Array set() method in Java

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 :

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    // 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);
            }
        }
    }

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    Output:

    Befor Set : GeeksisGeeks
    After Set : GeeksforGeeks
    

    Program 2 : to demonstrate java.lang.NullPointerException

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    // 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);
            }
        }
    }

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    Output:

    Exception : java.lang.NullPointerException
    

    Program 3 : to demonstrate java.lang.ArrayIndexOutOfBoundsException

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    // 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);
            }
        }
    }

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    Output:

    Exception : java.lang.ArrayIndexOutOfBoundsException
    

    Program 4 : to demonstrate java.lang.IllegalArgumentException

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    // 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);
            }
        }
    }

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    Output:

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


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