after lecture02

02/CountUniqueWords.java

+import java.io.File;
+import java.io.FileNotFoundException;
+import java.util.*;
+/*
+arrays
+lists
+maps (or dictionaries)
+sets
+ */
+
+public class CountUniqueWords {
+    private static final String BOOK_FILENAME = "data/alice.txt";
+
+    public static void main(String[] args) throws FileNotFoundException {
+        //ArrayList<String> ds = new ArrayList<>();
+        HashSet<String> ds = new HashSet<>();
+        //HashMap!
+        Scanner s = new Scanner(new File(BOOK_FILENAME));
+        while (s.hasNext()) {
+            String next = s.next();
+            //if (!ds.contains(next)) {
+                ds.add(next);
+            //}
+        }
+        System.out.println(ds.size());
+    }
+}

02/MostCommonWord.java

+import java.io.File;
+import java.io.FileNotFoundException;
+import java.util.*;
+
+public class MostCommonWord {
+    private static final String BOOK_FILENAME = "data/alice.txt";
+
+    public static void main(String[] args) throws FileNotFoundException {
+        HashMap<String, Integer> ds = new HashMap<>();
+        Scanner s = new Scanner(new File(BOOK_FILENAME));
+        while (s.hasNext()) {
+            String word = s.next();
+            /*
+            if (ds.containsKey(word)) {
+                int whateverwasthere = ds.get(word);
+               ds.put(word, whateverwasthere + 1);
+            }
+            else {
+                ds.put(word, 1);
+            }
+            */
+            /*
+            if (!ds.containsKey(word)) {
+                ds.put(word, 0);
+            }
+            ds.put(word, ds.get(word) + 1);
+             */
+            ds.put(word, 1 + ds.getOrDefault(word, 0));
+            // if word in ds -> add 1
+            // otherwise, set word to 1
+        }
+        // loop through the keys and keep track of the max
+        int max = 0;
+        String word = "";
+        for (String w : ds.keySet()) {
+            if (ds.get(w) > max) {
+                max = ds.get(w);
+                word = w;
+            }
+        }
+        // print the word corresponding to the max
+        System.out.println(word);
+    }
+}
\ No newline at end of file

02/MostCommonWordByChapter.java

+import java.io.File;
+import java.io.FileNotFoundException;
+import java.util.*;
+
+public class MostCommonWordByChapter {
+    private static String BOOK_FILENAME = "data/alice.txt";
+
+    public static void main(String[] args) throws FileNotFoundException {
+                // chapter title
+                                // word  freq
+        HashMap<String, HashMap<String, Integer>> chapters = new HashMap<>();
+        //chapter 1: "the cow goes moo"
+        chapters.put("CHAPTER 1", new HashMap<>());
+        HashMap<String, Integer> inner = chapters.get("CHAPTER 1");
+        inner.put("moo", 1);
+        // XXX: Next line is not necessary
+        chapters.put("CHAPTER 1", inner);
+    }
+}