smarter hangman player

src/main/java/com/hangman/HangmanRunner.java

@@ -43,7 +43,7 @@ public static void main(String [] args) throws Exception {
 
         HangmanRunner runner = new HangmanRunner(game,
                 display,
-                new YourPlayer(),
+                new YourPlayer(WordList.words),
                 new SleepTicker());
         runner.run();
     }

src/main/java/com/hangman/players/YourPlayer.java

@@ -1,13 +1,71 @@
 package com.hangman.players;
 import com.hangman.Player;
 
+import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.LinkedList;
 import java.util.List;
+import java.util.regex.Pattern;
+
 
 public class YourPlayer implements Player {
+
+  private final List<Character> charsNotGuessedYet  = new ArrayList<>();
+  private final List<Character> charsAlreadyGuessed = new ArrayList<>();
+
+  private final List<String> wordsList = new ArrayList<>();
+
+
+  public YourPlayer(String[] wordsList) {
+    // initialize non-guessed characters
+    for (char c = 'a'; c <= 'z'; ++c) {
+      this.charsNotGuessedYet.add(c);
+    }
+
+    // copy the word list
+    this.wordsList.addAll(Arrays.asList(wordsList));
+  }
+
   @Override
   public char GetGuess(List<Character> currentClue) {
-    return 'a';
+    Character guess = null;
+
+    StringBuilder pattern = new StringBuilder(currentClue.size());
+    int nextYetUnknownCharacterIndex = 0;
+    int i = 0;
+    for (Character c : currentClue) {
+      if (c.equals('_')) {
+        nextYetUnknownCharacterIndex = i;
+        pattern.append(".");
+      } else {
+        // known character, act like if it was already guessed
+        this.charsNotGuessedYet.remove(c);
+        this.charsAlreadyGuessed.add(c);
+        pattern.append(c);
+      }
+      ++i;
+    }
+    Pattern wordPattern = Pattern.compile(pattern.toString());
+
+    for (String word : this.wordsList) {
+      if ((word.length() == currentClue.size()) && wordPattern.matcher(word).matches()) {
+        guess = word.charAt(nextYetUnknownCharacterIndex);
+        if (!this.charsAlreadyGuessed.contains(guess)) {
+          break;
+        }
+      }
+    }
+
+    if (guess == null) {
+      // no word matching, just get the next not-yet-guessed character
+      guess = this.charsNotGuessedYet.isEmpty() ?
+              'a' :
+              this.charsNotGuessedYet.get(0);
+    }
+
+    // store char as already guessed
+    this.charsNotGuessedYet.remove(guess);
+    this.charsAlreadyGuessed.add(guess);
+    return guess;
   }
+
 }

src/test/java/com/hangman/players/YourPlayerTest.java

@@ -1,34 +1,57 @@
 package com.hangman.players;
 
 import org.junit.Test;
+
 import java.util.Arrays;
+
 import static org.junit.Assert.assertEquals;
 
 public class YourPlayerTest {
+
+    private static final String[] wordsForTest = {
+        "abc",
+        "acc",
+        "something_longer",
+        "somethingshorter"
+    };
+
+
     @Test
-    public void GuessesAWhenThereAreNoSuccessfulCharactersGuessedYet() {
-        YourPlayer player = new YourPlayer();
+    public void GuessesWhenThereAreNoSuccessfulCharactersGuessedYet() {
+        YourPlayer player = new YourPlayer(wordsForTest);
 
-        char guess = player.GetGuess(Arrays.asList('_', '_', '_'));
+        // last character of the first 3 chars long word
+        char shortGuess = player.GetGuess(Arrays.asList('_', '_', '_'));
+        assertEquals('c', shortGuess);
 
-        assertEquals('a', guess);
+        // last character of the first 16 chars long word
+        char longGuess = player.GetGuess(Arrays.asList('_', '_', '_', '_', '_', '_', '_', '_', '_', '_', '_', '_', '_', '_', '_', '_'));
+        assertEquals('r', longGuess);
     }
 
     @Test
-    public void GuessesAWhenThereAreSuccessfulCharactersGuessedThatAreNotA() {
-        YourPlayer player = new YourPlayer();
+    public void GuessesWhenThereAreSuccessfulCharactersGuessedAndThereIsNoMatchingKnownWord() {
+        YourPlayer player = new YourPlayer(wordsForTest);
 
-        char guess = player.GetGuess(Arrays.asList('m', '_', 'n'));
+        char guess1 = player.GetGuess(Arrays.asList('m', '_', 'n'));
+        assertEquals('a', guess1);
+    }
 
-        assertEquals('a', guess);
+    @Test
+    public void GuessesWhenThereAreSuccessfulCharactersGuessedAndThereIsAMatchingKnownWord() {
+        YourPlayer player = new YourPlayer(wordsForTest);
+
+        char guess2 = player.GetGuess(Arrays.asList('a', '_', 'b'));
+        assertEquals('c', guess2);
     }
 
     @Test
-    public void GuessesAWhenAIsThereAreAsInTheClueAsWell() {
-        YourPlayer player = new YourPlayer();
+    public void GuessesFirstCharacterOfACompleteClue() {
+        YourPlayer player = new YourPlayer(wordsForTest);
 
-        char guess = player.GetGuess(Arrays.asList('_', 'a', '_'));
+        char guess = player.GetGuess(Arrays.asList('a', 'b', 'c'));
 
         assertEquals('a', guess);
     }
+
 }