使用Lamda表达式、stream流遍历Map、list

List<String> list = new ArrayList<String>();
    Map<String,String> map = new HashMap<>();
    map.put("id","11");
    map.put("name","zhangsan");
    map.put("age","30");
    //遍历map集合
    map.forEach((k,v) -> list.add(v));
    //这几种遍历list集合的方法都可以
    list.stream().forEach(System.out::println);
    list.stream().forEach(e-> System.out.println(e));
    list.forEach(e-> System.out.println(e));

List<String> ipList = Lists.newArrayList();
List<OpsResourceTreeSelect> ops = this.parentNodeTree();
ops.forEach(obj -> ipList.add(obj.getIp()));
或者    
List<OpsResourceTreeSelect> ops = this.parentNodeTree();
List<String> ips = ops.stream().map(OpsResourceTreeSelect::getIp).collect(Collectors.toList());

List<OpsResourceList> ops = opsResourceListMapper.selectOpsResourceListList(null);
List<String> ips = ops.stream()
      .filter(obj -> StringUtils.isNotBlank(obj.getIp()))
      .map(OpsResourceList::getIp)
      .distinct()
      .collect(Collectors.toList());

[66.3.125.44, 66.10.113.8, 66.10.113.9, 66.3.125.45, 66.66.66.66, 32.1.52.6, 66.10.113.10, 66.3.125.31, 66.3.125.35, 66.3.125.36]