Answer 25

++i pre-increment: we want to increment the value by one then use it i++ post-increment: we want to use the value then increment it by one

Question 26

What is the difference between a while loop and a do-while loop?

Answer 26

A do while loop runs through the loop at least once before checking the condition. A while loop must pass the condition before running through the loop

Question 27

What are break statements?

Answer 27

They are used to terminate the enclosing loop

Question 28

What are continue statements?

Answer 28

They skip the rest of the loop where it is declared and then executes another iteration of the loop

Question 29

What is JUnit?

Answer 29

A unit testing framework for Java with the idea of "first testing then coding"

Question 30

What is a unit test?

Answer 30

Individual units of source code that are tested to determine if they are fit for use

Question 31

What are some annotations used in JUnit?

Answer 31

@test @Before @BeforeClass @After @AfterClass @Ignores @Test(timeout=500) @Test(expected=IllegalArgumentException.class)

Question 32

What is TDD?

Answer 32

Test-Driven Development: A process of relying on software requirements converted to test cases before being developed

Question 33

What are Exceptions in Java?

Answer 33

Unwanted or unexpected events that occur during the execution of a program

Question 34

How are Errors different from Exceptions?

Answer 34

Error is used to indicate errors having to do with the runtime environment itself. They indicate a serious problem that a reasonable app should not try to catch. Exceptions indicate conditions that an application might try to catch.

Question 35

What is the difference between checked and unchecked Exceptions?

Answer 35

Checked exceptions are checked at compile time by the compiler. You should use the 'throws' keyword. Unchecked exceptions are not checked at compile time and is up to the programmer to specify how to catch these exceptions

Question 36

What might cause a NullPointerException?

Answer 36

When an application attempts to use an object reference that has a null value

Question 37

Is ArrayIndexOutOfBoundsException a runtime exception?

Answer 37

Yes, the compiler does not check for this error during compilation

Question 38

Is FileNotFoundException a runtime exception?

Answer 38

No, it is checked during compilation so it is a checked exception

Question 39

How do I find where an exception was thrown in a program?

Answer 39

In the exception stacktrace

Question 40

What does 'throws' do?

Answer 40

Indicates what exception type may be thrown by a method

Question 41

What does try/catch do?

Answer 41

Tries a risky block of code that might cause an exception and catches the exception to continue the program instead of terminating

Question 42

Can I have multiple catch blocks? Multiple try blocks?

Answer 42

Yes but each try block must be followed by a catch

Question 43

What are Collections in Java?

Answer 43

Group of individual objects which are represented as a single unit

Question 44

What is the difference between a List and a Set?

Answer 44

Lists are indexed and allows duplicates Sets are unordered and can't have any duplicates

Question 45

What is the difference between a Set and a Map?

Answer 45

Both don't allow duplicates and are unordered, however Maps allow any number of null values while Sets can only contain one

Question 46

What is the difference between a Stack and a Queue?

Answer 46

Stacks are Last In First Out: the elements inserted at the last index is the first element to come out of the list Queues are First In First Out: elements inserted at the first position are the first to come out

Question 47

What is the difference between ArrayList and LinkedList?

Answer 47

ArrayLists store only similar data types and LinkedLists can store any type of data

Question 48

Are Maps part of the Collection Interface?

Answer 48

No since map require key-value pairs

Question 49

What is a wrapper class?

Answer 49

Class whos Object wraps or contains primitive data types

Question 50

What do access modifiers do?

Answer 50

Sets access levels for classes, variables, methods, and constructors

Question 51

What are the 4 access modifiers?

Answer 51

Default: When not explicitly declared, available to any other class in the same package Private: Access only within the declared class itself Protected: Can be accessed only by the subclasses in other package or any class within the same package of the protected member Public: Can be accessed from any other class

Question 52

What are the non-access modifiers in Java?

Answer 52

Static Final Abstract Synchronized/Volitile

Question 53

What does Static do?

Answer 53

Creates methods that will exist independently of any instances created for the class

Question 54

What does Final do?

Answer 54

Can only be explicitly initialized once and variables can't be reassigned

Question 55

What is Scope in programming languages?

