Java8之集合排序

1,List<Map<String,Object>>格式

这种排序方式有bug,如果item.get(sortField)是数字,toString()之后排序是不正确的

//排序
        Comparator<Map<String, Object>> comparator = Comparator.comparing(item -> item.get(sortField).toString());
        if (Constant.SORT_TYPE_ASC == sortType){
            //升序
            resourceList.sort(comparator);
        }else {
            resourceList.sort(comparator.reversed());
        }

2,List<Model>格式

resultList.sort(Comparator.comparing(MetaDataModel::getOrder));

dictVoList.sort(Comparator.comparingInt(DictVo::getOrder));

3,Set<Model>格式

public static void test2(){
    Set<Student> students = new HashSet<>();
    Student student1 = new Student(1,"李四",1);
    Student student2 = new Student(2,"张三",3);
    Student student3 = new Student(3,"王麻",2);
    students.add(student1);
    students.add(student2);
    students.add(student3);
    List<Student> studentList1 = new ArrayList<>(students);
    studentList1.sort(Comparator.comparing(Student::getAge));
    System.out.println(studentList1);
}

4,Set<String>格式

public static void test3(){
        Set<String> sets = new HashSet<>();
        sets.add("aa");
        sets.add("ee");
        sets.add("cc");
        //倒序
        Set<String> treeSetDesc = new TreeSet<>((o1, o2) -> o2.compareTo(o1));
        treeSetDesc.addAll(sets);
        System.out.println(treeSetDesc);
        //升序
        Set<String> treeSetAsc = new TreeSet<>((o1, o2) -> o1.compareTo(o2));
        treeSetAsc.addAll(sets);
        System.out.println(treeSetAsc);
    }