Java中快速对列表排序去重、排序

初始物料数据

List list = new ArrayList<>();
list.add("all");
list.add("dfg");
list.add("bnm");
list.add("cff");
list.add("uii");
list.add("uii");

作用： 去重

System.out.println(list);
Set set = new HashSet<>(list);
System.out.println(set);

结果：

[all, dfg, bnm, cff, uii, uii]
[all, bnm, cff, dfg, uii]

作用： 排序去重

System.out.println(list);
Set tree = new TreeSet<>(list);
System.out.println(tree);

结果：

[all, dfg, bnm, cff, uii, uii]
[all, bnm, cff, dfg, uii]

作用： 排序去重

System.out.println(list);
List collect = list
           .stream() // 得到流
           .distinct() // 去重
           .sorted() // 自然排序
           .collect(Collectors.toList());//收集并返回
System.out.println(collect);

结果：

[all, dfg, bnm, cff, uii, uii]
[all, bnm, cff, dfg, uii]

根据AddMonitorGetWbsVO对象中的wbsId属性去重

方法1：

public List getWbsProject(AddMonitorGetWbsDTO dto) {
    List monitorWbsProject = riskSourcesMapper.getMonitorWbsProject(dto);
    return monitorWbsProject.stream().collect(
            collectingAndThen(toCollection(() -> new TreeSet<>(Comparator.comparing(AddMonitorGetWbsVO::getWbsId))), ArrayList::new));
}

方法2：

public List getWbsProject(AddMonitorGetWbsDTO dto) {
    List monitorWbsProject = riskSourcesMapper.getMonitorWbsProject(dto);
	return monitorWbsProject.stream()
		.filter(distinctByKey(AddMonitorGetWbsVO::getWbsId)).collect(Collectors.toList());
}


public static  Predicate distinctByKey(Function keyExtractor) {
    Map seen = new ConcurrentHashMap<>();
    return t -> seen.putIfAbsent(keyExtractor.apply(t), Boolean.TRUE) == null;
}