Array set() method in Java

Last Updated : 30 Nov, 2018

The java.lang.reflect.Array.set() is an inbuilt method in Java and is used to set a specified value to a specified index of a given object array.

Syntax

Array.set(Object []array, int index, Object value)

Parameter :

array : This is an array of type Object which is to be updated.
index : This is the index of the array which is to be updated.
value : This is the value that is to be set at the given index of the given array

Return type : This is a void type method this doesn’t returns any value. The update reflects upon the Object array passed as the argument.

Exception : This method throws following exception.

NullPointerException – when the array is null.
IllegalArgumentException – when the given object array is not an Array.

ArrayIndexOutOfBoundsException – if the given index is not in the range of the size of the array.

Below programs illustrate the Array.set() method:

Program 1 :

// Java code to demonstrate set() method of Array class
import java.lang.reflect.Array;
public class GfG {
    // main method
    public static void main(String[] args)
    {
  
        // Declaring and defining a String array
        String s[] = { "Geeks", "is", "Geeks" };
  
        System.out.print("Befor Set : ");
        // printing the array
        for (String x : s) {
            System.out.print(x);
        }
  
        // set method of class Array
        Array.set(s, 1, "for");
  
        System.out.print("\nAfter Set : ");
        // printing array
        for (String x : s) {
            System.out.print(x);
        }
    }
}

Output:

Befor Set : GeeksisGeeks
After Set : GeeksforGeeks

Program 2 : to demonstrate java.lang.NullPointerException

// Java code to demonstrate set() method of Array class
import java.lang.reflect.Array;
public class GfG {
    // main method
    public static void main(String[] args)
    {
  
        // Declaring and defining a String array
        String s[] = null;
  
        try {
            // set method of class Array
            Array.set(s, 1, "for");
        }
        catch (Exception e) {
            System.out.println("Exception : " + e);
        }
    }
}

Output:

Exception : java.lang.NullPointerException

Program 3 : to demonstrate java.lang.ArrayIndexOutOfBoundsException

// Java code to demonstrate set() method of Array class
import java.lang.reflect.Array;
public class GfG {
    // main method
    public static void main(String[] args)
    {
  
        // Declaring and defining a String array
        String s[] = { "Geeks", "for", "Geeks" };
  
        try {
            // set method of class Array
            Array.set(s, 4, "for");
        }
        catch (Exception e) {
            System.out.println("Exception : " + e);
        }
    }
}

Output:

Exception : java.lang.ArrayIndexOutOfBoundsException

Program 4 : to demonstrate java.lang.IllegalArgumentException

// Java code to demonstrate set() method of Array class
import java.lang.reflect.Array;
public class GfG {
    // main method
    public static void main(String[] args)
    {
  
        // Declaring and defining a String array
        String s = "GeeksforGeeks";
  
        try {
            // set method of class Array
            Array.set(s, 4, "for");
        }
        catch (Exception e) {
            System.out.println("Exception : " + e);
        }
    }
}

Output:

Exception : java.lang.IllegalArgumentException: Argument is not an array

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