Java

1. Java Scanner Class Keyboard Class

2. User Interaction • So far when we created a program there was no human interaction • Our programs just simply showed one output • In order for users to interact with our programs we need to use external classes

3. External Classes • External classes are ready made classes that are used to allow users to interact with a program • Two examples of external classes are; • The Scanner Class • The Keyboard Class

4. Using External Classes • In order to use external classes you would need to let your program know that you would like to use them • In order to call ALL external classes you need to use the following code snippet

5. Scanner & Keyboard Class • The scanner and keyboard classes are both used to allow users to interact with the program • They are used to ask users for an input • The input is normally done using the actual keyboard

6. Scanner Class • The first thing you need to do is create an instance of the Scanner class Class Creates an instance of the class Constructor Name

7. Scanner Inputs • You could input many different data types;

8. import java.util.Scanner; class test { public static void main (String args[]){ //Create an instance of the Scanner Scanner s = new Scanner(System.in); System.out.print("Enter your name : "); //Since the name is a String the String //has to be used String name = s.next(); System.out.println("How old are you ? "); //The age can be stored in a long long age = s.nextLong(); System.out.println("You are "+name+" and you are "+age+" years old."); } } Examples

9. Keyboard Class • This class is also used to let users input data from the keyboard • The user can input the same data types we spoke about when we used the scanner class

10. Using the Keyboard Class

11. class test { public static void main (String args[]){ System.out.print("Enter your name : "); String name = Keyboard.readString(); System.out.println("How old are you ? "); long age = Keyboard.readLong(); System.out.println("You are "+name+" and you are "+age+" years old."); } }

12. Which is better to use? Why?