Input Output in Java

Input and output (I/O) in Java refers to the process of reading data from external sources (input) and writing data to external destinations (output) within a Java program. Input and output operations are essential for interacting with users, reading data from files or network streams, and writing data to files or other output devices. Java provides several classes and APIs for performing input and output operations efficiently.

In the below PDF we discuss about Input Outpit in Java  in detail in simple language, Hope this will help in better understanding.

Input in Java:

  • Reading from Standard Input: Java provides to read input from the standard input stream (usually the keyboard). This is typically used with Scanner or BufferedReader classes for reading input from the console.
Scanner scanner = new Scanner(;
String userInput = scanner.nextLine();
  • Reading from Files: Java provides classes like File, FileReader, and BufferedReader for reading data from files.
File file = new File("input.txt");
BufferedReader reader = new BufferedReader(new FileReader(file));
String line = reader.readLine()

Output in Java:

Similarly, Java offers several methods for outputting data:

  • Writing to Standard Output (System.out): Developers can use System.out.println() or System.out.print() to display output to the console.
public class OutputExample {
public static void main(String[] args) {
System.out.println("Hello, World!");
  • Writing to Files: Java provides classes like FileOutputStream or BufferedWriter to write data to files.

public class FileOutputExample {
public static void main(String[] args) {
try (BufferedWriter writer = new BufferedWriter(new FileWriter("output.txt"))) {
writer.write("Hello, World!");
} catch (IOException e) {


Input and output operations are essential for building interactive and data-driven Java applications. Java’s rich set of classes and APIs for input and output make it straightforward to read data from various sources, such as files and network streams, and write data to different destinations, such as files and output streams. Understanding and mastering input and output operations are essential skills for Java developers to create robust and efficient applications.

Must Read:Variables in Java

Related Question

Input and output, commonly referred to as I/O, in Java refer to the process of transferring data between a program and external sources such as files, keyboards, screens, and other devices.

Console input in Java can be achieved using the Scanner class from the java.util package. You create a Scanner object and use its methods like nextInt(), nextLine(), etc., to read input from the console.

Console output in Java is typically accomplished using the System.out.println() method. You can also use System.out.print() for output without a newline character.

The System.out object in Java is an instance of PrintStream class that provides methods to output data to the standard output stream, typically the console.

In Java, you can handle exceptions using try-catch blocks or by declaring the exceptions to be thrown in the method signature. It’s important to handle exceptions properly to ensure robustness in I/O operations.


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