如何比较两个文本文件的内容并在另一个文本文件中输出？ 文字1-文字2

Question

i want to do the content of 1.txt minus 2.txt and output that in 3.txt. Also if 2.txt has extra remaining lines, output it in 4.txt.

The content of the text files are not ordered line by line, so basically the code needs to remove the matching line only, like this:

1.txt contains:

example1
example2
example3

2.txt contains:

example2
example3
example4

3.txt will contain:

example1

4.txt will contain:

example4

Answer 1

Using Guava :

Set<String> lines1 = 
    new HashSet<>(Files.readLines(new File("1.txt"), Charsets.UTF_8));
Set<String> lines2 = 
    new HashSet<>(Files.readLines(new File("2.txt"), Charsets.UTF_8));
Set<String> minus1 = Sets.difference(lines1, lines2);
Set<String> minus2 = Sets.difference(lines2, lines1);
Files.asCharSink(new File("3.txt"), Charsets.UTF_8).writeLines(minus1);
Files.asCharSink(new File("4.txt"), Charsets.UTF_8).writeLines(minus2);