Answer 55

Defines where methods or variables are accessed in a program

Question 56

What are the different scopes in Java?

Answer 56

Class Level Method Level Block Level

Question 57

What is SQL and why is it used?

Answer 57

Structured Query Language for accessing and manipulating databases

Question 58

What are the sublanguages of SQL?

Answer 58

DDL: Data Definition Language DML: Data Manipulation Language DRL/DQL: Data Retrieval Language/Query TCL: Transaction Query Language DCL: Data Control Language SCL: Session Control Language

Question 59

Commands for DDL (Data Definition Language)

Answer 59

Create Alter Drop Truncate Rename

Question 60

Commands for DML (Data Manipulation Language)

Answer 60

Insert Update Delete

Question 61

Commands for DRL/DQL (Data Retrieval/Query Language)

Answer 61

SELECT

Question 62

What is a table in SQL?

Answer 62

A collection of related data held in a database that consists of columns and rows

Question 63

What are primary keys for?

Answer 63

Uniquely identifies each record in a table Must be unique and not null

Question 64

How do I query everything from a table?

Answer 64

SELECT * FROM table

Question 65

How do I query only the rows that meet some criteria in a table?

Answer 65

SELECT * FROM table WHERE condition

Question 66

How do I insert into a table?

Answer 66

INSERT INTO table (columns) VALUES (values)

Question 67

How do I update values in a table?

Answer 67

UPDATE table SET column = value WHERE condition

Question 68

How do I sort the results of a query in SQL?

Answer 68

SELECT * FROM table ORDER BY column ASC/DESC

Question 69

What do aggregate functions do in SQL?

Answer 69

Performs a calculation on a set of values and returns a single value

Question 70

What are some aggregate functions?

Answer 70

COUNT() MAX() MIN() AVG() ABS()

Question 71

What is the difference between drop, delete, and truncate?

Answer 71

DROP: Deletes an entire table DELETE: Deletes specific records from a table TRUNCATE: Removes all records from a table

Question 72

What is JDBC?

Answer 72

Java Database Connectivity allows programs to access database management systems

Question 73

What are the different classes/interfaces used in JDBC?

Answer 73

DriveManager Driver Statement PreparedStatement CallableStatement Connection ResultSet ResultSetMetaData

Question 74

What is DAO for?

Answer 74

Data Access Object is a structural pattern that allows us to isolate the application from the persistence layer(database)

Question 75

What is Mockito for?

Answer 75

Used to mock interfaces so that dummy functionality can be added to a mock interface that can be used in unit testing

Question 76

How are Mock Objects in Mockito created?

Answer 76

Writing methods to test followed by @TEST with a method for the expected results

Question 77

What is HTTP?

Answer 77

HyperText Transfer Protocol is a set of rules that describe how info is exchanged and allows the client and server to communicate

Question 78

What are HTTP Verbs?

Answer 78

Get Post Put Patch Delete

Question 79

What is GET usually used for?

Answer 79

Retrieves a list of entities

Question 80

What is POST usually used for?

Answer 80

Creating an entity

Question 81

What is PUT usually used for?

Answer 81

Updating an Entity

Question 82

What is PATCH usually used for?

Answer 82

Partially updating an entity

Question 83

What is DELETE usually used for?

Answer 83

Deleting an entity

Question 84

What are 100-level status codes for?

Answer 84

Informational response

Question 85

What are 200-level status codes for?

Answer 85

Successful Requests

Question 86

What are 300-level status codes for?

Answer 86

Redirection, further action needed to be taken to complete the request

Question 87

What are 400-level status codes for?

Answer 87

Client side error, request contains a bad syntax

Question 88

What are 500-level status codes for?

Answer 88

Server side error, Server failed to fulfill a bad request

Question 89

What is a path parameter?

Answer 89

Request parameters attached to a URL to point to a specific rest API resource. Appear before the question mark in the URL

Question 90

What is a query parameter?

Answer 90

Optional key-value pairs that appear after the question mark in the URL

Question 91

What is a request body?

Answer 91

Data transmitted to an HTTP transaction immediately following the headers

Question 92

What is a response body?

