Java I/O Streams
Understanding input and output operations in Java
📁 What are I/O Streams?
Java I/O Streams are used to read data from input sources and write data to output destinations. They provide a consistent way to handle data flow in Java applications efficiently.
// Simple I/O Stream example
import java.io.*;
public class StreamExample {
public static void main(String[] args) {
System.out.println("Hello, I/O Streams!");
}
}
Output:
Hello, I/O Streams!
Types of I/O Streams
Input Streams
Read data from sources
InputStream input = new FileInputStream("file.txt");Output Streams
Write data to destinations
OutputStream output = new FileOutputStream("file.txt");Character Streams
Handle text data efficiently
Reader reader = new FileReader("text.txt");Byte Streams
Handle binary data
byte[] data = {65, 66, 67};🔹 Basic Stream Operations
Common operations you'll perform with I/O streams:
import java.io.*;
public class BasicStreamOps {
public static void main(String[] args) {
try {
// Reading from a file
FileInputStream fis = new FileInputStream("input.txt");
int data = fis.read();
System.out.println("First byte: " + data);
fis.close();
// Writing to a file
FileOutputStream fos = new FileOutputStream("output.txt");
fos.write(65); // Writes 'A'
fos.close();
} catch (IOException e) {
System.out.println("Error: " + e.getMessage());
}
}
}Output:
First byte: 72
File 'output.txt' created with content 'A'
🔹 Stream Hierarchy
Understanding the Java I/O class hierarchy:
Byte Streams:
- InputStream - Abstract class for reading bytes
- OutputStream - Abstract class for writing bytes
- FileInputStream/FileOutputStream - File operations
Character Streams:
- Reader - Abstract class for reading characters
- Writer - Abstract class for writing characters
- BufferedReader/BufferedWriter - Buffered operations
🔹 Exception Handling
Always handle exceptions when working with I/O streams:
import java.io.*;
public class SafeStreamHandling {
public static void main(String[] args) {
FileInputStream fis = null;
try {
fis = new FileInputStream("data.txt");
int content = fis.read();
System.out.println("Content: " + (char)content);
} catch (FileNotFoundException e) {
System.out.println("File not found!");
} catch (IOException e) {
System.out.println("Error reading file!");
} finally {
if (fis != null) {
try {
fis.close();
} catch (IOException e) {
System.out.println("Error closing file!");
}
}
}
}
}