Arrays.fill() in Java with Examples

java.util.Arrays.fill() method is in java.util.Arrays class. This method assigns the specified data type value to each element of the specified range of the specified array.

Syntax:
// Makes all elements of a[] equal to "val"
public static void fill(int[] a, int val)

// Makes elements from from_Index (inclusive) to to_Index
// (exclusive) equal to "val"
public static void fill(int[] a, int from_Index, int to_Index, int val)

This method doesn't return any value.
Exceptions it Throws:
IllegalArgumentException - if from_Index > to_Index
ArrayIndexOutOfBoundsException - if from_Index  a.length

Examples:

We can fill entire array.

// Java program to fill a subarray of given array
import java.util.Arrays;
  
public class Main
{
    public static void main(String[] args)
    {
        int ar[] = {2, 2, 1, 8, 3, 2, 2, 4, 2};
  
        // To fill complete array with a particular
        // value
        Arrays.fill(ar, 10);
        System.out.println("Array completely filled" +
                  " with 10\n" + Arrays.toString(ar));
    }
}

Output:

Array completely filled with 10
[10, 10, 10, 10, 10, 10, 10, 10, 10]

We can fill part of array.



// Java program to fill a subarray array with 
// given value.
import java.util.Arrays;
  
public class Main
{
    public static void main(String[] args)
    {
        int ar[] = {2, 2, 2, 2, 2, 2, 2, 2, 2};
  
        // Fill from index 1 to index 4.
        Arrays.fill(ar, 1, 5, 10);
     
        System.out.println(Arrays.toString(ar));
    }
}

Output:

[2, 10, 10, 10, 10, 2, 2, 2, 2]

We can fill a multidimensional array
We can use a loop to fill a multidimensional array.

// Java program to fill a multidimensional array with 
// given value.
import java.util.Arrays;
  
public class Main
{
    public static void main(String[] args)
    {
        int [][]ar = new int [3][4];
  
        // Fill each row with 10. 
        for (int[] row : ar)
            Arrays.fill(row, 10);
     
        System.out.println(Arrays.deepToString(ar));
    }
}

Output:

[[10, 10, 10, 10], [10, 10, 10, 10], [10, 10, 10, 10]]

This article is contributed by Mohit Gupta. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.



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