Handling user input and displaying output is fundamental in creating interactive programs. Java provides flexible mechanisms for reading input from users and printing output to the console or files.
Understanding how to use classes like Scanner and BufferedReader helps you build applications that interact dynamically with users or data sources.
Java provides two common ways to perform input:
java.util, easy to use for reading input from the keyboard. Methods like nextLine(), nextInt(), and nextDouble() are used.java.io, suitable for reading larger inputs. It works with InputStreamReader and requires exception handling.For output, System.out.print and System.out.println are used to display information on the console.
Learn how to use Scanner for console input in Java.
import java.util.Scanner;
public class ScannerExample {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.print("Enter your name: ");
String name = input.nextLine();
System.out.println("Hello, " + name + "!");
input.close();
}
}
import java.io.*;
public class BufferedReaderExample {
public static void main(String[] args) throws IOException {
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
System.out.print("Enter your age: ");
String age = reader.readLine();
System.out.println("You are " + age + " years old.");
}
}
Used in user registration forms and data input interfaces in console applications.
Reading values from users for storing in files or databases.
Command-line tools that require user commands and arguments use input classes.
Scanner is easier to use for parsing primitives and strings with built-in methods, while BufferedReader is faster and suitable for reading lines or large chunks of text.
Closing releases the underlying system resources (like input streams) to prevent memory leaks or locking issues.
Yes, Scanner can read from files using new Scanner(new File("filename")) by importing java.io.File and handling exceptions.