Get Keyboard Input in Basic Java Program

By | June 30, 2019

Task: Steps to Get Keyboard Input in Basic Java Program

The Input For Java Console Applications ( Basic Java Programs )

Java Console Applications are the basic programs to start learning Java Programming Language. The new Java programmers wish to write general programs with run time input from the user. For example, suppose  we wish to write a program to input a number and display its square.  Therefore, on execution of this Java program, it will show a message to user for keyboard input. Hence, the user will enter a number and press Enter key. Here is a sample run of the program.

Enter a number to calculate square=

Now let us assume that the user will type 10 from the keyboard and press Enter key. The Java program will show the following output:

Enter a number to calculate square=10
Square = 100BUILD SUCCESSFUL (total time: 10 seconds)

Simple and Short Steps:

Step1: import Scanner class
import java.util.Scanner;

Step 2:Create an object let "keyboard" of Scanner class
by passing it System.in (standard system input device)
Scanner keyboard = new Scanner(System.in);

Step 3://Step 3
Show message to enter data
System.out.print("Enter a number to calculate square=");

Step 4:
call nextInt() method to initiate integer input
num = keyboard.nextInt();
How to get user input from keyboard in Java Programs

How to get user input from keyboard in Java Programs

How To Get Keyboard Input From User in Java Programs

We can write Java code to get input through keyboard from the user in the following four steps: 

Use import statement to Import Scanner class

import java.util.Scanner;

Create an object say “keyboard” of Scanner class

Scanner keyboard = new Scanner(System.in);

Here keyboard is an object of Scanner class and we pass System.in to represent standard system input device that is keyboard.

Show a message to user to enter data

System.out.print("Enter a number to calculate square=");

Use suitable method to initiate key board input

For example, the method  nextInt() is used to initiate integer number input from keyboard.

num = keyboard.nextInt();

Actually,  when user types a number and presses Enter key from keyboard, say he types 10 and presses Enter. Consequently, 10 is stored in num variable on left side of assignment statement.

We can use num variable to calculate square of number as below:

square = num * num; And to show the result, we will write:
Syste.out.print("Square =" + square);
Use of Scanner class for keyboard input in Java programs

Use of Scanner class for keyboard input in Java programs

Getting Keyboard Input in Basic Java Program

Other useful methods in Scanner class for input of different type of data are as follows:

Method Description
nextBoolean() Used to read a boolean value from the user
nextByte() It is used to read a byte value from the user
nextDouble() to read a double value from the user
nextFloat() for reading a float value from the user
nextInt() It is used to read a int value from the user
nextLine() Use this method to read a String value from the user
nextLong() We use it to read a long value from the user
nextShort() It is used to read a short value from the user

The complete source code of a Java Program explaining to Get Keyboard Input in Basic Java Program is here: Write a Java Program to input a number and display its square.

3 thoughts on “Get Keyboard Input in Basic Java Program

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  2. Pingback: Java Program To Input a Number and Display Its Square | EasyCodeBook.com

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