Answer 92

Data transmitted to an HTTP transaction

Question 93

What are headers?

Answer 93

They let the client and server pass additional info with an HTTP request. Consists of case-insensitive name followed by : then it's value

Question 94

What is JSON?

Answer 94

File format and data interchange format that uses human readable text to store and transmit data. Uses key-value pairs

Question 95

What is Javalin?

Answer 95

A lightweight REST API library

Question 96

How can I design an endpoint in Javalin?

Answer 96

app.get("/url", this::methodnamehandler);

Question 97

What is the Context object used for in Javalin?

Answer 97

Allows you to handle an http-request

Question 98

Can you explain the 3-layer controller-service-DAO architecture?

Answer 98

Controller: handles the navigation between different views Service: Stands on top of the persistence mechanissm to handle users requirements DAO: Encapsulates the details from the persistence layer and provides a crud interface for a single entity

Question 99

What is Maven?

Answer 99

Build automation tool that adds new dependencies for building and managing projects

Question 100

What file should be changed to add new Maven dependencies?

Answer 100

pom.xml

Question 101

What is the Maven lifecycle?

Answer 101

validate compile test package integration test verify install deploy

Question 102

How do I find and add a new dependency to Maven?

Answer 102

mvn install -

Question 103

What are foreign keys in SQL?

Answer 103

A field in one table that refers to the primary key in another table

Question 104

What is the referential integrity in SQL?

Answer 104

Refers to the relationship between tables. It's the logical dependency of a foreign key on a primary key

Question 105

What is a constraint in SQL?

Answer 105

Rules enforced on the data columns of a table

Question 106

What is the NOT NULL constraint?

Answer 106

The value must be filled into that field...Can't be left blank

Question 107

What is the UNIQUE constraint?

Answer 107

Makes sure the column's value is unique in the table...No duplicate values

Question 108

What does GROUP BY do?

Answer 108

Groups rows that have the same values into summary rows

Question 109

What does HAVING do?

Answer 109

Used to filter the results of a GROUP BY query based on aggregate calculations

Question 110

What is an alias in SQL?

Answer 110

Temporarily renaming a table or column for easier reading

Question 111

What is multiplicity in SQL?

Answer 111

Specifies the number of instances of a type of data in a table?

Question 112

What the different types of multiplicity?

Answer 112

one to many zero or one to one zero or one to many

Question 113

What do you need to add to have one to many multiplicity?

Answer 113

an entity instance can be related to multiple instances of the other entities

Question 114

What do you need to add to have many to many multiplicity?

Answer 114

Entity instances can be related to multiple instances of eachother

Question 115

How do you modify existing tables?

Answer 115

ALTER TABLE table

Question 116

What is normalization and why do we use it?

Answer 116

Process of taking a database design and apply a set of formal criteria and rules called normal forms. It reduces redundant data

Question 117

What characterizes 1st normal form (1nf)?

Answer 117

Rows/columns not ordered No duplicate data Row/column intersection have unique and no hidden values

Question 118

What characterizes 2nd normal form(2nf)?

Answer 118

Fullfil 1nf requirements All nonkey columns must depend on primary key Partial dependencies are removed and placed in a separate table

Question 119

What characterizes 3rd normal form(3nf)?

Answer 119

Fullfils 2nf requirements Non primary key columns shouldn't depend on other non primary key columns No transitive functional dependency

Question 120

What is a join in SQL?

Answer 120

Combines records from two or more tables in a database

Question 121

What is an inner join?

Answer 121

Returns matching rows from both tables

Question 122

What are left/right joins?

Answer 122

Returns all rows from specified side and matching rows from the other side

Question 123

What is a view in SQL?

Answer 123

Virtual tables from tables in a database

Question 124

What is REST?

Answer 124

REpresentational State Transfer making computer systems on the web communicate with each other easier

Question 125

Why do we use REST?

Answer 125

They are stateless and they separate the concerns of the client and server

Question 126

What is a resource in REST?

Answer 126

Entities that are accessed by the URL you supply

Question 127

What does it mean to be stateless?

Answer 127

Each request must contain all the information necessary to be understood by the server instead of being depending on the server remembering prior requets

Question 128

What do we need to do to make an endpoint RESTful?

