The array is a collection similar data type. 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.
Creating Arrays:
dataType[] arrayRefVar;
arrayRefVar = new dataType[arraySize];
or
dataType[] arrayRefVar = {value0, value1, ..., valuen};
Example -: double[ ] myList = new double[10];
Types of Array in java
There are two types of array.
- Single Dimensional Array
- Multidimensional Array
Example of Single Dimensional array
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.print(a[i]+ " ");
}
Output-: 10 20 70 40 50
Multidimensional array in java
Declare of multidimensional array: dataType[][] arrayRefVar; (or)
dataType [][]arrayRefVar; (or)
dataType arrayRefVar[][]; (or)
dataType []arrayRefVar[];
Example-: int[][] arr=new int[3][3]; //3 row and 3 column
Initialized multidimensional array
arr[0][0]=1;
arr[0][1]=2;
arr[0][2]=3;
arr[1][0]=4;
arr[1][1]=5;
arr[1][2]=6;
arr[2][0]=7;
arr[2][1]=8;
arr[2][2]=9;
Example of multidimensional array
class Sample {
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();
}
}
Example of the array using for loop
public class Sample {
public static void main(String[] args) {
double[] myList = {1.9, 2.9, 3.4, 3.5};
// Print all the array elements
for (double element: myList) {
System.out.println(element);
}
}
}
Output-:
Advantage of Java Array
Disadvantage of Java Array
1.9
2.9
3.4
3.5
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.
Size Limit: We can store the 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.