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Java Program to take input from user using BufferedReader class.

Java Code Example — Input/Output Programs

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Java Program to take input from user using BufferedReader class.

Objective

Write a Java program to take input using BufferedReader and InputStreamReader.

Algorithm / Approach

  1. Import java.io.*.
  2. Add throws Exception to the main method signature.
  3. Create an InputStreamReader to translate bytes from System.in into characters.
  4. Wrap it in a BufferedReader to buffer the characters for efficient reading of whole lines.
  5. Use in.readLine() to get string input, and manually parse it using Integer.parseInt() for numbers.
InputDemo.java 
import java.io.*;
class InputDemo{
 public static void main(String[] a)
  throws Exception
 {
  Reader r=new InputStreamReader(System.in);		
  BufferedReader in=new BufferedReader(r);
  System.out.print("Enter Name: ");
  String name = in.readLine();
  System.out.print("Enter Age: ");
  int age =Integer.parseInt(in.readLine());
  System.out.print("Enter Marks: ");
  double m=Double.parseDouble(in.readLine());
  System.out.println("Name- "+name);
  System.out.println("Age- "+age);
  System.out.println("Marks- "+m);
 }
}

Expected Output

Enter Name: Alok
Enter Age: 23
Enter Marks: 71.2
Name- Alok
Age- 23
Marks- 71.2

Explanation of the Program

  • Before the Scanner class was introduced in Java 5, BufferedReader was the standard way to read console input.
  • It is still heavily used today because it is significantly faster than Scanner, making it the preferred choice for competitive programming where reading massive amounts of I/O data quickly is critical.
  • However, it is less convenient: it only reads raw Strings, meaning you must manually parse all numeric data, and it throws checked IOExceptions that must be handled.

Complexity

Time Complexity O(1)
Space Complexity O(1)
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