java8简单操作总结

1.抽取listEntity类集合中的一个元素是。list集合
List listStr = list.stream().map(Student::getName).collect(Collectors.toList());
2.抽取list集合A属性是。key值，value值为实体类
Map studentMap = list.stream().collect(Collectors.toMap(Student::getName, student -> student));
3.分组依据属性提取
//准备要分组的集合
List students = Arrays.asList(
new Student(1,“伽罗”,99d),
new Student(2,“后羿”,97d),
new Student(3,“鲁班”,98d),
new Student(4,“后羿”,90d),
new Student(5,“百里”,88d),
new Student(6,“狼狗”,59d),
new Student(7,“艾琳”,78d),
new Student(8,“伽罗”,94d)
);

    //jdk8.0要分组的新功能,按学生姓名分组
    Map> result = new HashMap<>();
    result = students.stream().collect(Collectors.groupingBy(Student::getName));