Update TopKWords.java

All has been improved according to your advice.

Others/TopKWords.java

@@ -1,11 +1,62 @@
-import  java.io.*;
+import java.io.*;
-import  java.util.*;
+import java.util.*;
 
-/* display the most frequent K words in the file and the times it appear 
+/* display the most frequent K words in the file and the times it appear
     in the file – shown in order (ignore case and periods) */
 
-public   class  TopKWords {
+public class TopKWords {
-    public static void main(String[] a) {
+    static class CountWords {
+        private String fileName;
+
+        public CountWords(String fileName) {
+            this.fileName = fileName;
+        }
+
+        public Map<String, Integer> getDictionary() {
+            Map<String, Integer> dictionary = new HashMap<>();
+            FileInputStream fis = null;
+
+            try {
+
+                fis = new FileInputStream(fileName);  // open the file
+                int in = 0;
+                String s = new String();  // init a empty word
+                in = fis.read();  // read one character
+
+                while (-1 != in) {
+                    if (Character.isLetter((char)in)) {
+                        s += (char)in;  //if get a letter, append to s
+                    } else {
+                        // this branch means an entire word has just been read
+                        if (s.length() > 0) {
+                            // see whether word exists or not
+                            if (dictionary.containsKey(s)) {
+                                // if exist, count++
+                                dictionary.put(s, dictionary.get(s) + 1);
+                            } else {
+                                // if not exist, initiate count of this word with 1
+                                dictionary.put(s, 1);
+                            }
+                        }
+                        s = ""; // reInit a empty word
+                    }
+                    in = fis.read();
+                }
+                return dictionary;
+            } catch (IOException e) {
+                e.printStackTrace();
+            } finally {
+                try {
+                    // you always have to close the I/O streams
+                    fis.close();
+                } catch (IOException e) {
+                    e.printStackTrace();
+                }
+            }
+            return null;
+        }
+    }
+    public static void main(String[] args) {
         // you can replace the filePath with yours
         CountWords cw = new CountWords("/Users/lisanaaa/Desktop/words.txt");
         Map<String, Integer> dictionary = cw.getDictionary();  // get the words dictionary: {word: frequency}
@@ -19,74 +70,15 @@ public   class  TopKWords {
         );
 
         Scanner input = new Scanner(System.in);
-        Integer k = new Integer(input.nextLine());
+        int k = input.nextInt();
         while (k > list.size()) {
             System.out.println("Retype a number, your number is too large");
             input = new Scanner(System.in);
             k = new Integer(input.nextLine());
         }
-        for (int i = 0; i<k; i++) {
+        for (int i = 0; i < k; i++) {
-            System.out.println(list.get(list.size()-i-1));
+            System.out.println(list.get(list.size() - i - 1));
         }
     }
 }
 
-class  CountWords {
-    private String fileName;
-
-    public CountWords(String fileName) {
-        this.fileName = fileName;
-    }
-
-    public Map<String, Integer> getDictionary() {
-        Map<String, Integer> dictionary = new HashMap<>();
-        FileInputStream fis = null;
-
-        try {
-
-            fis = new FileInputStream(fileName);  // open the file
-            int in = 0;
-            StringBuffer sb = new StringBuffer();  // load the word
-            in = fis.read();  // read one character
-            boolean notEnd = true;  // signal whether is the end of file
-
-            while (notEnd) {
-                // when in == -1 means get the end of the file
-                if (-1 == in) {
-                    notEnd = false;  //if false, end the while loop
-                }
-                if (Character.isLetter((char)in)) {
-                    sb.append((char)in);  //if get a letter, put it in StringBuffer
-                } else {
-                    // this branch means an entire word has just been read
-                    if (sb.length() > 0) {
-                        //see whether word exists in StringBuffer or not
-                        if (dictionary.containsKey(sb.toString())) {
-                            //if exist, count++
-                            dictionary.put(sb.toString(), dictionary.get(sb.toString()) + 1);
-                        } else {
-                            // if not exist, initiate count of this word with 1
-                            dictionary.put(sb.toString(), 1);
-                        }
-                    }
-                    sb = new StringBuffer(); //reload the StringBuffer
-                }
-                in = fis.read(); //read the character
-            }
-            return dictionary;
-        }
-        catch (IOException e) {
-            e.printStackTrace();
-        }
-        finally {
-            try {
-                // you always have to close the I/O streams
-                fis.close();
-            }
-            catch (IOException e) {
-                e.printStackTrace();
-            }
-        }
-        return null;
-    }
-}