Arrays.fill(int[], int, int, int) in Java

Arrays.fill(int[], int, int, int): This method is available in java.util.Arrays class of Java.

Syntax:

void java.util.Arrays.fill(int[] a, int fromIndex, int toIndex, int val)

This method takes four arguments one of type int array and the rest three are of type int as its parameters. This method assigns the specified int value to each element of the specified range of the specified array of ints.

Parameters: Four parameters are required for this method.

a: the array to be filled.

fromIndex: the index of the first element (inclusive) to be filled with the specified value.

toIndex: the index of the last element (exclusive) to be filled with the specified value.

val: the value to be stored in all elements of the array.

Throws:

1. IllegalArgumentException - if fromIndex > toIndex.

2. ArrayIndexOutOfBoundsException - if fromIndex < 0 or toIndex > a.length

Approach 1: When no exceptions

Java

import java.util.Arrays;

public class Arraysfillintrange {
    public static void main(String[] args) {

        int a[] = new int[5];

        int val = 10;

        int fromIndex = 0, toIndex = 2;
        Arrays.fill(a, fromIndex, toIndex, val);

        System.out.println(Arrays.toString(a));
    }
}

Output:

[10, 10, 0, 0, 0]

Approach 2: IllegalArgumentException

Java

import java.util.Arrays;

public class Arraysfillintrange {
    public static void main(String[] args) {

        int a[] = new int[5];

        int val = 10;

        int fromIndex = 3, toIndex = 2;
        Arrays.fill(a, fromIndex, toIndex, val);

        System.out.println(Arrays.toString(a));
    }
}

Output:

Exception in thread "main" java.lang.IllegalArgumentException: fromIndex(3) > toIndex(2)
	at java.base/java.util.Arrays.rangeCheck(Arrays.java:718)
	at java.base/java.util.Arrays.fill(Arrays.java:3202)
	

Approach 3: ArrayIndexOutOfBoundsException

Java

import java.util.Arrays;

public class Arraysfillintrange {
    public static void main(String[] args) {

        int a[] = new int[5];

        int val = 10;

        int fromIndex = -1, toIndex = 2;
        Arrays.fill(a, fromIndex, toIndex, val);

        System.out.println(Arrays.toString(a));
    }
}

Output:

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: Array index out of range: -1
	at java.base/java.util.Arrays.rangeCheck(Arrays.java:722)
	at java.base/java.util.Arrays.fill(Arrays.java:3202)