Transcript Keyboard Class

Java
Scanner Class
Keyboard Class
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
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;
1. The Scanner Class
2. The Keyboard Class

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
import java.util.*;
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
Scanner Class

The first thing you need to do is create an
instance of the Scanner class
Class
Name
Creates an
instance of the
class
Constructor
Scanner Inputs

You could input many different data types;
Data Type
Method
String
String str = s.next();
double
double d = s.nextDouble();
long
long l = s.nextLong();
short
short sh = s.nextShort();
byte
byte b = s.nextByte();
float
float f = s.nextFloat();
boolean
boolean bo = s.nextBoolean();
import java.util.Scanner;
Examples
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.");
}
}
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
Using the Keyboard Class
Data Type
Method
int
Keyboard.readInt();
byte
Keyboard.readByte();
short
Keyboard.readShort();
long
Keyboard.readLong();
float
Keyboard.readFloat();
double
Keyboard.readDouble();
char
Keyboard.readChar();
boolean
Keyboard.readBoolean();
Keyboard.readString();
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.");
}
}
Which is better to use?
Why?