策略模式->Lambda表达式->Steam API

/**
 * 员工对象
 */
public class Employ {

    private String name;
    private Integer age;
    private Double salary;

    public Employ() {
    }

    public Employ(String name, Integer age, Double salary) {
        this.name = name;
        this.age = age;
        this.salary = salary;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public Double getSalary() {
        return salary;
    }

    public void setSalary(Double salary) {
        this.salary = salary;
    }

    @Override
    public String toString() {
        return "Employ{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", salary=" + salary +
                '}';
    }
}

/**
 * 过滤接口
 */
public interface MyPredict {

    boolean test(T t);

}

/**
 * 不同种实现策略
 */
public class FileEmployByAge implements MyPredict {
    @Override
    public boolean test(Employ employ) {
        return employ.getAge() >= 35;
    }
}

public class Test {

    private static List list = Arrays.asList(new Employ("张三",18,99999.9),
            new Employ("李四",18,3439.9),
            new Employ("王五",36,6666.9),
            new Employ("赵六",41,7777.9),
            new Employ("田七",9,2222.9));

    public static void main(String[] args) {
        // 获取当前公司中员工中年龄大于35的员工信息
//        List employs = filterEmploys(list);
//        for (Employ employ:employs) {
//            System.out.println(employ);
//        }

        // 获取当前公司中员工中工资大于5000的工资信息
//        List employs1 = filterEmploys2(list);
//        for (Employ employ:employs1) {
//            System.out.println(employ);
//        }

        // 优化方式一 策略模式
//        List employs = fileEmploy(list, new FileEmployByAge());
//        for (Employ employ:employs) {
//            System.out.println(employ);
//        }

        // 优化方式二 匿名内部类
//        List employs = fileEmploy(list, new MyPredict() {
//            @Override
//            public boolean test(Employ employ) {
//                return employ.getSalary() < 5000;
//            }
//        });
//        for (Employ employ:employs) {
//            System.out.println(employ);
//        }

        // 优化方式三 Lambda表达式
//        List employs = fileEmploy(list, t -> t.getAge() > 35);
//        employs.forEach(System.out::println);

        // 优化方式四 Stream API
        list.stream()
                .filter(t->t.getAge()>35)
                .limit(1)
                .forEach(System.out::println);

        list.stream()
                .map(Employ::getName)
                .forEach(System.out::println);

    }

    // 优化方式一
    public static List fileEmploy(List list,MyPredict myPredict){
        List list1 = new ArrayList<>();
        for (Employ employ:list) {
            if (myPredict.test(employ)){
                list1.add(employ);
            }
        }
        return list1;
    }

    // 获取当前公司中员工中工资大于5000的工资信息
    public static List filterEmploys2(List list){
        List list1 = new ArrayList<>();
        for (Employ employ:list) {
            if (employ.getSalary() >= 5000){
                list1.add(employ);
            }
        }
        return list1;
    }

    // 获取当前公司中员工中年龄大于35的员工信息
    public static List filterEmploys(List list){
        List list1 = new ArrayList<>();
        for (Employ employ:list) {
            if (employ.getAge() >= 35){
                list1.add(employ);
            }
        }
        return list1;
    }

}