[Java文件操作] 将素数输出到文件

 1 import java.util.*;
 2 import java.io.*;
 3 
 4 public class SuShu {
 5     final int Max = 100000;
 6     boolean isSu[] = new boolean[Max];
 7     ArrayList<Integer> List = new ArrayList<Integer>();
 8     
 9     public void find() {
10         for (int i = 0; i < Max; i++) {
11             isSu[i] = true;
12         }
13         for (int i = 2; i < Max; i++) {
14             if (isSu[i]) {
15                 List.add(i);
16                 //素数的倍数必然不是素数
17                 for (int x = i + i; x < Max; x = x + i) {
18                     isSu[x] = false;
19                 }
20             }
21         }
22     }
23     
24     public void print() {
25         try {
26             FileWriter fw = new FileWriter("E://data.txt",true);
27             for (int i = 0; i < List.size(); i++){
28                 fw.write(List.get(i)+"\r\n");
29             }
30             fw.flush();
31             fw.close();
32         } catch (IOException e) {
33             e.printStackTrace();
34         }
35     }
36 
37     public static void main(String args[]) {
38         SuShu A = new SuShu();
39         A.find();
40         A.print();
41     }
42 }