Java Arrays Fill

By using the Arrays.fill() method, we can either fill a complete array or can fill some part of it. Arrays.fill() method is also capable of filling both the 2D and the 3D Arrays.

Arrays fill() method has the following syntax:

Here,

The arr parameter defines an array to be filled.
The formIndex parameter defines the index of the first element to be filled with the given value.
The toIndex parameter defines the index of the last index to be filled with the given value.
The val parameter defines the value to be stored in all elements of the given array.

Let's take some examples to understand how we can use the Arrays.fill() method for filling array.

Fill entire 1-D Array

ArraysFillExample1.java

// import required classes and packages
import java.util.Arrays;
import java.util.Scanner;  
// create ArraysFillExample1 to fill sub-array to given array
public class ArraysFillExample1
{
	//main() method start
    public static void main(String[] args)
    {
        int size, ele;  
		Scanner sc = new Scanner(System.in);  
		System.out.print("Enter the size of the array: ");  
		size = sc.nextInt();  
		//creates an array of size 100
		int[] array = new int[100];  
		System.out.println("Enter the elements in the array: ");  
		for(int i = 0; i < size; i++)  
		{  
			array[i] = sc.nextInt();  
		}
		System.out.print("Enter the element which you want to fill in the array: ");  
		ele = sc.nextInt();
        // fill complete array with ele
        Arrays.fill(array, ele);
		
        System.out.println("After filling" +ele+ " in complete array:\n" + Arrays.toString(array));
    }
}

Output:

Fill some part of 1-D Array

ArraysFillExample2.java

// import required classes and packages
import java.util.Arrays;
import java.util.Scanner;  
// create ArraysFillExample2 to fill some part of the array with the given value
public class ArraysFillExample2
{
	//main() method start
    public static void main(String[] args)
    {
        int size, ele, index1, index2;  
		Scanner sc = new Scanner(System.in);  
		System.out.print("Enter the size of the array: ");  
		size = sc.nextInt();  
		//creates an array of size 100
		int[] array = new int[100];  
		System.out.println("Enter the elements in the array: ");  
		for(int i = 0; i < size; i++)  
		{  
			array[i] = sc.nextInt();  
		}
		System.out.print("Enter the element which you want to fill in the array: ");  
		ele = sc.nextInt();
	System.out.print("From which index you want to fill "+ele+" in the array: ");  
		index1 = sc.nextInt();
		System.out.print("To which index you want to fill "+ele+" in the array: ");  
		index2 = sc.nextInt();
        // fill complete array with ele
        Arrays.fill(array, index1, index2, ele);
		
        System.out.println("After filling" +ele+ " in the array:\n" + Arrays.toString(array));
    }
}

Output:

Fill multidimensional array (2D Array)

Just like a single-dimensional array, we can also fill the multidimensional array by using the Arrays.fill() method. In order to fill a multidimensional array, we use the for loop to fill each row of the multidimensional array.

Let's take an example to understand how we can fill a multidimensional array using the Arrays.fill() method.

ArraysFillExample3.java

// import required classes and packages
package javaTpoint.MicrosoftJava;
import java.util.Arrays;
import java.util.Scanner;  
// create ArraysFillExample3 to fill the multidimensional array with the given value
public class ArraysFillExample3
{
	//main() method start
    public static void main(String[] args)
    {
        int ele;  
        // create scanner class object
        Scanner sc = new Scanner(System.in);  
		System.out.print("Enter the size of the array: \n");  
		System.out.print("Enter size of row : \n");
		int rows = sc.nextInt();
		System.out.print("Enter size of column : \n");
	    int columns = sc.nextInt();  
	    // create an array of size row*column
	    int twoDArray[][] = new int[rows][columns];
		System.out.println("Enter the elements in the array: \n");  
		for(int i = 0; i < rows; i++)
        {            
           for(int j = 0; j < columns; j++)
           {
        	   System.out.println("Enter element ["+i+"]["+j+"]");
        	   twoDArray[i][j] = sc.nextInt();
           }
}		
		System.out.print("Enter the element which you want to fill in the array: \n\n");  
		ele = sc.nextInt();
		System.out.println("Multi-dimensional array after inserting elements: \n\n");  
		System.out.println(Arrays.deepToString(twoDArray));
		// fill complete array with ele 
		for (int[] row : twoDArray)
            Arrays.fill(row, ele);
        System.out.println("After filling" +ele+ " in the array:\n\n" + Arrays.deepToString(twoDArray));
        sc.close();
    }
}

Output:

ArraysFillExample4.java

// import required classes and packages
package javaTpoint.MicrosoftJava;
import java.util.Arrays;
import java.util.Scanner;  
// create ArraysFillExample4 to fill 3D array with the given value
public class ArraysFillExample4
{
	//main() method start
    public static void main(String[] args)
    {
        int ele;  
        // create scanner class object
        Scanner sc = new Scanner(System.in);  
		System.out.print("Enter the size of the array: \n");  
		System.out.print("x : ");
		int x = sc.nextInt();
		System.out.print("y : ");
	    int y = sc.nextInt();  
	    System.out.print("z : ");
	    int z = sc.nextInt(); 
	    // create an array of size row*column
	    int threeDArray[][][] = new int[x][y][z];
		System.out.println("Enter the elements in the array: ");  
		for(int i=0; i < threeDArray.length; i++){
			for(int j=0; j < threeDArray[i].length; j++){
				for(int k=0; k < threeDArray[i][j].length; k++){
					   System.out.println("Enter element ["+i+"]["+j+"]["+k+"]");
					   threeDArray[i][j][k] = sc.nextInt();
		        }
			}
		}
		System.out.print("Enter the element which you want to fill in the array: \n\n");  
		ele = sc.nextInt();
		System.out.println("3D array after inserting elements: \n\n");  
		System.out.println(Arrays.deepToString(threeDArray));
		// fill complete array with ele
		for (int[][] newRow : threeDArray) {
            for (int[] newRowColumn : newRow) {
                Arrays.fill(newRowColumn, ele);
            }
        }
        System.out.println("After filling" +ele+ " in the array:\n\n" + Arrays.deepToString(threeDArray));
        sc.close();
    }
}

Output: