测试

输出某个英文文本文件中 26 字母出现的频率，由高到低排列，并显示字母出现的百分比，精确到小数点后面两位。
字母频率 = 这个字母出现的次数 / （所有A-Z，a-z字母出现的总数）
如果两个字母出现的频率一样，那么就按照字典序排列。

package bianli;

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.InputStreamReader;
import java.text.NumberFormat;

public class ZiMu{

    public class java {

    }
    public static void main(String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream("D:\信1807-5郝子嘉20183684\Harry Potter and the Sorcerer's Stone.txt")));
        int[] count  = new int[26];
   
        char[] c = new char[1];
        int len = br.read(c);
        while(len!=-1) {
           
            if(c[0]<='Z'&&c[0]>='A') {
                int number = c[0];
                count[number-65]++;
//                COUNT[number-65]++;
            }
            if(c[0]<='z'&&c[0]>='a') {
                int number = c[0];
                count[number-97]++;
            }
            len = br.read(c);
        }
        count=Paixu(count);
        Print(count);
        System.out.print(" b.txt文件读取完毕！");
        br.close();
       
    }
    public static int[] Paixu(int[] count)
    {
        int temp;
        int size=count.length;
        for(int i=0;i<size-1;i++)
        {
            for(int j=i+1;j<size;j++)
            {
                if(count[i]<count[j])
                {
                    temp=count[j];
                    count[j]=count[i];
                    count[i]=temp;
                   
                }
            }
        }
        return count;
       
    }
    public static void Print(int[] count) {
        NumberFormat numberFormat = NumberFormat.getInstance();
        
        // 设置精确到小数点后2位
 
        numberFormat.setMaximumFractionDigits(2);

        int sum=0;
        for(int i=0;i<count.length;i++)
        {
            sum=count[i]+sum;
        }
        String[] a=new String[count.length];
        for(int i=0;i<count.length;i++)
        {
             a[i] = numberFormat.format((float) count[i] / (float) sum * 100);
        }
        for(int i=0;i<26;i++) {
            if(count[i]>0) {
                char lowerCase = (char)(i+101);
                System.out.println(lowerCase+"("+count[i]+")"+"("+a[i]+"%)");
            }
        }
       
    }

}

 输出单个文件中的前 N 个最常出现的英语单词。
作用：一个用于统计文本文件中的英语单词出现频率的控制台程序；

package bianli;

import java.io.*;
import java.util.*;
import java.util.Map.Entry;

public class Word
{
     public static int n=0;
     public static void main(String[] args) {
     Scanner input=new Scanner(System.in);
     String s;
     int count=0;
     int num=1;
    
     String file1="D:\\信1807-5郝子嘉20183684\\Harry Potter and the Sorcerer's Stone.txt";
    
     try
     {
       BufferedReader a=new BufferedReader(new FileReader(file1));
      
       StringBuffer c=new StringBuffer();
      
       while((s = a.readLine()) != null)
       {
            
             c.append(s);
       }
     
       String m=c.toString().toLowerCase();
      
       String [] d=m.split("[^a-zA-Z0-9]+");
      
       Map<String , Integer> myTreeMap=new  TreeMap<String, Integer>();
       for(int i = 0; i < d.length; i++) {
          
             if(myTreeMap.containsKey(d[i])) {
                 count = myTreeMap.get(d[i]);
                 myTreeMap.put(d[i], count + 1);
             }
             else {
                 myTreeMap.put(d[i], 1);
             }
         }
    
       List<Map.Entry<String, Integer>> list = new ArrayList<Map.Entry<String, Integer>>(myTreeMap.entrySet());
   
       Collections.sort(list, new Comparator<Map.Entry<String, Integer>>() {
          
             public int compare(Entry<String, Integer> k1, Entry<String, Integer> k2) {
                
                 return k2.getValue().compareTo(k1.getValue());
             }
            
         });
        System.out.println("请输入要输出前N名的N");
         n=input.nextInt();
       for(Map.Entry<String, Integer> map : list) {
             if(num <= n) {
               
                
                 System.out.println(map.getKey() + map.getValue()+"/");
                 num++;
             }
           
           
             else break;
         }
        
         a.close();
        
     }
     catch(FileNotFoundException e)
{
        System.out.println("找不到指定文件");
     }
     catch(IOException e)
     {
         System.out.println("文件读取错误");
     }
     System.out.println("输出完成");
 }
 }