Java中如何使用StreamCollectors收集器-创新互联

Java中如何使用Stream Collectors收集器？很多新手对此不是很清楚，为了帮助大家解决这个难题，下面小编将为大家详细讲解，有这方面需求的人可以来学习下，希望你能有所收获。

Collectors.toMap:

Student studentA = new Student("20190001","小明");
    Student studentB = new Student("20190002","小红");
    Student studentC = new Student("20190003","小丁");


    //Function.identity() 获取这个对象本身，那么结果就是Map 即 id->student
    //串行收集
   Stream.of(studentA,studentB,studentC)
        .collect(Collectors.toMap(Student::getId,Function.identity()));

    //并发收集
    Stream.of(studentA,studentB,studentC)
        .parallel()
        .collect(Collectors.toConcurrentMap(Student::getId,Function.identity()));

    //================================================================================

    //Map 即 id->name
    //串行收集
    Stream.of(studentA,studentB,studentC)
        .collect(Collectors.toMap(Student::getId,Student::getName));

    //并发收集
    Stream.of(studentA,studentB,studentC)
        .parallel()
        .collect(Collectors.toConcurrentMap(Student::getId,Student::getName));