Answer 128

The client request should contain all the information necessary to respond

Question 129

What is the JDK?

Answer 129

Java Development Kit that offers tools necessary to develop Java programs

Question 130

What is the JRE?

Answer 130

Java Runtime Environment provides the minimum requirements for executing Java applications. It consists of the JVM, core classes, and supporting files

Question 131

What is the JVM?

Answer 131

Java Virtual Machine that is responsible for executing code line by line

Question 132

What terminal command is used to compile a Java File?

Answer 132

JAVAC

Question 133

What is contained in Stack Memory?

Answer 133

Temporary memory allocation for variables

Question 134

What is contained in Heap Memory?

Answer 134

Long term dynamic memory. Chunk of memory available for the programmer

Question 135

What is the String Pool and does it belong to Stack or Heap Memory?

Answer 135

When creating a string it looks for a reference to that string in the pool and assigns it. It is contained in Heap Memory.

Question 136

What is garbage collection?

Answer 136

Process by which java programs perform automatic memory management

Question 137

What is UNIX?

Answer 137

Operating system developed in the 1960s which has been under constant development since

Question 138

How do i change directories in UNIX?

Answer 138

cd directoryname

Question 139

How do I view contents of my directory in UNIX?

Answer 139

ls

Question 140

What is Git?

Answer 140

Distributed version control system that tracks changes in any set of computer files

Question 141

Why do we use Git?

Answer 141

Coordinating work among programmers and seeing changes made throughout applications

Question 142

What is a commit?

Answer 142

After making changes in code you commit and set a message stating what changes were made. It saves a revision of the code to be pushed

Question 143

What is GitHub?

Answer 143

Website to push changes to code for storing and viewing

Question 144

What does pushing do?

Answer 144

Sends the commited code to some other source

Question 145

What does pulling do?

Answer 145

Retrieves previously pushed code to you local machine

Question 146

What does clone do?

Answer 146

Downloads a project form a source to your local machine

Question 147

What does branch do?

Answer 147

Creates a new branch of the main code base to work on different features of an application without affecting the main code

Question 148

What does checkout do?

Answer 148

Switches branches

Question 149

What does merge do?

Answer 149

Joins two or more development histories together

Question 150

What is a merge conflict?

Answer 150

When two or more developers change the same line or code or deletes a file one was working on and git can't automatically determine which is correct

Question 151

What are the 4 pillars of OOP?

Answer 151

Abstraction Encapsulation Inheritance Polymorphism

Question 152

What is Inheritance?

Answer 152

Subclasses extend the base class and takes on their properties and methods

Question 153

What is Polymorphism?

Answer 153

Methods with the same name taking on different forms and functions. Can be done by overriding or overloading

Question 154

What is Encapsulation?

Answer 154

Information hiding from the user and making the class attributes inaccessible from the outside classes. Use getters and setters to obtain info

Question 155

What is Abstraction?

Answer 155

Handles complexity by hiding unnecessary details from the user so they only focus on the applications main function

Question 156

What is the Object class in Java?

Answer 156

It is the Parent class of all classes in Java

Question 157

What methods does the Object class contain?

Answer 157

getClass() hashCode() wait() toString() clone() equals() finalize() notify() notifyAll()

Question 158

What are Generics in Java?

Answer 158

It means parametrized types allows all types to be a parameter to methods, classes, and interfaces

Question 159

What are interfaces in Java?

Answer 159

Abstract class that is used to group related methods with empty bodies. Uses implements instead of extends. It's an Is-A Relationship

Question 160

What does extending a class do?

Answer 160

Allows the sub classes to inherit to methods and properties of the base class

Question 161

What does implementing an interface do?

Answer 161

Achieves total abstraction and allows us to achieve multiple inheritance of a class since you can't extend multiple classes

Question 162

What is the difference between runtime and compile time polymorphism?

Answer 162

Runtime: Dynamic, Overrides methods: A method with the same name is extended/implemented overrides the base method Compile time: Static, Overloads methods: Multiple methods with the same name but different amounts or types of parameters

Question 163

What is Method Overloading?

