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varargs in Java

July 3, 2012 By j2eereference 1 Comment

Variable arguments(Varargs)

Varargs is Variable arguments, this feature has been added in Java 5. This is the feature that enables methods to receive variable numbers of arguments

Syntax for Varargs:

public void displayVar(int count, String… args) { }

The Varargs includes three dots … which is called ellipses.

The three periods after the parameter’s type indicate that the argument may be passed as an array .

Conditions for using Varargs:

  • Varargs should come last in the parameter list.

int sum(int…a,floatc) // will result in compile time error as Varargs should be last argument.

  • Datatype of Varargs should be same.
  • Only one set of Varargs is allowed .

int sum(int…a,int…b) // compile time error, as there is only one Variable argument is allowed.

Example for Varargs:

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package com.j2eereference.varArgs;
 
public class VarargsExample {
 
        public static void Vardisplay(int id, String... Varargs) {
                System.out.println("Author Id is "+id);
        for(String arg: Varargs) {       
            System.out.println(arg);
        }
        System.out.println("******************");
    }
 
    public static void main(String args[]) {
        Vardisplay(1, "Name 1 ", "25");
        Vardisplay(2, "Name 2 ", "26", "India");
    }
 
}

 Output

Author Id is 1
Name 1
25
******************
Author Id is 2
Name 2
26
India
******************

Varargs Overloading :

We Can do Overloading in Varargs.

Consider the example in this

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package com.j2eereference.varArgs;
public class Overloading {
          static void vardisplay(int...vargs) {
          System.out.println("Inside method with int Varargs");
          System.out.println("Length of arguments: " +vargs.length);
           for (int arg : vargs)
             {
              System.out.println("Value "+arg);
             }
           }
 
          static void vardisplay(String... vargs) {
            System.out.println("Inside method with String varargs");
            System.out.println("Length of arguments: " +vargs.length);
            for (String arg : vargs)
              System.out.println(arg);
        }
          public static void main(String args[]) {
            vardisplay(1, 2); // will compile and run
           //vardisplay(); // Give compile time error.
            vardisplay("Delhi","Calcutta", "Banglore"); // will compile and run
 
          }
   }

Output

Inside method with int Varargs
Length of arguments: 2
Value 1
Value 2
Inside method with String varargs
Length of arguments: 3
Delhi
Calcutta
Banglore

How To covert Varargs into array.

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package com.j2eereference.varargs;
 
public class VarargsDemo
{
public static void varDisplay(int...args)
{
int[] vartoarray=args;
System.out.println("Elements in array is:");
for (int i = 0; i < args.length; i++) {
int arr=vartoarray[i];
System.out.println(arr);
    }
}
 
public static void main(String[] args) {
varDisplay(100,101,102,103,104,105,106);
  }
 
}

Output is:Elements in array is:

100

101

102

103

104

105

106

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Filed Under: Core Java

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    April 28, 2015 at 12:09 am

    […] the second case we are passing parameter through varargs , Click here to know more about varargs in […]

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