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Java: Read txt files and write content to txt files (with source code)
mvwiw2qi
- Post By mvwiw2qi
- 6 days ago
Java implements reading and writing TXT files
1. Project background and introduction
In the actual development process, text files (TXT files) are a commonly used data storage and exchange format. Whether in logging, configuration files, data backup, or simple data transmission, TXT files play an important role. Mastering how to use Java to read TXT file contents and write data to TXT files is of great practical significance for developers to handle file I/O operations.
This project will implement two basic functions through Java I/O streams (and try-with-resources syntax):
• Read TXT file contents: read data from a text file into the program (for example, save it as a string).
• Write TXT file contents: write data in the program to a text file for storage.
Through this project, readers can not only become familiar with the use of Java I/O basic classes, but also learn how to correctly close resources and handle exceptions, so as to write robust file reading and writing programs.
2. Related knowledge
2.1 Java I/O Basics
Java provides a rich I/O library, the most commonly used of which are:
• FileReader and FileWriter: used to read and write text files, using the platform character encoding by default.
• BufferedReader and BufferedWriter: buffering character streams can improve reading and writing efficiency, and provide a method to read text by line.
2.2 try-with-resources syntax
Starting from Java 7, the try-with-resources syntax can automatically close resources that implement the AutoCloseable interface, simplifying the code and reducing the risk of memory leaks. For example:
try (BufferedReader reader = new BufferedReader (new FileReader ("file.txt"))) { // Perform file reading operations here } catch (IOException e) { print StackTrace(); }
2.3 File Path and Character Encoding
• File Path: You can use absolute or relative paths in the code. Relative paths are usually based on the project root directory, so you need to pay attention to the correctness of the path during debugging.
• Character Encoding: If you need to specify a specific character encoding, you can use InputStreamReader and OutputStreamWriter to wrap the byte stream.
3. Project Implementation Ideas
This project is mainly divided into two parts:
1. Read TXT files
1. Use FileReader and BufferedReader classes to read file contents.
2. Use the readLine() method to read text line by line, and accumulate each line into a StringBuilder, and finally return the complete text string.
2. Write TXT files
1. Use FileWriter and BufferedWriter classes to write text.
2. Write the target string to the file, overwriting or creating a new text file.
In addition, in order to ensure the robustness of the program and the simplicity of the code, the try-with-resources syntax is used to automatically manage resource closure and perform error handling after catching exceptions.
4. Complete code implementation The following is a complete Java code example that implements the functions of reading and writing TXT files, with detailed Chinese comments:
import java.io.*; /** * The ReadWriteTxtFile class implements the basic functionality of reading and writing TXT files.* This program demonstrates how to use BufferedReader to read text file contents, * and how to use BufferedWriter to write strings to text files.*/ public class ReadWriteTxtFile { /** * Reads a TXT file from the specified path and returns the content as a string. (new FileReader(filePath))) { String line; // Read a text file line by line while ((line = reader.readLine()) != null) { content.append(line); content.append(System.lineSeparator()); // Add a newline character to keep the original format/** * Write the specified content to a TXT file. (); } } /** * @param filePath File path, can be an absolute path or a relative path * @param content The text content to be written */ public static void writeTxtFile(String filePath, String content) { // Use try-with-resources to automatically close BufferedWriter try (BufferedWriter writer = new BufferedWriter(new FileWriter(filePath))) { writer.write(content); } catch (IOException e) { System.err.println("An error occurred while writing the file: " + e.getMessage()); e.printStackTrace(); } } /** * Main function, used to test the functions of reading and writing TXT files. String fileContent = readTxtFile(readFilePath); if (fileContent != null) { System.out.println("The read file content is as follows: "); System.out.println(fileContent); } else { System.out.println("Failed to read file. Please check the file path or file status.");} // Define the content to be written String newContent = "This is the content written to the text file.\nThis is the second line of text."; // Call the writeTxtFile method to write the content to the file writeTxtFile(writeFilePath, newContent); System.out.println("The content has been successfully written to the file: " + writeFilePath); } }
5. Code Interpretation
5.1 Read TXT File
• Method readTxtFile(String filePath)
• Use BufferedReader and FileReader to read the file in character stream mode.
• Use readLine() method to read the file content line by line and append each line to StringBuilder, while adding system line break to maintain the original format.
• Use try-with-resources syntax to ensure that BufferedReader is automatically closed after reading to prevent resource leakage.
• If an exception occurs during reading, print the error message and return null.
5.2 Write TXT File
• Method writeTxtFile(String filePath, String content)
• Use BufferedWriter and FileWriter to write the string to the file in character stream mode.
• Directly call writer.write(content) to write the entire string to the target file.
• Also use try-with-resources to automatically close BufferedWriter to ensure that resources are released correctly.
• If an exception occurs during the writing process, print an error message.
5.3 Main function test
• Method main(String[] args)
• First specify the path of the file to be read (make sure the file exists, otherwise the reading will fail).
• Call the readTxtFile method to read the file content and output the result to the console.
• Define a new text content and call the writeTxtFile method to write the content to the specified file.
• The test program can correctly read and write text files, which is convenient for developers to verify functions.
6. Project summary and outlook
This project implements the basic functions of reading TXT files and writing content to TXT files through Java I/O. The main gains include:
1. Master basic file I/O operations
By reading and writing text files, readers can become familiar with the use of character streams in Java and the basic process of file reading and writing.
2. Manage resources with try-with-resources
Using the try-with-resources syntax, ensure that related resources are automatically closed after the file operation is completed, reducing memory leaks and resource occupation problems.
3. Exception handling mechanism
Reasonably capture exceptions in file operations and output error information to help debug and improve the robustness of the program.
4. Expansion and optimization direction
1. File encoding processing: When processing multilingual text, you can specify a specific character encoding (such as UTF-8), such as using InputStreamReader and OutputStreamWriter.
2. Large file processing: For very large files, you can use segmented reading to avoid loading the entire file into memory at one time.
3. Graphical interface integration: Combined with Java Swing or JavaFX, you can develop a simple file editor to display and edit file contents.
In short, through the implementation of this project, readers can not only master the reading and writing operations of text files, but also lay the foundation for further development of file management, data processing and text editing tools. I hope this blog post can provide you and your readers with valuable reference and inspiration in the field of Java file operations.
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