Answer 163

Multiple methods with the same name but different types or amount of parameter values

Question 164

What is Method Overriding?

Answer 164

A method with the same name in a child class overrides the parent class method of the same name

Question 165

Can you extend multiple classes?

Answer 165

NO

Question 166

Can you implement multiple interfaces?

Answer 166

YES

Question 167

How might access modifiers help us achieve Encapsulation?

Answer 167

Having private or protected modifiers keeps data contain to the class itself

Question 168

What does the Comparable interface do?

Answer 168

Used to compare an object of the same class with an instance of that class

Question 169

What is the SDLC?

Answer 169

Software Development Life Cycle is a framework that development teams use to create a cost effective and time efficient piece of software. Agile is an example.

Question 170

What is Agile Development?

Answer 170

An approach to the software development life cycle that supports collaboration, flexibility, and iterative development. Focuses on user experience and input given to developers.

Question 171

What is a Sprint?

Answer 171

Set periods of time that team members have to complete their tasks and review what they've been working on.

Question 172

What are Ceremonies in Agile/Scrum

Answer 172

Meetings where the development team comes together to keep each other updated on their assigned tasks for projects.

Question 173

What are User Stories?

Answer 173

Features that the end user would like to see implemented in the project.

Question 174

What is Story Pointing?

Answer 174

A value assigned to user stories to help determine how much effort is needed to complete a feature.

Question 175

What is Velocity in Agile Development?

Answer 175

A way to measure the time it takes for the development team to implement user stories within a sprint. It assists the project manager in getting a realistic idea of how much progress is being made at the end of each sprint.

Question 176

What is Time Complexity?

Answer 176

An estimate of how long an algorithm will take to execute on different input sizes

Question 177

What is O(1)?

Answer 177

O(1) is Constant time: The algorithm will take the same amount of time regardless of input size

Question 178

What is O(n)?

Answer 178

O(n) is Linear time: Execution time scales directly with input size. (For-Loops)

Question 179

What is O(log n)?

Answer 179

O(log n) is Logarithmic time: Each time the size of the input doubles, the execution time increases by the same amount. (Binary search)

Question 180

What is O(n^2)?

Answer 180

O(n^2) is Quadratic time: The algorithm scales by the input sizes' square.(Nested For-Loops)

Question 181

Describe the Linear Search Algorithm and what is the Time Complexity?

Answer 181

Linear search algorithms start at the beginning of list of elements and iterates each one until it finds the target element. An example would be iterating through an array with a for loop. Time complexity is O(n): Linear time

Question 182

Describe the Binary Search Algorithm and what is the Time Complexity?

Answer 182

Binary search algorithms start at the middle of a list of elements. If the target element is the middle element the algorithm completes. If the target element is larger than the middle element, it searches to the right of the middle element and repeats the process again until the target is found. If the target element is smaller than the middle element, it searches to the left of the middle element and repeats the process again until the target is found. Time complexity is O(log n): Logarithmic time

Question 183

What is one way you could take to sort an Array?

Answer 183

There are several different algorithms to sort arrays. The simplest and most efficient is the Selection Sort: First iteration compares each value to find the smallest value in the array and swap it with the element at index 0. The next iteration would would find the smallest value again but would start at the next index value. Repeats until Array is sorted. Time complexity of O(n^2) Quadratic time because it utilizes nested for-loops.

Question 184

How does ArrayList work?

Answer 184

ArrayLists work similar to Arrays where you access elements by the index value, however they can change size has many methods to add elements (add()), modify elements (set()), and delete elements (clear()).

Question 185

How does a LinkedList work?

Answer 185

LinkedLists element's are called Nodes. LinkedLists aren't stored in a contiguous manner in memory. Each node as a pointer to the next node which is how each node finds the next in memory. Singly LinkedLists only works forward. The first Node only stores the memory location of the next Node. Doubly LinkedLists can traverse forwards and backwards as each node stores the memory location of the previous and the next Node.

Question 186

What is a Thread?

Answer 186

In Java, a thread is the smallest unit of processing that can be executed independently by the JVM. It is essentially a lightweight sub-process that runs concurrently with other threads within a program.

