實驗過程

主要思路就是首先將標點符號，常用冠詞等替換掉，然後利用雜湊表和陣列原理排序，輸出最高頻率的前十個陣列

程式碼如下

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

public class test {
 public static void main(String[] args) throws IOException {
  long start = System.currentTimeMillis(); // 程式開始時間
  File file = new File("E:/TEST.txt");

  BufferedReader br = new BufferedReader(new FileReader(file));
  StringBuilder sb = new StringBuilder();
  String line = null;
  while ((line = br.readLine()) != null) {
   sb.append(line);
  }
  br.close(); // 關閉流

  String words = sb.toString(); // 全部的單詞字串
  String targetString = words.replaceAll("[.,\"\\?!:;\\(\\)]", ""); // 將標點替換為空

  // 分詞並且定義英文中不代表實際意義的一些單詞，如介詞、代詞、情態動詞等
  String[] singleWord = targetString.split(" ");
  String[] keys = { "you", "i", "he", "she", "me", "him", "her", "it",
    "they", "them", "we", "us", "your", "your", "our", "his",
    "her", "its", "my", "in", "into", "on", "for", "out", "up",
    "down", "at", "to","too", "with", "by", "about", "among", "between",
    "over", "from", "be", "been", "am", "is", "are", "was", "were",
    "whthout", "the", "of", "and", "a", "an", "that", "this", "be",
    "or", "as", "will", "would", "can", "could", "may", "might",
    "shall", "should", "must", "has", "have", "had", "than" };

  // 將一部分常見的無意義的英語單詞替換為字元 '#' 以便後面輸出單詞出現次數時的判斷
  for (int i = 0; i < singleWord.length; i++) {
   for (String str : keys) {
    if (singleWord[i].equals(str))
     singleWord[i] = "#";
   }
  }

  // 將單詞以及其出現的次數關聯起來
  for (int i = 0; i < singleWord.length; i++) {
   count++; // 計算單詞個數
   if ((wordMap.get(singleWord[i]) != null)) {
    int value = ((Integer) wordMap.get(singleWord[i])).intValue();
    value++;
    wordMap.put(singleWord[i].toLowerCase(), new Integer(value)); // 將單詞轉換為小寫存放以統一格式
   } else {
    wordMap.put(singleWord[i].toLowerCase(), new Integer(1));
   }

  }

  System.out.println("\t\t--檔案資訊--");
  System.out.println("     名稱： " + file.getName() + "    大小： "
    + file.length()/ 1024 + "KB");
  System.out.println("\t\t--檔案資訊--");
  System.out.println();
  System.out.println("■■■■ " + count + " 個單詞中出現頻率最高的 10 個單詞如下■■■■");

  // 比較器， 按值排序
  System.setProperty("java.util.Arrays.useLegacyMergeSort", "true");
  List<Entry<String, Integer>> list = new ArrayList<Entry<String, Integer>>(
    wordMap.entrySet());
  Collections.sort(list, new Comparator<Entry<String, Integer>>() {
   public int compare(Entry<String, Integer> e1,
     Entry<String, Integer> e2) {
    if (e2.getValue() != null && e1.getValue() != null
      && e2.getValue().compareTo(e1.getValue()) > 0) {
     return 1;
    } else {
     return -1;
    }
   }
  });
 
  int wordCount = 1; // 記錄已經輸出單詞的個數
  for (Map.Entry<String, Integer> entry : list) {
   if (entry.getKey().equals("#")) // 相當於過濾作用，不輸出介詞、代詞、情態動詞等無意義單詞
    continue;
   System.out.printf("\t%2d、 %8s \t %4d次\n", wordCount,
     entry.getKey(), entry.getValue());
   if (wordCount++ == 10) { // 表示只輸出10個
    long end = System.currentTimeMillis(); // 程式結束時間
    System.out.println("■■■■■■■■■■■■■■■ 耗時 " + (end - start)
      + " ms" + " ■■■■■■■■■■■■■■■■");
    return;
   }
  }
 }

 private static HashMap<String, Integer> wordMap = new HashMap<String, Integer>();
 private static int count = 0;
}

執行結果如圖

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並且用JDK自帶的visualVM測試工具進行測試，測試見截圖如下