File Modification And Merging

Introduction

Managing files often requires modifying and merging content dynamically. Whether you're updating logs, editing configuration files, or combining multiple directories, the file-worker library provides utilities to modify and merge files and directories efficiently.

Imagine you need to clean up log files by deleting specific lines, merge all Markdown files in a documentation folder, or chain file operations fluently. This library helps automate such operations with minimal, readable code.

Features Overview

• Modify file content line by line.
• Delete specific lines from a file by index.
• Fluent API support: Methods returning File or Path objects for easy method chaining.
• Extension-based concatenation: Merge all files with a specific extension in a directory (optionally recursive).
• Merge directories while handling conflicts intelligently.
• Perform bulk modifications on files.

Getting Started

For installation and dependencies, refer to the Getting Started guide.

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Modifying and Concatenating Files with ModifyFileExtensions

The ModifyFileExtensions class provides methods for updating file content efficiently and merging multiple files.

Example: Modifying a File Line by Line (Fluent API)

The library now supports a Fluent API, allowing you to chain operations by returning the modified Path or File.

Path filePath = Path.of("sample.txt");

// modifyFileAndGet returns the Path, enabling further operations
Path modifiedPath = ModifyFileExtensions.modifyFileAndGet(filePath, StandardCharsets.UTF_8, (index, line) -> line.toUpperCase());

System.out.println("File content converted to uppercase at: " + modifiedPath);

Example: Concatenating Files by Extension

A common task is merging all files of a specific type within a directory (e.g., combining all .md or .log files).

File sourceDirectory = new File("src/main/resources/docs");
File resultFile = new File("target/combined-docs.md");

// Concatenates all .md files in the directory alphabetically into the result file
ModifyFileExtensions.concatenateFilesWithExtension(sourceDirectory, ".md", resultFile);

System.out.println("All markdown files merged successfully into: " + resultFile.getName());

Note: There is also a concatenateFilesWithExtensionRecursive method available if you need to search through subdirectories.

Example: Concatenating a Specific List of Files

If you already have a specific list of files, you can concatenate them directly:

List<File> filesToConcatenate = List.of(new File("file1.txt"), new File("file2.txt"));
File resultFile = new File("merged.txt");

ModifyFileExtensions.concatenateAll(filesToConcatenate, resultFile);

Unit Test Coverage

The ModifyFileExtensionsTest class verifies this functionality, including the new extension-based concatenation:

@Test
public void testConcatenateFilesWithExtension() throws IOException {
    // Arrange
    File testDir = new File("test-dir");
    testDir.mkdirs();
    LineAppender.appendLines(new File(testDir, "a.txt"), new String[]{"Line 1"});
    LineAppender.appendLines(new File(testDir, "b.txt"), new String[]{"Line 2"});
    File resultFile = new File("result.txt");

    // Act
    File returnedFile = ModifyFileExtensions.concatenateFilesWithExtension(testDir, ".txt", resultFile);

    // Assert
    assertEquals(resultFile, returnedFile);
    String actual = ReadFileExtensions.fromFile(resultFile);
    assertEquals("Line 1\nLine 2\n", actual); // Files are processed in alphabetical order
    
    // Cleanup
    DeleteFileExtensions.delete(testDir);
    DeleteFileExtensions.deleteFile(resultFile);
}

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Deleting Specific Lines with DeleteLinesByIndexInFile

The DeleteLinesByIndexInFile class allows you to remove specific lines from a file by leveraging the modification engine.

Example: Deleting Lines by Index

List<Integer> linesToDelete = List.of(1, 3); // 0-based or 1-based depending on implementation specifics
FileChangeable deleter = new DeleteLinesByIndexInFile(linesToDelete);

ModifyFileExtensions.modifyFile(Path.of("data.csv"), deleter);

System.out.println("Selected lines deleted from the file.");

Unit Test Coverage

The DeleteLinesByIndexInFileTest class ensures correct behavior:

@Test
public void testApply() throws IOException {
    Path filePath = Path.of("test-data.csv");
    List<Integer> linesToDelete = Arrays.asList(1, 4);

    ModifyFileExtensions.modifyFile(filePath, new DeleteLinesByIndexInFile(linesToDelete));

    List<String> lines = ReadFileExtensions.readLinesInList(filePath);
    assertFalse(lines.contains("Line 2")); // Assuming 1-based index deletion removed it
}

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Merging Directories with MergeDirectoryExtensions

The MergeDirectoryExtensions class helps combine directories while managing file conflicts.

Example: Merging Directories

File targetDir = new File("mergedDir");
File dir1 = new File("sourceDir1");
File dir2 = new File("sourceDir2");

MergeDirectoryExtensions.merge(targetDir, dir1, dir2);

System.out.println("Directories merged successfully!");

Handling File Conflicts

If the same file exists in both directories, the library intelligently resolves conflicts based on timestamps and content differences, preventing accidental data loss.

Unit Test Coverage

The MergeDirectoryExtensionsTest class ensures directory merging works as expected:

@Test
public void testMerge_TwoDirectories_NoConflicts() throws IOException {
    File targetDir = Files.createTempDirectory("target").toFile();
    File dir1 = Files.createTempDirectory("dir1").toFile();
    File dir2 = Files.createTempDirectory("dir2").toFile();

    File file1Dir1 = new File(dir1, "file1.txt");
    File file1Dir2 = new File(dir2, "file2.txt");
    StoreFileExtensions.toFile(file1Dir1, "content1");
    StoreFileExtensions.toFile(file1Dir2, "content2");

    MergeDirectoryExtensions.merge(targetDir, dir1, dir2);

    assertTrue(new File(targetDir, "file1.txt").exists());
    assertTrue(new File(targetDir, "file2.txt").exists());
    
    // Cleanup
    DeleteFileExtensions.delete(targetDir);
    DeleteFileExtensions.delete(dir1);
    DeleteFileExtensions.delete(dir2);
}

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Merging Directories with MergeDirectoryExtensions

The MergeDirectoryExtensions class helps combine multiple directories into a single target directory while intelligently managing file conflicts.

Example: Merging Directories (Fluent API)

You can merge multiple source directories into a target directory. The new mergeAndGet method returns the target directory, allowing for fluent method chaining.

File targetDir = new File("target/mergedDir");
File dir1 = new File("source/backup_2023");
File dir2 = new File("source/backup_2024");

// mergeAndGet returns the targetDir, enabling further operations
File resultDir = MergeDirectoryExtensions.mergeAndGet(targetDir, dir1, dir2);

System.out.println("Directories merged successfully into: " + resultDir.getAbsolutePath());

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Conclusion

The file-worker library provides robust, fluent, and highly customizable tools for modifying files, deleting specific content, concatenating files by extension, and merging directories efficiently. Whether you're processing logs, editing data, or managing large file structures, this library simplifies file handling while maintaining academic and professional code quality.

Start using it today to automate your file operations and enhance productivity!

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