Confused in console please help

[Rajat kumar jain]

Hello all please help me in one of my doubt

actually i was writing a program in which a program has to take 3 numbers from the user and if i will not enter the third number and just press enter key then it should multiply first two numbers else it should multiply all the three numbers and show the result.
Now the problem is that
i use following statement
DataInputStream dis=new DataInputStream(System.in);
String r=dis.readLine();

now the problem is that if i dont write anything on the console and simply press enter then what would it consider it whether it will consider it as null string(r==null) or anything else as in the following code it always excecutes if statement please reply asap guys

import java.util.*;
import java.io.*;
class Tests
{
	public static void main(String args[])throws Exception
	{
		System.out.println("enter the first number");
		Scanner sc1=new Scanner(System.in);
		int a=sc1.nextInt();
		System.out.println("enter the second number");
		Scanner sc2=new Scanner(System.in);
		int b=sc2.nextInt();
		System.out.println("enter the third number");
		Scanner sc3=new Scanner(System.in);
		DataInputStream dis=new DataInputStream(System.in);
		String r=dis.readLine();
		System.out.flush();
		if(r!=null)
		{
			int c=Integer.parseInt(r);
			System.out.println(a*b*c);
		}
		else
		{
			System.out.println(a*b);
		}
	}
}

[Ankit Garg]

Did you try add && r.length() > 0 to your if condition?