Table of Contents

• One Dimensional Array
  • Declaring Array
  • Allocting Memory to Array
  • Accessing Array Elements
  • Initializing Array
  • Length of Array
• Multi Dimensional Array
• Creating 3 Dimensional Array

Introduction

Arrays are used to store a group of values of the same data type. So a single variable can be used to refer to the group of values. Arrays can store data of any data type and can have one or more dimensions as explained below.

1. One-Dimensional Array

A one-dimensional array is essentially a list of values referred to by a common name.

int myArray[]; // creates myArray to store int values

myArray = new int[10]; // creates array of size 10

int myArray[] = new int[10]; //creates myArray with size 10

myArray[3] = 5; // element at index 3, i.e.4th element will be assigned 5

int value = myArray[2]; 
// value at index 2 i.e. 3rd position is assigned to the variable value

int myArray[] = {2,4,6,8,10}; 
//creates new array of size 5 with specified values

int myArray[] = {2,4,6,8,10};
int size = myArray.length; // size will be 5

2. Multi-Dimensional Arrays

Multidimensional arrays are basically arrays of arrays. They are used to store data in tabular form. Each additional index needs to be specified using additional square brackets.

int myArray[][] = new int[4][6];

int val = myArray[2][4]; 
// a will be assigned the element at row index 2 and column index 4

3. Creating and Using a 3-Dimensional Array

Similarly, you can create a 3-dimensional array as follows:

int myArray[][][] = new int [2][3][4];
myArray[1][0][3] = 5;

This code declares a 3-dimensional array with 2,3,4 as the dimensions. It sets the element at position 1,0,3 to 5.

Conclusion

So this article covers what arrays are and how you can use them. It also walks you through multi-dimensional arrays.

The post Java Tutorial #3 – Java Arrays appeared first on Automation Dojos.

Table of Contents

• Introduction
• 1. Assignment Operator
• 2. Arithmetic Operators
• 3. Compound Operators
• 4. Increment & Decrement Operators
• 5. Relational Operators
• 6. Logical Operators

Introduction

Operators are an essential part of any programming language. In-fact it is not possible not to write a decent piece of code without making use of ‘Operators’. Java operators can be categorized mainly into arithmetic, relational and logical operators. In addition, there is a special assignment operator that is used to assign values to variables. Each of these is covered in a separate section below.

1. Assignment Operator

The “=” sign is known as the assignment operator.  It assigns whatever is to its right to the variable on its left. The variable type must be compatible with the value being assigned. The following code demonstrates this:

int a = 10; //assigns the value 10 to the variable a

int b = 5+8; // assigns the value 13 to the variable b

2. Arithmetic Operators

Arithmetic operators are those that are used in ordinary mathematics, that is addition, subtraction, multiplication and division. These can only be applied to numerical operands. The Arithmetic operators can be further broken down into Basic Operators, Compound Assignment Operators and Increment/Decrement operators.

3. Compound Assignment

Java provides special operators which can be used to combine an operation with an assignment.  These are known as compound assignment operators. The compound operators are just shortcut operators which can be used when you want to change the value of a particular variable. Java supports compound assignment operators for each of the arithmetic operators as listed below:

4. Increment & Decrement Operators

Java provides two additional operators known as increment and decrement operators. These basically increment or decrement the variable on which they are invoked.

Both operators come in two variants, prefix and postfix. In the prefix form the operator precedes the operand and the operation is performed before the assignment. In the postfix form, the operator succeeds the operand and the operation is performed after the assignment. The following code demonstrates this:

int i = 5;
//postfix form, will print i, then increment, so will output 5
System.out.println(i++); 
int j = 10;
//prefix form, will decrement j first then print it, so will output 9
System.out.println(--j);

5. Relational Operators

Relational operators are used to determine the relationship between operands. They return a boolean value. Java has the following relationship operators:

6. Logical Operators

Logical operators operate on boolean values and are used to combine relational comparisons. Java has the following logical operators:

Logical operators can be used to combine relational comparisons as follows:

int a=30, b=20, c=10;
if(a > b && b > c){
// do something
}

The post Java Tutorial #2 – Operators in Java appeared first on Automation Dojos.