Thread: hasNextInt() question

Hello all,

I'm relatively new to Java programming, I have a question about a piece of code from a video tutorial online:

static Scanner userInput = new Scanner(System.in);
 
	public static void main(String args[]){
 
		System.out.print("Your favorite number: ");
 
 
		if(userInput.hasNextInt()){
 
 
			int numberEntered = userInput.nextInt();
 
			System.out.println("You entered " + numberEntered);
		}else{
			System.out.println("Enter an integer next time.");
		}
}

How is the if statement (userInput.hasNextInt()) "true" if it doesn't ask for user input before the if statement? The scanner asks for user input inside the if statement:

int numberEntered = userInput.nextInt();

It works for me, I just don't understand how. Thanks for any help in advance!!!

When you declare the Scanner variable, it automatically begins to read for user input. It will pause at userInput.hasNextInt until it reads input.
So basically, user input is stored separately from the variables you declare. When you use .hasNextInt, it returns true or false, and when you use .nextInt, it returns the integer value itself.

the scanner class as it is used here is for taking input from the standard input which is the keyboard. the hasNext() method of class Scanner is a method that returns true until the end of file indicator is pressed. the end of file indicator for windows is ctrl z while that of linux is ctrl d. so the application/program will continue to take input until you press the end of file indicator