This code doesn't work. Why? thanks.

import java.util.ArrayList;

import java.util.Scanner;

public class SimpleEventDemo {
/** Main method */
public static void main(String[] args) {

ArrayList<Integer> numbers = new ArrayList<Integer>();

// Create a Scanner
Scanner input = new Scanner(System.in);

// Read all numbers
while(input.hasNextInt()){
System.out.print("Enter a number: ");

// Convert string into integer
numbers.add(input.nextInt());
}
System.out.print(numbers);
}
}

What's it supposed to do?
Please explain what the problem is or why the output of the program is wrong

It creates an arraylist and then it prompts user for numbers to populate the list.
And then it prints out the list.

Ok, you've answered the first question. Now how about this one:

Please explain what the problem is or why the output of the program is wrong

The while loop doesn't work. If I remove the while loop. It takes one number and it adds the number to the list and prints it out. But with the while loop the program just hangs.

Ok, now we know the problem

Can you copy the console from when you run the code and paste it here?

it doesn't run, it just freezes

Its running and waiting for you.
Enter a number.

you are right. for some reason it doesn't print "Enter a number: " first time.
Thanks.

That should tell you something about what the hasNextInt() method is doing.

Read the API doc for an explanation:

Quote:

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Both hasNext and next methods may block waiting for further input.

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Converting the while loop to a do-while loop could work. Check it for bugs if the first input isn't actually an integer though... (i.e. I haven't tested this at all)