Array set() method in Java - GeeksforGeeks

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 classimport 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 classimport 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 classimport 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 classimport 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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Below programs illustrate the Array.set() method:
Program 1 :
// Java code to demonstrate set() method of Array classimport 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);        }    }}
Befor Set : GeeksisGeeks
After Set : GeeksforGeeks

Program 2 : to demonstrate java.lang.NullPointerException
// Java code to demonstrate set() method of Array classimport 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);        }    }}
Exception : java.lang.NullPointerException

Program 3 : to demonstrate java.lang.ArrayIndexOutOfBoundsException
// Java code to demonstrate set() method of Array classimport 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);        }    }}
Exception : java.lang.ArrayIndexOutOfBoundsException

Program 4 : to demonstrate java.lang.IllegalArgumentException
// Java code to demonstrate set() method of Array classimport 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);        }    }}
Exception : java.lang.IllegalArgumentException: Argument is not an array

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