java8 新特性 stream 数据流

用于重新封装集合数据，通过使用流式Stream代替常用集合数组

1:forEach

class Employee {
    private Long empno; //员工号
    private String ename; //员工姓名
    private Integer salary; //薪水
    private Integer deptno; //所属部门号
    //此处省略get/set方法、构造方法以及toString方法
}
Employee e1 = new Employee(7369L, "SMITH", 800, 20);
Employee e2 = new Employee(7499L, "ALLEN", 1600, 30);
Employee e3 = new Employee(7521L, "WARD", 1250, 30);
Employee e4 = new Employee(7782L, "CLARK", 2450, 10);
Employee e5 = new Employee(7876L, "ADAMS", 1100, 20);

List employees = Arrays.asList(e1, e2, e3, e4, e5);
forEach方法
forEach方法用于迭代stream流中的每一个元素
employees.stream().forEach(System.out::println);
执行结果：

Employee{empno=7369, ename='SMITH', salary=800, deptno=20}
Employee{empno=7499, ename='ALLEN', salary=1600, deptno=30}
Employee{empno=7521, ename='WARD', salary=1250, deptno=30}
Employee{empno=7782, ename='CLARK', salary=2450, deptno=10}
Employee{empno=7876, ename='ADAMS', salary=1100, deptno=20}

1.collect(toList()) 终止操作