【Sets】使用Google Guava工程中Sets工具包，实现集合的并集/交集/补集/差集

 1 package com.sxd.readLines.aboutDB;
 2 
 3 import java.io.BufferedReader;
 4 import java.io.BufferedWriter;
 5 import java.io.File;
 6 import java.io.FileReader;
 7 import java.io.FileWriter;
 8 import java.io.IOException;
 9 import java.util.HashSet;
10 import java.util.Set;
11 
12 import com.google.common.collect.Sets;
13 
14 public class Test {
15     
16     /**
17      * 
18      * @throws IOException
19      */
20 
21     @org.junit.Test
22     public void test1() throws IOException  {
23         Set<String> set1 = readFile4List(new File("D:/B/1.txt"));
24         Set<String> set2 = readFile4List(new File("D:/B/DB.txt"));
25         
26         Set<String> result1 = Sets.union(set1, set2);//合集，并集
27         Set<String> result2 = Sets.intersection(set1, set2);//交集
28         Set<String> result3 = Sets.difference(set1, set2);//差集 1中有而2中没有的
29         Set<String> result4 = Sets.symmetricDifference(set1, set2);//相对差集 1中有2中没有  2中有1中没有的 取出来做结果
30         
31         //可以分别把4种不同结果 写出文件
32         
33         BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(new File("d:/B/result.txt")));
34         bufferedWriter.write("共有:"+result1.size()+"条\r\n");
35         for (String string : result1) {
36             bufferedWriter.write(string+"\r\n");
37         }
38         bufferedWriter.close();
39         
40         
41     }
42     
43     public Set<String> readFile4List(File file) throws IOException{
44         BufferedReader bufferedReader = new BufferedReader(new FileReader(file));
45         Set<String> set = new HashSet<String>();
46         String str = null;
47         while((str =bufferedReader.readLine()) != null){
48             if(str.length() > 6){
49                 set.add(str.substring(3));
50             }else{
51                 set.add(str);
52             }
53             
54         }
55         return set;
56     }
57     
58 
59 }