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

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

Syntax:

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

This method takes four arguments one of the type char arrays, and the other two are of type int, and the other one of type char as its parameters. This method assigns the specified char value to each element of the specified range of the specified array of chars.

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.

Returns: NA

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 Arraysfillcharrange {
    public static void main(String[] args) {

        char a[] = new char[5];

        char val = 'a';

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

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

Output:

[a, a, , , ]

Approach 2: IllegalArgumentException 

Java

import java.util.Arrays;

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

        char a[] = new char[5];

        char val = 'a';

        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:3272)
	

Approach 3: ArrayIndexOutOfBoundsException 

Java

import java.util.Arrays;

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

        char a[] = new char[5];

        char val = 'a';

        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:3272)