How to Take Input From User in Java?

Java brings various Streams with its I/O package that helps the user to perform all the input-output operations. These streams support all the types of objects, data-types, characters, files, etc to fully execute the I/O operations. There are two ways by which we can take input from the user or from a file

◉ BufferedReader Class

◉ Scanner Class

1. BufferedReader

It is a simple class that is used to read a sequence of characters. It has a simple function that reads a character another read which reads, an array of characters, and a readLine() function which reads a line.

InputStreamReader() is a function that converts the input stream of bytes into a stream of character so that it can be read as BufferedReader expects a stream of character.

BuffferedReader can throw checked Exceptions

// Java Program For BufferedReader Class 

import.java.io.*; 

public class BufferedReader 

{ 

// Main Method 

public static void main(String [] args) 

{ 

// Creating BuferedReader Object 

// InputStreamReader converts bytes to 

// stream of character 

BufferedReader BufferedReader_Name = new

BufferedReader(new InputStreamReader(System.in)); 

// Asking for input from user 

System.out.println("Enter String : "); 

System.out.println("Enter Integer : "); 

// String reading internally 

String String_name = BufferedReader_Name.readLine(); 

// Integer reading internally 

int Integer_value = 

Integer.parseInt(BufferedReader_name.readLine()); 

// Printing String 

System.out.println("Entered String : "+ String_name); 

//Printing Integer  

System.out.println("Entered Integer : "+ Integer_value); 

} 

}

Output : 

Entered String: Oraclejavacertified

Entered Integer: 123

2. Scanner

It is an advanced version of BufferedReader which was added in later versions of Java. The scanner can read formatted input. It has different functions for different types of data types. 

◉ The scanner is much easier to read as we don’t have to write throws as there is no exception thrown by it.

◉ It was added in later versions of Java

◉ It contains predefined functions to read an Integer, Character, and other data types as well.

Syntax for Scanner

Scanner Scanner_name = new Scanner(System.in);

Syntax for importing Scanner Class: To use the Scanner we need to import the Scanner Class

import java.util.Scanner ;  

Inbuilt Scanner functions are as follows

◉ Integer: nextInt()

◉ Float: nextFloat()

◉ String : readLine()

Hence, in the case of Integer and String in Scanner, we don’t require parsing as we did require in BufferedReader.

// Java Program to show how to take 

// input from user using Scanner Class 

import java.util.Scanner; 

class Scanner { 

public static void main( String[] args ) 

{ 

// Scanner definition 

Scanner Scanner_name= new Scanner(System.in); 

// input is a string read 

// by readLine() function 

String str= str.readLine(); 

// print string 

System.out.ptintln("Entered String : "+ str); 

// input is an Integer 

// read by nextInt() function 

int x= Scanner_name.nextInt(); 

// print integer 

System.out.ptintln("Entered Integer : "+ x); 

// input is a floatingValue 

// read by nextFloat() function 

float f = Scanner_name.nextFloat(); 

// print floating value 

System.out.ptintln("Entered FloatValue : "+ f); 

} 

}

Output :

Entered String: Oraclejavacertified

Entered Integer: 123

Entered FloatValue: 123.0

Differences Between BufferedReader and Scanner

◉ BufferedReader is a very basic way to read the input generally used to read the stream of characters. Its gives an edge over Scanner as it is faster than Scanner because Scanner does lots of post-processing for parsing the input; as seen in nextInt(), nextFloat()

◉ BufferedReader is more flexible as we can specify the size of stream input to be read. (In general, it is there that BufferdReader reads lager input than Scanner)

◉ These two factors come into play when we are reading larger input. In general, the Scanner Class serves the input.

◉ BufferdReader is preferred as it is synchronized. While dealing with multiple threads it is preferred.

◉ For decent input, easy readability. The Scanner is preferred over BufferedReader.