Java Array

Java Array

ormally, array is a collection of similar type of elements that have contiguous memory location.

Java array is an object the contains elements of similar data type. It is a data structure where we store similar elements. We can store only fixed set of elements in a java array.

Array in java is index based, first element of the array is stored at 0 index.

 

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

Example of single dimensional java array

Let's see the simple example of java array, where we are going to declare, instantiate, initialize and traverse an 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.println(a[i]);

}

}

2. another example:

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]);

}

}

Passing Array to method in java

class TestarrayPassing

{

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[]={33,1,4,5};

min(a);//passing array to method

}

}

Multidimensional array in java

Example of Multidimensional java array

Let's see the simple example to declare, instantiate, initialize and print the 2Dimensional array.

class TestarrayMultiDimension

{

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();

}

}

}

What is the class name of java array?

In java, array is an object. For array object, an proxy class is created whose name can be obtained by getClass().getName() method on the object.

class TestarrayClassName

{

public static void main(String args[])

{

int arr[]={4,4,5};

Class c=arr.getClass();

String name=c.getName();

System.out.println(name);

}

}

Copying a java array

Syntax of arraycopy method

public static void arraycopy(Object src, int srcPos,Object dest, int destPos, int length)

Example of arraycopy method

class TestArrayCopy {

    public static void main(String[] args)

{

        char[] copyFrom = { 'd', 'e', 'c', 'a', 'f', 'f', 'e', 'i', 'n', 'a', 't', 'e', 'd' };

        char[] copyTo = new char[7];

        System.arraycopy(copyFrom, 2, copyTo, 0, 7);

        System.out.println(new String(copyTo));

    }

}

Addition of 2 matrices in java

class TestarrayAdd

{

public static void main(String args[])

{

//creating two matrices

int a[][]={{1,3,4},{3,4,5}};

int b[][]={{1,3,4},{3,4,5}};

//creating another matrix to store the sum of two matrices

int c[][]=new int[2][3];

//adding and printing addition of 2 matrices

for(int i=0;i<2;i++)

{

for(int j=0;j<3;j++)

{

c[i][j]=a[i][j]+b[i][j];

System.out.print(c[i][j]+" ");

}

System.out.println();//new line

}

}

}