java - 如何在 lambda 表达式中从另一个对象设置一个对象

Question

我从数据库中获取了一个经理列表，现在我必须将此列表的每个对象填充到另一个对象，即员工，并将其作为列表（employeeList）返回给它的调用函数。Manager 和 Employee 都包含相同的字段。我必须使用流的 lambda 表达式来实现这一点。

雇员.java

public class Employee {
private String name;
private String designation;
private String active;

public String getActive() {
    return active;
}
public void setActive(String active) {
    this.active = active;
}
public String getName() {
    return name;
}
public void setName(String name) {
    this.name = name;
}
public String getDesignation() {
    return designation;
}
public void setDesignation(String designation) {
    this.designation = designation;
}}

管理器.java

public class Manager {
private String name;
private String designation;
private String active;
public String getActive() {
    return active;
}
public void setActive(String active) {
    this.active = active;
}
public String getName() {
    return name;
}
public void setName(String name) {
    this.name = name;
}
public String getDesignation() {
    return designation;
}
public void setDesignation(String designation) {
    this.designation = designation;
}}

组件Impl.java

public class ComponentImpl {

public List<Employee> catchAllEmployess () {

    List<Manager> managers = DbOperation.collectManagers(2);
    List<Employee> employees = new ArrayList<>();

    for (Manager manager : managers) {
        Employee employee = new Employee();
        employee.setName(manager.getName());
        employee.setDesignation(manager.getDesignation());
        employee.setActive(manager.getActive());
        employees.add(employee);
    }
    return employees;
}

}

标签： javalambdajava-8java-stream

Answer 1

您可以通过在 Employee 类中包含一个构造函数来简化表达式

Employee(String name, String designation, String active) {
        this.name = name;
        this.designation = designation;
        this.active = active;
    }

然后可以用作

List<Employee> employees = managers.stream()
                .map(manager -> new Employee(manager.getName(), manager.getDesignation(), manager.getActive()))
                .collect(Collectors.toList());