Java Program for Basic Input and Output

  • Java program to take input from user using scanner class.

In this Java program, we will learn about taking an integer, character, float and string input from user using Scanner class and then printing integer, character, float and string on screen using System.out.format method.

To perform any input operation using Scanner in a java program, we have to first import Scanner class as :

import java.util.Scanner; 
Scanner class in part of java.util package, which is s widely used for taking the input of basic data types like char, int, double etc from user. It breaks the keyboard input into tokens using a specified delimiter or using whitespace as default delimiter. It provide various method to parse basic data types from input.

While creating an object of Scanner class, we initialize it with predefined standard input stream System.in as

Scanner scanner = new Scanner(System.in);

Reading Integer using Scanner

To read integers, we use nextInt() method, which parses the next input token as an integer value and return it.

For Example,
int v_int;
v_int = scanner.nextInt();

Reading Character using Scanner

To read a character, we use next() method followed by charAt(0). next method returns the next input token as string as the charAt(0) returns the first character of token.

For Example,
char c;
c = scanner.next().charAt(0);

Reading String using Scanner

For reading a string, we use nextLine() method which returns a string till end of the line(newline character).

For Example,
String str;
str = scanner.nextLine();

Reading Float using Scanner

To read integers, we use nextFloat() method, which parses the next input token as an float value and return it.

For Example,
float v_float;
v_float = scanner.nextFloat();

Java Program for Taking input from user using Scanner

package com.tcc.java.programs;

import java.util.Scanner;

/**
 * Java Program to take input from user.
 */
public class TakingInput {
    public static void main(String[] args) {
        char c;
        int v_int;
        ;
        float v_float;
        String str;

        Scanner scanner;
        scanner = new Scanner(System.in);
        // Taking input from user
        System.out.println("Enter a String");
        str = scanner.nextLine();

        System.out.println("Enter a Character");
        c = scanner.next().charAt(0);

        System.out.println("Enter an Integer");
        v_int = scanner.nextInt();

        System.out.println("Enter a Float");
        v_float = scanner.nextFloat();

        // Printing data entered by user
        System.out.println("You Entered Following Data:");
        System.out.format("Char : %c\n", c);
        System.out.format("Integer : %d\n", v_int);
        System.out.format("Float : %f\n", v_float);
        System.out.format("String : %s", str);
    }
}
Output
Enter a Character
A
Enter an Integer
123
Enter a Float
1234.6
You Entered Following Data:
Char : A
Integer : 123
Float : 1234.599976
String : TectCrashCourse