How to solve Java large file read error exception (LargeFileReadErrorExceotion)

How to solve Java large file read error exception (LargeFileReadErrorExceotion)

In Java development, dealing with large file reading is a common challenge. When the file size exceeds the memory limit, a Java large file read error exception (LargeFileReadErrorExceotion) may occur. This article describes several ways to solve this problem and provides corresponding code examples.

Method 1: Use buffer to read
A common mistake is to read the entire file into memory at one time. When the file is too large, it will cause memory overflow. To solve this problem, we can use a buffer to read the file line by line.

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

public class LargeFileReader {
    public static void main(String[] args) {
        BufferedReader reader = null;
        try {
            reader = new BufferedReader(new FileReader("large_file.txt"));
            String line;
            while ((line = reader.readLine()) != null) {
                // 处理每一行的数据
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (reader != null) {
                    reader.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

Method 2: Using RandomAccessFile
RandomAccessFile provides a mechanism for random access to files. We can read large file contents block by block by setting the buffer size.

import java.io.IOException;
import java.io.RandomAccessFile;

public class LargeFileReader {
    public static void main(String[] args) {
        RandomAccessFile raf = null;
        try {
            raf = new RandomAccessFile("large_file.txt", "r");
            byte[] buffer = new byte[1024]; // 1KB缓冲区
            int bytesRead;
            while ((bytesRead = raf.read(buffer)) != -1) {
                // 处理缓冲区中的数据
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (raf != null) {
                    raf.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

Method 3: Use memory-mapped files
Memory-mapped files allow us to map a file into memory and access the file like an array. This method can reduce the number of disk reads and improve the efficiency of reading files.

import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;

public class LargeFileReader {
    public static void main(String[] args) {
        Path path = Paths.get("large_file.txt");
        try (FileChannel fileChannel = FileChannel.open(path, StandardOpenOption.READ)) {
            long fileSize = fileChannel.size();
            MappedByteBuffer buffer = fileChannel.map(FileChannel.MapMode.READ_ONLY, 0, fileSize);
            byte[] data = new byte[(int)fileSize];
            buffer.get(data);
            // 处理数据
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Method 4: Use third-party libraries
If you don’t want to implement the logic of reading large files yourself, you can consider using some third-party libraries. For example, the Apache Commons IO library provides some simple yet powerful methods for handling large file reads.

import org.apache.commons.io.FileUtils;

import java.io.File;
import java.io.IOException;
import java.util.List;

public class LargeFileReader {
    public static void main(String[] args) {
        File file = new File("large_file.txt");
        try {
            List<String> lines = FileUtils.readLines(file, "UTF-8");
            for (String line : lines) {
                // 处理每一行的数据
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Summary:
When dealing with large file reading, we can use buffer line-by-line reading, random access files, memory mapped files and other methods to avoid the occurrence of LargeFileReadErrorExceotion exceptions. In addition, we can also use some third-party libraries to simplify the logic of reading large files. Choosing the appropriate method depends on the size of the file, read performance requirements, and other factors. I hope the solutions provided in this article can help you solve the problem of reading large files in Java.

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