读取JDK API文档，并根据单词出现频率排序

1，拿到 API 文档

登录 https://docs.oracle.com/javase/8/docs/api/ ，

选中特定的类，然后 copy 其中的内容，

放入 TXT 文件中 ，

2，读取TXT内容，并排序

package com.lgx.test;

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

public class ReadVectorAPI {

public static String filename = "src/Vector.txt";
public static StringBuffer sb = null;

public static void main(String[] args) {
try {
//根据单词字母排序
countWordOrderByWord();
//根据单词频率排序
countWordOrderByCount();
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}

// 计算单词的出现次数,依据单词排序
public static void countWordOrderByWord() throws FileNotFoundException {
BufferedReader br = null;
try {
br = new BufferedReader(new FileReader(new File(filename)));
String inputLine = null;
TreeMap<String, Integer> map = new TreeMap<String, Integer>();
while ((inputLine = br.readLine()) != null) {
String[] words = inputLine.split("[ \n\t\r.,;:!?(){}]");
for (int i = 0; i < words.length; i++) {
String key = words[i].toLowerCase();
if (key.length() > 0) {
if (map.get(key) == null) {
map.put(key, 1);
} else {
int times = map.get(key).intValue();
times++;
map.put(key, times);
}
}
}
}
Set<Map.Entry<String, Integer>> entrySet = map.entrySet();
System.out.println("=====根据单词字母排序=====");
for (Map.Entry<String, Integer> entry : entrySet) {
System.out.println(entry.getKey() + " 在API文档中出现了 " + entry.getValue() + " 次");
}
} catch (IOException e) {
e.printStackTrace();
}
}

// 计算单词的出现次数,依据次数排序
public static void countWordOrderByCount() throws FileNotFoundException {
BufferedReader br = null;
try {
br = new BufferedReader(new FileReader(new File(filename)));
String inputLine = null;
TreeMap<String, Integer> map = new TreeMap<String, Integer>();
while ((inputLine = br.readLine()) != null) {
String[] words = inputLine.split("[ \n\t\r.,;:!?(){}]");
for (int i = 0; i < words.length; i++) {
String key = words[i].toLowerCase();
if (key.length() > 0) {
if (map.get(key) == null) {
map.put(key, 1);
} else {
int times = map.get(key).intValue();
times++;
map.put(key, times);
}
}
}
}

List<Map.Entry<String, Integer>> list = new ArrayList<Map.Entry<String, Integer>>(map.entrySet());
Collections.sort(list, new Comparator<Map.Entry<String, Integer>>() {
public int compare(Entry<String, Integer> o1, Entry<String, Integer> o2) {
return o2.getValue().compareTo(o1.getValue());
}
});
System.out.println("=====根据单词频率排序=====");
for (Map.Entry<String, Integer> mapping : list) {
System.out.println(mapping.getKey() + " 在API文档中出现了 " + mapping.getValue() + " 次");
}
} catch (IOException e) {
e.printStackTrace();
}
}
}

输出结果前部分截图为；