字符串和集合的转换

String[] arr = str.split(",");
List<String> list = Arrays.asList(arr);

使用Collections.addAll实现

1. List<String> list = new ArrayList<>();
   Collections.addAll(list,str.split(","));
   

转换为int列表

1. Stream.of(str.split(",")).map(String::trim).filter(s->!s.isEmpty()).map(Integer::valueOf).collect(Collectors.toList());
   

Splitter实现

1. <dependency><groupId>com.google.guava</groupId><artifactId>guava</artifactId><version>30.1-jre</version>
   </dependency>List<String> list = Splitter.on(",").splitToList(str);
   

2. 指定输出类型

   1. List<Integer> list = Splitter.on(",").splitToStream(str).map(String::trim).filter(s->!s.isEmpty()).map(Integer::valueOf).collect(Collectors.toList());
      

apache-commons

1. <dependency><groupId>org.apache.commons</groupId><artifactId>commons-collections4</artifactId><version>4.4</version>
   </dependency>List<Integer> list = new ArrayList();
   CollectionUtils.collec(Arrays.asList(str.split(",")),new Transformer<String,Integer>(){@Overridepublic Integer transform(String s){return Integer.valueOf(s);}},list);

2. 流的方式
   List<Integer> list = new ArrayList<>();
   CollectionUtils.collec(Arrays.asList(str.split(",")),Integer::valueOf,list);
   

列表转字符串

1. StringBuilder

   1. StringBuilder builder = new StringBuilder();
      for(String str: list){builder.append(str).append(",");
      }
      String result = builder.substring(0,builder.length()-1);
      

   2. 使用StringBuilder，在单线程环境下，不用加锁，更快

2. String.join

   1. String result = String.join(",",list);
      

   2. 列表必须是字符串列表，如果换成int列表，则不行

3. Guava

   1. String result = Joiner.on(",").join(list);
      

   2. 没有列表类型的限制