It's me, I'm the dummy.
I wrote this program because I like to follow tutorials without copying and pasting. I think typing everything helps me remember what I learn. However, I frequently make transcription errors, realize that copying the tutorial code fixes my problem, and then stare at my code for a really long time trying to figure out where I mistyped.
I thought I'd write a program to make it explicitly clear to myself exactly where my file deviates from the contents of my clipboard because it might save me some time. Then I thought I'd write it in Java because I hate myself.
Something to execute a Java archive with. I suggest OpenJDK.
Download a release. There's one for Linux/macOS and one for Windows.
This should work on any OS so long as you have a Java compiler. All you really need to do is download Comparer.java; the other files aren't necessary unless you want to look at them. Compile it like so:
$ javac Comparer.java
See the release instructions if you downloaded a release. If you compiled Comparer.java yourself, proceed:
Run it with the file you want to test as the first argument, making sure you have the text to test the file against in your clipboard. Say you want to compare your clipboard contents to a file called test.txt in your Documents folder:
$ java Comparer ~/Documents/test.txt
Optionally, you can specify start and end line numbers (inclusive) to only compare a section of your file. So, if you want to check lines 2-14:
$ java Comparer ~/Documents/test.txt 2 14
It will print out a line from your file, a corresponding line from your clipboard, and a line below both with ^ symbols to indicate which characters don't match.
This program separates input by newlines. If you input a line that is too long, it will appear to not be reading your file/clipboard line by line, but it should still give you some idea of where you messed up. If you're using this to compare code, chances are you are not going to be having this problem, since you shouldn't be writing super long lines anyways.