【发布时间】：2018-12-02 11:20:59
【问题描述】：
是否可能/正确（to）或使用lambda重写下面的内容？这里我提供了 KeyMapper 和 ValueMapper Function 的内联实现。
public Map<Integer, List<Employee>> getSubordinateHighestSalEmpMapV1(List<Employee> employees) {
return employees.stream()
.filter(e -> e.getSubordinates() != null)
.collect(Collectors.toMap( //keyMapper
new Function<Employee, Integer>() {
@Override
public Integer apply(Employee t) {
return t.getId();
}
},
new Function<Employee, List<Employee>>() {//valueMapper
@Override
public List<Employee> apply(Employee t) {
List<Employee> subordinates = t.getSubordinates();
List<Employee> subOrdinatesListWithHighestSalary = new ArrayList<>();
int maxSal = Integer.MIN_VALUE;
for(Employee s: subordinates) {
if(s.getSalary() >= maxSal) {
maxSal = s.getSalary();
}
}
for(Employee s: subordinates) {
if(s.getSalary() == maxSal) {
subOrdinatesListWithHighestSalary.add(s);
}
}
return subOrdinatesListWithHighestSalary;
}
}));
}
我要达到什么目标：
员工类有List<Employee> subordinates。我试图在每个员工下的下属中获得最高薪水。每个员工可能有也可能没有下属。如果下属不存在，则不包括在结果中。如果多个下属具有相同的最高薪水，则所有下属都应出现在结果中。
例如，在每个部门中获得最高薪的员工（员工，如果薪水匹配）是类似的。
Employee.java
import java.util.List;
public class Employee{
private int id;
private int salary;
private List<Employee> subordinates;
private String name;
private int age;
public int getId() {
return id;
}
public Employee setId(int id) {
this.id = id;
return this;
}
public int getSalary() {
return salary;
}
public Employee setSalary(int salary) {
this.salary = salary;
return this;
}
public List<Employee> getSubordinates() {
return subordinates;
}
public Employee setSubordinates(List<Employee> subordinates) {
this.subordinates = subordinates;
return this;
}
public String getName() {
return name;
}
public Employee setName(String name) {
this.name = name;
return this;
}
public int getAge() {
return age;
}
public Employee setAge(int age) {
this.age = age;
return this;
}
@Override
public String toString() {
return "Employee [id=" + id + ", salary=" + salary + ", name=" + name
+ ", age=" + age + "]";
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + id;
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
Employee other = (Employee) obj;
if (id != other.id)
return false;
return true;
}
}
例如下面的输入：
- employee1(id:100) 有employee2,employee3,employee4 和其中 employee3支付最高的30000，应该是产出的一部分
- employee2(id:101) 有employee5、employee6，其中employee5 的薪水最高，20000，应该是其中的一部分输出
- employee3(id:102) 得到了employee7 和employee8，两者的工资相同为16000，输出应该两者都包含。
-
employee8(id:107) 有一个下属employee9，工资为12000，employee9 应该是输出的一部分
下面的输入如上所述：
private static List<Employee> getEmployeeListV1() { int i = 100; Employee employee1 = (Employee) new Employee().setId(i++).setSalary(10000).setAge(101).setName("emp 1"); Employee employee2 = (Employee) new Employee().setId(i++).setSalary(20000).setAge(110).setName("emp 2"); Employee employee3 = (Employee) new Employee().setId(i++).setSalary(30000).setAge(20).setName("emp 3"); Employee employee4 = (Employee) new Employee().setId(i++).setSalary(10000).setAge(32).setName("emp 4"); Employee employee5 = (Employee) new Employee().setId(i++).setSalary(20000).setAge(34).setName("emp 5"); Employee employee6 = (Employee) new Employee().setId(i++).setSalary(15000).setAge(44).setName("emp 6"); Employee employee7 = (Employee) new Employee().setId(i++).setSalary(16000).setAge(56).setName("emp 7"); Employee employee8 = (Employee) new Employee().setId(i++).setSalary(16000).setAge(65).setName("emp 8"); Employee employee9 = (Employee) new Employee().setId(i++).setSalary(12000).setAge(74).setName("emp 9"); employee1.setSubordinates(Stream.of(employee2,employee3,employee4).collect(Collectors.toList())); employee2.setSubordinates(Stream.of(employee5,employee6).collect(Collectors.toList())); employee3.setSubordinates(Stream.of(employee7,employee8).collect(Collectors.toList())); employee8.setSubordinates(Stream.of(employee9).collect(Collectors.toList())); List<Employee> employees = Stream.of(employee1,employee2, employee3,employee4,employee5, employee6,employee7,employee8, employee9).collect(Collectors.toList()); return employees; }
以下是输出：
100=[Employee [id=102, salary=30000, name=emp 3, age=20]]
101=[Employee [id=104, salary=20000, name=emp 5, age=34]]
102=[Employee [id=106, salary=16000, name=emp 7, age=56], Employee [id=107, salary=16000, name=emp 8, age=65]]
107=[Employee [id=108, salary=12000, name=emp 9, age=74]]
说明：
【问题讨论】：
-
这是一个技巧/建议，当您在 IntelliJ 等 IDE 中键入此类代码时，它会建议您所有可能的清理工作。
-
谢谢@nullpointer，但是，不幸的是我得到了eclipse。
标签： java java-8 java-stream