Question 187

Why would using threading be advantageous?

Answer 187

Can improve the performance of a program by allowing multiple threads to execute in parallel Can make the program more responsive by allowing it to continue to process user input while performing other tasks in the background Improves efficiency of time and utilization of resources because processes can run asynchronously and concurrently

Question 188

How do you create a new thread?

Answer 188

A thread is created by extending the java.lang.Thread class or implementing a runnable interface. Get an ExecutorService instance with Executors.newFixedThreadPool(int) Create a new WaitingThread with a new WaitingThread(String, int)

Question 189

What is a race condition?

Answer 189

A race condition occurs when more than one sub-processes attempt to access the same location in memory at which a particular object is stored.

Question 190

How would you prevent a race condition?

Answer 190

Race conditions can be prevented by synchronizing the sub-process/method Synchronization may be implemented by: 1: Using the synchronize keyword 2. Using Mutexes 3. Using Semaphores 4. Using a Lock Alternatively using thread safe data structures, proper encapsulation of data within a sub-process, messaging between threads, and atomic operations can prevent race conditions

Question 191

What is a Deadlock?

Answer 191

When multiple threads are attempting to access the same resource so neither actually can access it.

Question 192

What features were added to Java 5?

Answer 192

Generics Enhanced For-Loops Autoboxing/Unboxing Typesafe enums Varargs Static import Concurrent collections Copy on write compare and swap Locks

Question 193

What features were added in Java 8?

Answer 193

Lambda Expressions Streams Nashorn String.join()

Question 194

What is Reflection?

Answer 194

Java feature that allows a program to examine or "introspect" upon itself, and manipulate internal properties of the program. (getClass())

Question 195

What is a Lambda Expression?

Answer 195

Short block of code which takes in parameters and returns a value. Similar to methods but don't need a name and can be implemented in the body of a method

Question 196

What is a Functional Interface?

Answer 196

Interface with only one method (ex...Single Abstract Method)

Question 197

What are Streams?

Answer 197

Abstraction of non-mutable collection of functions applied in some order to the data. They do not store data.

Question 198

What are some operations that streams can do?

Answer 198

Intermediate Operations (Returns another stream) or Terminal Operations (triggers the execution of the stream pipeline) ForEach(): Terminal operation, loops over the stream elements Map(): Produces a new stream after applying a function to each element of the original stream Collect(): Gets elements out of the stream into and puts the values into the variable Filter(): produces a new stream with elements that pass the predicate Findfirst(): returns an optional for the first entry in the stream ToArray(): returns an array of elements from the stream FlatMap(): Helps "flatten" data structure to simplify further operations Peek(): Allows the developer to perform multiple operations on each element in a stream

Question 199

How does the Singleton Design Pattern work and why would you use it?

Answer 199

A creational design pattern that ensures that a class has only one instance, while providing a global access point to this instance. We use it because it is more memory space efficient and the single object can be used repeatedly over the client program.

Question 200

How does the Factory Design Pattern work and why would we use it?

Answer 200

A creational design pattern used to create an object without exposing the creation logic to the client. We use it to provide an approach for interface rather than implementation and provides abstraction.

Question 201

What is Logging?

Answer 201

A framework for Java to understand and debug program runtime behavior by capturing persisting important data, making it available for analysis at any point in time.

Question 202

Why would you use Logging?

Answer 202

It eases and standardizes the debugging process by providing flexibility and avoiding explicit instructions

Question 203

What is Procedure in PL/SQL?

Answer 203

Functions that will auto trigger when something happens. Procedures will hide the SQL queries to improve performance by having less information sent to the database

Question 204

What is a Trigger in PL/SQL?

Answer 204

When an event occurs and stored in the database and it's consistently called upon.

Question 205

In SQL what is an Index?

Answer 205

A table to quickly look up information from other tables that need to be searched frequently

Question 206

What is an SQL Index Advantageious?

Answer 206

It performs repetitive queries faster by storing the information into a table.

Question 207

What is the general structure of an HTML document and what are the different parts of the documents used for?

Answer 207

HTML documents are divided into 2 parts: head: Contains