Anagram Finder

This Java program reads a list of words from an input file and groups them into sets of anagrams. The output of this program is a file named output.txt that lists a word and all its associated anagrams.

How It Works

1. Input: The program takes the path of an input file as a command-line argument. The input file should contain one word per line.
2. Processing:
   • The program normalizes input by removing non-alphabetical characters and converting to lowercase.
   • Words considered for anagrams are at least two characters long. Example: "at" can have the anagram "ta".
   • It sorts the word's characters alphabetically and uses this sorted string as a key to group anagrams.
   • If a key does not exist in our anagram set, add the key and its original unsorted word to set.
   • If multiple words share the same sorted string, they are considered anagrams and added to their lists at their respective keys.
3. Output: After processing all the words, the program writes the anagram groups to a file named output.txt. Each group is formatted as:

   word: [anagram1, anagram2, ...]
   

Requirements

• Java 8 or later.
• An input text file with words (one word per line).
• Terminal or Windows Command Line.

Usage

1. Compile the Java program:

   javac Anagram.java
   

2. Run the program, passing the path to the input file as an argument:

   java Anagram words.txt
   

3. The program will process the input file, find anagram groups, and write them to output.txt.

Example

Input File (input.txt):

eat
tea
tan
ate
nat
bat

Output File (output.txt):

eat: [tea, ate]
tan: [nat]

Error Handling

• If the input file is not found, the program will print an error message.
• If there is an issue with file writing (e.g., permissions), the program will print an appropriate error message.

Code Explanation

Main Method

1. SortedMap for Anagrams:

   • A SortedMap<String, LinkedList<String>> is used to store the anagram groups. The key is a sorted version of the word, and the value is a list of words (anagrams) that match this key.

2. Input File Processing:

   • The program uses a Scanner to read the input file. Each word is cleaned by removing non-alphabetical characters and converting it to lowercase.
   • For non-English alphabetical characters (i.e. étude), this program uses the following regular expression to read in Unicode letters: "[\\p{L}]". The program does not convert non-ASCII letters to ASCII letters.
   • The word is then sorted alphabetically, and the sorted word is used as the key to group anagrams.

3. Writing to Output File:

   • The program opens output.txt for appending.
   • It iterates through the sorted map of anagrams and writes the results to the output file, only including groups with more than one word (true anagram groups).

4. Error Handling:

   • The program includes try-catch blocks to handle FileNotFoundException and IOException.