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Java Examples


Java Syntax

Create a simple "Hello World" program

Syntax Explained


Java Comments

Single-line comment before a line of code
Single-line comment at the end of a line of code
Multi-line comment

Comments Explained


Java Variables

Create a string variable
Create an integer variable
Create a variable without assigning the value, and assign the value later
Combine text and a variable on display
Add a variable to another variable
Declare many variables of the same type with a comma-separated list

Variables Explained


Java Data Types

A demonstration of different data types in Java
Create a byte type
Create a short type
Create an int type
Create a long type
Create a float type
Create a double type
Create a boolean type
Create a char type
Create a String type

Data Types Explained


Java Operators

Addition operator
Subtraction operator
Multiplication operator
Division operator
Modulus operator
Increment operator
Decrement operator
Assignment operator
Comparison operator
Logical operator

Operators Explained


Java Strings

Create a string
Quotes inside a string
Find the length of a string
Using methods to convert strings to uppercase and lowercase
Finding a string in a string
String concatenation
If you add a number and a string, the result will be a string concatenation

Strings Explained


Java Math

Math.max(x,y) - return the highest value of x and y
Math.min(x,y) - return the lowest value of x and y
Math.sqrt(x) - return the square root of x
Math.abs(x) - return the absolute (positive) value of x
Math.random() - return a random number between 0 and 1

Math Explained


Java Booleans

Create a boolean type
Find out if an expression is true or false
Use the "equal to" operator to evaluate a boolean expression

Booleans Explained


Java If...Else (Conditions)

The if statement
The else statement
The else if statement

If...Else Explained


Java Switch

The switch statement
The switch statement with a default keyword

Switch Explained


Java Loops

While loop
Do while loop
For loop
For-each loop
Break a loop
Continue a loop

Loops Explained


Java Arrays

Create and access an array
Change an array element
Find the length of an array
Access an array
Loop through an array
Loop through an array with for-each
Multidimensional array
Loop through a multidimensional array

Arrays Explained


Java Exceptions (Try...Catch)

The try...catch statement
The finally statement
The throw statement

Exceptions Explained


Java Methods

Create and call a method
Call a method multiple times
Method with parameters
Return value
A method with if...else

Methods Explained


Java Classes and Objects

Create a class and an object of a class
Create multiple objects of a class
Accessing class attributes (variables)
Modify attributes
Override existing attribute values
Multiple attributes
Create a class method
Method with parameters
Access class methods with an object
Create a class constructor
Constructor with parameters

Classes and Objects Explained


Java Modifiers

Public class
Default class
Public attributes
Private attributes
Default attributes
Protected attributes
Final class
Abstract class with abstract methods

Modifiers Explained


Java Encapsulation

Java encapsulation (getters and setters)

Encapsulation Explained


Java Packages

Import a class from the Java API
Import a package from the Java API
Create a package

Packages Explained


Java Inheritance

Java inheritance (extends)
Java polymorphism

Inheritance Explained


Java Interfaces

Java interface (implements)
Multiple interfaces

Interfaces Explained


Java Enums

Create an enum with a group of constants
An enum inside a class
An enum in a switch statement
Loop through an enum

Enums Explained


Java User Input

Read user input

User Input Explained


Java Dates

Display current date
Display current time
Display current date and time
Formatting date and time

Dates Explained


Java ArrayList

Create an ArrayList
Access an item in an ArrayList
Remove an item from an ArrayList
Remove all items from an ArrayList
Get the size of an ArrayList
Loop through an ArrayList
Loop through an ArrayList with for-each
Create an ArrayList that should store numbers (integers)

ArrayList Explained


Java HashMap

Create a HashMap
Access an item in a HashMap
Remove an item from a HashMap
Remove all items from a HashMap
Get the size of a HashMap
Loop through a HashMap
Create a HashMap that should store String keys and Integer values

HashMap Explained


Java Files

Create a file
Get file information
Write to a file
Read a file

Files Explained