Lecture 6: Scanner and DataInputStream class in Java

Scanner and DataInputStream class in Java:
Program: To read two integer numbers from console or keyboard using Scanner class and add these two numbers and display it.
import java.util.Scanner; //program uses class Scanner which is built in class and in package util
public class Addition
{
public static void main(String args[])
{
Scanner input = new Scanner(System.in);
int number1;
int number2;
int sum;
System.out.print(“Enter first integer :”);
number1 = input.nextInt(); //read first integer from user
System.out.print(“Enter second integer :”);
number2 = input.nextInt(); //read second integer from user
sum = number1 + number2;
System.out.printf(“Sum is %d”,sum);
}
}

Output:
Enter first integer : 40
Enter second integer : 50
Sum is 90
Explanation:
In above program:
System.in – is standard input buffer, enables Java applications to read information typed by user from keyboard. Now in program Scanner class’s object input is acts as a stream present between keyboard and RAM. Using this stream we can scan any value by using different methods present in Scanner class. That is for scanning integer value method present is nextInt() and this method returns integer value.
System.out.print(“”); here class System is a class of package java.lang. notice that class System is not imported with an import declaration at beginning of program. Because package java.lang is imported in every Java program by default.
To scan string from keyboard use:
String name = input.nextLine(); //read a line of text.
Double d =input.nextDouble(); //read double
Float f = input.nextFloat(); //read float
number1 = input.nextInt(); This method to obtain an integer from user (keyboard), at this point program waits for user to type number and press enter key to submit the number to program.
Memory concept:
Variables names such as number1, number2 and sum actually correspond to locations in the computer’s memory. Every variable has a name, a type, a size and value.
number1 = input.nextInt(); //read number from user.

1.21 Program: To read integer number and float number from console or keyboard using DataInputStream class.
import java.io.*;
public class ReadDataInputStream
{
public static void main(String args[]) throws IOException
{
DataInputStream in = new DataInputStream(System.in);
int intnum = 0;
float fnum = 0.0f;
System.out.println("Enter an integer :");
intnum = Integer.parseInt(in.readLine());
System.out.println("Enter float number :");
fnum = Float.parseFloat(in.readLine());
System.out.println("Int number = "+intnum);
System.out.println("Float number = "+fnum);
}
}
Output:
Enter an integer :
22
Enter float number :
66.99
Int number = 22
Float number = 66.99



Prof. Amol M. Jagtap
M.Tech CSE
7972761065

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Prof. Amol M. Jagtap
For more contact : 7972761065