Variables and DataTypes

Question 1

What is the relationship between Java and JavaScript?

Answer 1

There is no relationship

Question 2

Source Code

Answer 2

Code created by a programmer and saved as a .java file

Question 3

Byte Code

Answer 3

Is a compiled code that can be read by the JVM independent of the Operating System (Windows, Mac OS, Linux, etc.). Stored in .class files

Question 4

Machine Code

Answer 4

Is a compiled code that can be read by a specific operating system. Created by the JVM when running.

Question 5

Java Architecture

Answer 5

A programmer writes Source Code in .java files --->
javac compiles the source code into Byte Code in .class files --->
Java Virtual Machine (JVM) interprets Byte Code into Machine Code that can be understood by the computer’s operating system

Question 6

Java Version Check

Answer 6

In terminal: java -version

Question 7

Java JDK (Java Development Kit) Version Check

Answer 7

In terminal: javac -version

Question 8

Java Runtime Environment (JRE)

Answer 8

Allows execution of Java applications.
Installed by default on most OSs
Contains the JVM
Does not contain libraries and tools for development
Used by home users

Question 9

Java Development Kit (JDK)

Answer 9

Includes development library and tools
Includes the javac compiler
Includes the JRE and JVM
Used only by developers

Question 10

Workspace

Answer 10

A folder or a directory on the harddrive where Eclipse stores preferences, configurations, and project information about the projects added to the workspace.

Question 11

Eclipse is an IDE (Integrated Development Environment)

Answer 11

Organizes code into projects and workspaces
Provides immediate feedback on syntax errors
Assists in code with Intellisense
Allows us to suspend a program and step through using a Debugger

Question 12

Variables

Answer 12

A storage container paired with a name. It holds some known or unknown amount of information, called the value.

Question 13

Parts of variables

Answer 13

Data Type
Name
Value

Question 14

Data Type

Answer 14

Defines the type of data stored in a variable and how it’s represented

Question 15

Name

Answer 15

A label that defines what the variable represents

Question 16

Declaration

Answer 16

Defines the Data Type and Name

Question 17

Assignment

Answer 17

Sets a value

Question 18

Casting

Answer 18

Allows us to tell Java to treat a variable as a different data type, provided they both hold the same type of data.

Question 19

Widening

Answer 19

Casting from a smaller data type into a larger data type. For example int to long.
Casting is implicit
int x = 10;
long y = x;

Question 20

Narrowing

Answer 20

Casting from a larger data type to a smaller one. For example, long to int or double to int
Narrowing is explicit
long x= 10;
int y = (int) x;
Explicit casting puts the data type beside the value being cast in parenthesis

Question 21

Truncation

Answer 21

Truncation is when we go from a larger to smaller data type and lose data in the process.
25.782 - Truncated to a whole number - 25

Question 22

Integrated development environment (IDE)

Answer 22

Is a software application that provides comprehensive facilities to computer programmers for software development. Normally consists of at least a source code editor, build automation tools, and a debugger.