BufferedReader vs. Scanner in Java
Table of Contents
- 1. Introduction
- 2. Key Differences Between BufferedReader and Scanner
- 2.1 BufferedReader: Overview and Usage
- 2.2 Scanner: Overview and Usage
- 3. Comparison Table: BufferedReader vs. Scanner
- 4. Detailed Explanation and Use Cases
- 4.1 BufferedReader for Multithreaded Applications
- 4.2 Scanner for Parsing Input Data
- 5. Conclusion
1. Introduction
Java provides multiple ways to read input from files or streams, with two popular options being BufferedReader and Scanner. Both classes serve the purpose of reading data, but they differ in performance, use cases, and characteristics. In this article, we will compare the two and highlight when to use each, based on the size of the buffer, performance, and application scenarios.
This guide is intended for beginners and developers who have basic knowledge of Java and want to deepen their understanding of input handling.
2. Key Differences Between BufferedReader and Scanner
2.1 BufferedReader: Overview and Usage
BufferedReader is part of the java.io package and is primarily used for reading large chunks of data efficiently. It is known for its ability to read text from an input stream and buffer the characters for optimal performance.
- Buffer Size: BufferedReader uses a larger buffer (8KB byte buffer), making it more suitable for reading large files or handling streams.
- Synchronous: BufferedReader is synchronous, which means it can be used in multithreaded environments.
- Performance: Since BufferedReader reads raw characters, it is slightly faster when the goal is to read a large sequence of characters without parsing the input.
2.2 Scanner: Overview and Usage
Scanner belongs to the java.util package and is designed for parsing input. It can be used to read different types of data (e.g., integers, strings, etc.) by breaking down the input into tokens.
- Buffer Size: Scanner uses a smaller buffer (1KB char buffer), making it more suited for smaller inputs or cases where parsing is required.
- Not Synchronous: Scanner is not synchronized and, therefore, not recommended for multithreaded applications.
- Parsing Capability: While Scanner is slower due to its parsing functionality, it is the preferred choice when working with primitive data types like int, double, and String.
3. Comparison Table: BufferedReader vs. Scanner
| Feature | BufferedReader | Scanner |
|---|---|---|
| Package | java.io | java.util |
| Synchronous | Yes | No |
| Buffer Size | Larger (8KB byte buffer) | Smaller (1KB char buffer) |
| Performance | Faster for large character input | Slower due to parsing overhead |
| Multithreading | Suitable for multithreaded apps | Not recommended for multithreading |
| Primary Use | Reading large chunks of text | Parsing and reading smaller inputs |
4. Detailed Explanation and Use Cases
4.1 BufferedReader for Multithreaded Applications
BufferedReader is ideal for multithreaded applications due to its synchronous nature. When reading large files, such as log files or CSVs, BufferedReader provides a high-performance solution by buffering the data before reading, reducing the number of I/O operations.
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import java.io.BufferedReader; import java.io.FileReader; import java.io.IOException; public class BufferedReaderExample { public static void main(String[] args) { try (BufferedReader br = new BufferedReader(new FileReader("file.txt"))) { String line; while ((line = br.readLine()) != null) { System.out.println(line); } } catch (IOException e) { e.printStackTrace(); } } } |
Explanation:
- The BufferedReader reads a line at a time from the file file.txt.
- The larger buffer ensures that even large files are processed efficiently.
4.2 Scanner for Parsing Input Data
Scanner shines when you need to parse input data into specific types, such as reading user input or processing small text files where each token needs to be processed. It can directly convert input into primitive types, which makes it versatile in handling formatted data.
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import java.util.Scanner; import java.io.File; import java.io.FileNotFoundException; public class ScannerExample { public static void main(String[] args) { try (Scanner scanner = new Scanner(new File("file.txt"))) { while (scanner.hasNext()) { System.out.println(scanner.nextLine()); } } catch (FileNotFoundException e) { e.printStackTrace(); } } } |
Explanation:
- Scanner reads the file file.txt and prints each line.
- While easier to use for tokenizing input, Scanner is slower compared to BufferedReader due to its parsing mechanism.
5. Conclusion
Both BufferedReader and Scanner serve unique purposes in Java file handling. BufferedReader is best suited for large file reads and multithreaded environments due to its synchronous nature and larger buffer. On the other hand, Scanner is ideal when input parsing is required, despite its slower performance due to the smaller buffer and tokenizing overhead.
Understanding when to use each class can improve the performance and maintainability of your Java applications.