【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

获取两个txt文档的内容~存储进集合中求集合的并集/交集/补集/差集

 package com.sxd.readLines.aboutDB;

 import java.io.BufferedReader;
 import java.io.BufferedWriter;
 import java.io.File;
 import java.io.FileReader;
 import java.io.FileWriter;
 import java.io.IOException;
 import java.util.HashSet;
 import java.util.Set;

 import com.google.common.collect.Sets;

 public class Test {

     /**
      *
      * @throws IOException
      */

     @org.junit.Test
     public void test1() throws IOException  {
         Set<String> set1 = readFile4List(new File("D:/B/1.txt"));
         Set<String> set2 = readFile4List(new File("D:/B/DB.txt"));

         Set<String> result1 = Sets.union(set1, set2);//合集，并集
         Set<String> result2 = Sets.intersection(set1, set2);//交集
         Set<String> result3 = Sets.difference(set1, set2);//差集 1中有而2中没有的
         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

         //可以分别把4种不同结果 写出文件

         BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(new File("d:/B/result.txt")));
         bufferedWriter.write("共有:"+result1.size()+"条\r\n");
         for (String string : result1) {
             bufferedWriter.write(string+"\r\n");
         }
         bufferedWriter.close();

     }

     public Set<String> readFile4List(File file) throws IOException{
         BufferedReader bufferedReader = new BufferedReader(new FileReader(file));
         Set<String> set = new HashSet<String>();
         String str = null;
         while((str =bufferedReader.readLine()) != null){
             if(str.length() > 6){
                 set.add(str.substring(3));
             }else{
                 set.add(str);
             }

         }
         return set;
     }

 }