Foundations

Question 1

Java Keywords

Answer 1

In the Java programming language, a keyword is any one of 52 reserved words that have a predefined meaning in the language; because of this, programmers cannot use keywords as names for variables, methods, classes, or as any other identifier. For example “public” or “class”.

Question 2

Access Modifier

Answer 2

As the name suggests access modifiers in Java helps to restrict the scope of a class, constructor, variable, method, or data member. There are four types of access modifiers available in java:

Default – No keyword required
Private
Protected
Public

Question 3

Class

Answer 3

Everything in Java is associated with classes and objects, along with its attributes and methods. For example: in real life, a car is an object. The car has attributes, such as weight and color, and methods, such as drive and brake.

A Class is like an object constructor or a “blueprint” for creating objects.

Question 4

Method

Answer 4

A collection of statements (one or more) that perform an operation.

Question 5

Main Method

Answer 5

The starting or entry point to every Java program:

public static void main(String[ ] args) {

}

Question 6

Code Block

Answer 6

A Code Block is used to define a block of code. It’s mandatory to have one in a method declaration and it’s here where we add statements to perform certain tasks.
A code block occurs with and between the curly braces:

{

}

Question 7

Statements

Answer 7

Java statements appear inside of methods and classes; they describe all activities of a Java program. Variable declarations and assignments, such as those in the previous section, are statements, as are the basic language structures like conditionals and loops.

Question 8

Expressions

Answer 8

Expressions describe values; an expression is evaluated to produce a result, to be used as part of another expression or in a statement. Method calls, object allocations, and, of course, mathematical expressions are examples of expressions.

Question 9

Variables

Answer 9

Variables are a way to store information in our computer. Variables that we define in a program can be accessed by the name we give them. The computer does the hard work of figuring out where they get stored in the computer’s Random Access Memory (RAM).

A variable, as the name suggests, can be changed, in other words, its contents are variable.

Question 10

Declaration Statment

Answer 10

Used to define a variable by indicating the data type, and the name, and optionally to set the variable to a certain value.

Question 11

Java Operators

Answer 11

Java Operators or operators perform an operation (hence the name) on a variable or value. Commong examples are:

\+ (Addition)
- (subtraction)
* (Multiplication)
/ (Division)
% (Remainder)
= (Assign value to)
== (Equivalence)
etc.

Question 12

Java Packages

Answer 12

A package is a way to organize your Java projects. Think of them as folders.

Question 13

Casting

Answer 13

Casting means to treat or convert a number from one data type to another. We put the type we want it to be in parenthesis like this (byte) (myMinByteValye/2);

Bonus: Other languages have casting, this is not just a Java thing.

Question 14

String

Answer 14

A string, is used to store a series of characters. Although it is used like a primitive data type, it is not a primitive data type, it’s actually a class, but because we use it so often, Java gives favoritism to the String class and allows us to use it the same way we use primitive data types.