基本

Null

import org.apache.commons.collections4.CollectionUtils;
CollectionUtils.isNotEmpty(list);
!(list == null || list.isEmpty());

String字符串

   // str = "2,5,8,7";
   String str = "2,5,8,7";
   List<Integer> idList = StringUtil.stringToList(str,",");

equals

Objects.equals(name, thisName);

String

List<String> list = new ArrayList<String>();
list.add("1");
list.add("2");
list.add("3");
String result = Joiner.on("-").join(list);

Map

实体转MAP

  public static void Test() {
    List<Student> list = new ArrayList<>();
    list.add(new Student(1, "key1", "张"));
    list.add(new Student(2, "key2", "李"));
    Map<String, String> result = list.stream()
            .collect(Collectors.toMap(student -> student.getKey(), Student::getName));
    // result: {key1=zhangsan, key2=lisi}
  }

Consumer

Consumer<String> consumer = (str) -> System.out.println(str);
consumer.accept("Hello Lambda!");
consumer.notify();

Function

Function<String, String> fun = (x) -> x + "/";
fun.apply("s");

DemoStringBuilder Optional

/**
  * 获取 地图服务的名称 和 用户角色的名称
  *
  * @param sysMapAuthEntity
  * @return serverName, roleName
  */
private String[] getServerNameAndRoleName(SysMapAuthEntity sysMapAuthEntity) {
    MapServerEntity mapServerEntity = mapServerService
        .getById(sysMapAuthEntity.getGisMapServerId());
    StringBuilder sb = new StringBuilder();
    Optional<MapServerEntity> serverOpt = Optional.ofNullable(mapServerEntity);
    Consumer<String> slash = x -> sb.append(x + "/");
    serverOpt.map(MapServerEntity::getSvcFolder).ifPresent(slash);
    sb.append(mapServerEntity.getSvcName());
    // _folder_serverName
    String roleName = "_" + sb.toString().replace("/", "_");
    //根据代码获取地图服务器
    return new String[]{sb.toString(), roleName};
}

QueryWrapper

List<User> userList = this.userService.list(
    new QueryWrapper<User>()
            .lambda()
            .ge(User::getAge, 18)
            .likeLeft(User::getName, "ext")
            .eq(User::getEmail, "ext@baomidou.com")
            ...
);