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SampleUsage.md

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Introduction

The all common operation of this library is available through static methods of DiffUtils object. These methods are:

  • DiffUtils.diff(List<?> original, List<?> revised): Patch patch
  • DiffUtils.patch(List<?> original, Patch patch): List<?> revised
  • DiffUtils.unpatch(List<?> revised, Patch patch): List<?> original
  • DiffUtils.parseUnifiedDiff(List<String> diff): Patch patch
  • DiffUtils.getDiffRows(List<String> original, List<String> revised): List<DiffRow> diffRows

NOTE: All up-to-date examples can be found here.

Basic use in a Java App

Task 1: Compute the difference between to files and print its deltas

Solution:

import difflib.*;
 
public class BasicJavaApp_Task1 {
        // Helper method for get the file content
	private static List<String> fileToLines(String filename) {
		List<String> lines = new LinkedList<String>();
		String line = "";
		try {
			BufferedReader in = new BufferedReader(new FileReader(filename));
			while ((line = in.readLine()) != null) {
				lines.add(line);
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
		return lines;
	}

	public static void main(String[] args) {
                List<String> original = fileToLines("originalFile.txt");
                List<String> revised  = fileToLines("revisedFile.xt");
                
                // Compute diff. Get the Patch object. Patch is the container for computed deltas.
                Patch patch = DiffUtils.diff(original, revised);

                for (Delta delta: patch.getDeltas()) {
                	System.out.println(delta);
                }
	}
}

Task 2: Get the file in unified format and apply it as the patch to given text

Solution:

import difflib.*;
 
public class BasicJavaApp_Task2 {
        private List<String> originalList = Arrays.asList("aaa", "bbb", "ccc");

        // Helper method for get the file content
	private List<String> fileToLines(String filename) {
		List<String> lines = new LinkedList<String>();
		String line = "";
		try {
			BufferedReader in = new BufferedReader(new FileReader(filename));
			while ((line = in.readLine()) != null) {
				lines.add(line);
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
		return lines;
	}

	public static void main(String[] args) {
                // At first, parse the unified diff file and get the patch
		Patch patch = DiffUtils.parseUnifiedDiff(fileToLines("example.diff"));
                
                // Then apply the computed patch to the given text
                List result = DiffUtils.patch(original, patch);
                /// Or we can call patch.applyTo(original). There is no difference.
	}
}

Task 3: Compute the difference between to texts and print it in human-readable side-by-side view

Solution:

Coming soon...