Arrays in Java allow storing a fixed number of elements of the same type. There are two types of arrays: single dimensional arrays which store elements in a single list, and multidimensional arrays which store elements in a table-like structure with multiple rows and columns. Arrays provide fast access to elements via indexes but have a fixed size. They are commonly used to organize related data in Java programs.

1. ARRAYS in JAVA
P NAGARAJU
Asst. Professor
Dept. of CSE

2. Introduction
 Normally, array is a collection of similar type of elements that have contiguous
memory location.
 Java provides a data structure, the array, which stores a fixed-size sequential
collection of elements of the same type.
 An array is used to store a collection of data, but it is often more useful to think of an
array as a collection of variables of the same type.
 Array in java is index based, first element of the array is stored at 0 index.

3. Advantage of Java Array
Code Optimization: It makes the code optimized, we can retrieve or sort the
data easily.
Random access: We can get any data located at any index position.
Disadvantage of Java Array
Size Limit: We can store only fixed size of elements in the array. It doesn't
grow its size at runtime. To solve this problem, collection framework is used
in java.
Types of Array in java
There are two types of array.
 Single Dimensional Array
 Multidimensional Array

4. Single Dimensional Array in java
Declaring Array Variables:
Syntax
dataType[] arrayRefVar; // preferred way.
Or
dataType arrayRefVar[]; // works but not preferred way.
Creating Arrays:
Syntax:
arrayRefVar = new dataType[arraySize];
The above statement does two things:
• It creates an array using new dataType[arraySize];
• It assigns the reference of the newly created array to the variable arrayRefVar.

5. Cont….
 Declaring an array variable, creating an array, and assigning the reference of the
array to the variable can be combined in one statement, as shown below:
dataType[] arrayRefVar = new dataType[arraySize];
Alternatively you can create arrays as follows:
dataType[] arrayRefVar = {value0, value1, ..., valuek};
Example:
class Testarray{
public static void main(String args[]){
int a[]=new int[5];//declaration and instantiation
a[0]=10;//initialization
a[1]=20;
a[2]=70;
a[3]=40;
a[4]=50;
//printing array
for(int i=0;i<a.length;i++)//length is the property of array
System.out.println(a[i]);
}}

6. Example 2:
class Testarray1{
public static void main(String args[]){
int a[]={33,3,4,5};//declaration, instantiation and initialization
//printing array
for(int i=0;i<a.length;i++)//length is the property of array
System.out.println(a[i]);
}}
Output:33
3
4
5

7. public class TestArray
{
public static void main(String[] args)
{
double[] myList = {1.9, 2.9, 3.4, 3.5}; // Print all the array elements
for (int i = 0; i < myList.length; i++)
{
System.out.println(myList[i] + " ");
}
// Summing all elements
double total = 0;
for (int i = 0; i < myList.length; i++)
{
total += myList[i];
}
System.out.println("Total is " + total);
// Finding the largest element
double max = myList[0];
for (int i = 1; i < myList.length; i++)
{
if (myList[i] > max)
max = myList[i];
}
System.out.println("Max is " + max); } }

8. Passing Array to method in java
 We can pass the java array to method so that we can reuse the same logic on any
array.
Example:
class Testarray2{
static void min(int arr[]){
int min=arr[0];
for(int i=1;i<arr.length;i++)
if(min>arr[i])
min=arr[i];
System.out.println(min);
}
public static void main(String args[]){
int a[]={33,3,4,5};
min(a);//passing array to method
}}

9. Multidimensional array in java
 Data is stored in row and column based index (also known as matrix form).
Syntax to Declare Multidimensional Array in java
dataType[][] arrayRefVar;
(or)
dataType arrayRefVar[][];
Example to instantiate Multidimensional Array in java
int[][] arr=new int[3][3];//3 row and 3 column

10. Example:
class Testarray3{
public static void main(String args[]){
//declaring and initializing 2D array
int arr[][]={{1,2,3},{2,4,5},{4,4,5}};
//printing 2D array
for(int i=0;i<3;i++){
for(int j=0;j<3;j++){
System.out.print(arr[i][j]+" ");
}
System.out.println();
}
}}