1.
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。 如果 S 和 T 出现频率都是 10.21%， 那么， S 要排在T 的前面。
package test; import java.io.BufferedReader; import java.io.File; import java.io.FileInputStream; import java.io.InputStreamReader; import java.text.DecimalFormat; import java.util.Scanner; public class test { public static void main(String args[]) { System.out.println("1.统计字母个数以及频率 2.统计所有单词的个数 3.前10个数最多单词"); Scanner sc=new Scanner(System.in); int a=sc.nextInt(); DecimalFormat df = new DecimalFormat("0.00%"); try { char shu[] = new char[100000]; char zimu[] = new char[52]; int j = 0; long count[] = new long [52]; String pathname = "D:\飘c1.txt"; File filename = new File(pathname); InputStreamReader reader = new InputStreamReader(new FileInputStream(filename)); BufferedReader br = new BufferedReader(reader); String line[] = new String[100000]; ; for (int i = 0; i < line.length; i++) { line[i] = br.readLine(); } br.close(); int k = 0; while (line[k] != null) { for (int i = 0; i < line[k].length(); i++) { shu[j] = line[k].charAt(i); j++; } k++; } for (int i = 0; i < shu.length; i++) { switch (shu[i]) { case 'a': zimu[0] = 'a'; count[0]++; break; case 'b': zimu[1] = 'b'; count[1]++; break; case 'c': zimu[2] = 'c'; count[2]++; break; case 'd': zimu[3] = 'd'; count[3]++; break; case 'e': zimu[4] = 'e'; count[4]++; break; case 'f': zimu[5] = 'f'; count[5]++; break; case 'g': zimu[6] = 'g'; count[6]++; break; case 'h': zimu[7] = 'h'; count[7]++; break; case 'i': zimu[8] = 'i'; count[8]++; break; case 'j': zimu[9] = 'j'; count[9]++; break; case 'k': zimu[10] = 'k'; count[10]++; break; case 'l': zimu[11] = 'l'; count[11]++; break; case 'm': zimu[12] = 'm'; count[12]++; break; case 'n': zimu[13] = 'n'; count[13]++; break; case 'o': zimu[14] = 'o'; count[14]++; break; case 'p': zimu[15] = 'p'; count[15]++; break; case 'q': zimu[16] = 'q'; count[16]++; break; case 'r': zimu[17] = 'r'; count[17]++; break; case 's': zimu[18] = 's'; count[18]++; break; case 't': zimu[19] = 't'; count[19]++; break; case 'u': zimu[20] = 'u'; count[20]++; break; case 'v': zimu[21] = 'v'; count[21]++; break; case 'w': zimu[22] = 'w'; count[22]++; break; case 'x': zimu[23] = 'x'; count[23]++; break; case 'y': zimu[24] = 'y'; count[24]++; break; case 'z': zimu[25] = 'z'; count[25]++; break; case 'A': zimu[26] = 'A'; count[26]++; break; case 'B': zimu[27] = 'B'; count[27]++; break; case 'C': zimu[28] = 'C'; count[28]++; break; case 'D': zimu[29] = 'D'; count[29]++; break; case 'E': zimu[30] = 'E'; count[30]++; break; case 'F': zimu[31] = 'F'; count[31]++; break; case 'G': zimu[32] = 'G'; count[32]++; break; case 'H': zimu[33] = 'H'; count[33]++; break; case 'I': zimu[34] = 'I'; count[34]++; break; case 'J': zimu[35] = 'G'; count[35]++; break; case 'K': zimu[36] = 'K'; count[36]++; break; case 'L': zimu[37] = 'L'; count[37]++; break; case 'M': zimu[38] = 'M'; count[38]++; break; case 'N': zimu[39] = 'N'; count[39]++; break; case 'O': zimu[40] = 'O'; count[40]++; break; case 'P': zimu[41] = 'P'; count[41]++; break; case 'Q': zimu[42] = 'Q'; count[42]++; break; case 'R': zimu[43] = 'R'; count[43]++; break; case 'S': zimu[44] = 'S'; count[44]++; break; case 'T': zimu[45] = 'T'; count[45]++; break; case 'U': zimu[46] = 'U'; count[46]++; break; case 'V': zimu[47] = 'V'; count[47]++; break; case 'W': zimu[48] = 'W'; count[48]++; break; case 'X': zimu[49] = 'X'; count[49]++; break; case 'Y': zimu[50] = 'Y'; count[50]++; break; case 'Z': zimu[51] = 'Z'; count[51]++; } } int ci = 0; int sum = 0; System.out.println("短文中各字母出现情况统计如下："); for (int i = 0; i < 26; i++) { count[i]+=count[i+26]; if (count[i] != 0) { ci++; sum += count[i]; } } for(int i=0;i<26;i++) { if(count[i]<count[i+1]) { int c=(int) count[i]; count[i+1]=count[i]; count[i]=c; } System.out.println(ci + ".字母" + zimu[i] + "的出现次数是:" + count[i]); } for (int i = 0; i < 26; i++) { System.out.println(zimu[i]+"出现的百分比为:"+df.format(count[i]*1.0/sum)); } System.out.println("字母共计：" + sum + "个"); } catch (Exception e) { e.printStackTrace(); } } }
2.
输出单个文件中的前 N 个最常出现的英语单词。
package test;
import java.io.BufferedReader;
import java.io.FileReader;
import java.util.*;
public class test1 {
public static void main(String [] args) throws Exception {
BufferedReader br = new BufferedReader(new FileReader("D:/飘c1.txt"));
StringBuffer sb = new StringBuffer();
String text =null;
while ((text=br.readLine())!= null){
sb.append(text);// 将读取出的字符追加到stringbuffer中
}
br.close(); // 关闭读入流
String str = sb.toString().toLowerCase(); // 将stringBuffer转为字符并转换为小写
String[] words = str.split("[^(a-zA-Z)]+"); // 非单词的字符来分割，得到所有单词
Map<String ,Integer> map = new HashMap<String, Integer>() ;
for(String word :words){
if(map.get(word)==null ){ // 若不存在说明是第一次，则加入到map,出现次数为1
map.put(word,1);
}else
{
map.put(word,map.get(word)+1); // 若存在，次数累加1
}
}
// 排序
List<Map.Entry<String ,Integer>> list = new ArrayList<Map.Entry<String,Integer>>(map.entrySet());
Comparator<Map.Entry<String,Integer>> comparator = new Comparator<Map.Entry<String, Integer>>() {
public int compare(Map.Entry<String, Integer> left, Map.Entry<String, Integer> right) {
return (left.getValue().compareTo(right.getValue()));
}
};
// 集合默认升序升序
Collections.sort(list,comparator);
for(int i=0;i<list.size();i++){// 由高到低输出
System.out.println(list.get(list.size()-i-1).getKey() +":"+list.get(list.size()-i-1).getValue());
}
}
}
