第一章 静态方法 Lambda 作为函数传递

容器：List<People> result=new ArrayList<>();
构造参数： List<People> company=Arrays.asList(new People("Bob", 20),
                                            new People("Allen", 25),
                                            new People("Crystal", 30));
容器遍历方法： for (People people:company)
容器添加方法：result.add(people);

传递方法格式：fIlterPeoples(company, FilteringPeoples::isOldPeole);

传递lambda格式：fIlterPeoples(company, (People p)->p.getAge()>25)

方法使用：
      接受形式：fIlterPeoples(List<People> company,Predicate<People> p)
      使用格式：p.test(people)
      固定部分Predicate<Xxxx> xxx 
              xxx.test(Xxx的实例)

构造三个对象按条件筛选 1.按年龄 2.按名字开头字母
传递方法实现一遍 传递lambda表达式实现一遍
代码输出：

import java.lang.reflect.Array;
import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.function.Predicate;

public class FilteringPeoples {
    public static void main(String[] args){
        // People p= new People("bob", 20);
        List<People> company=Arrays.asList(new People("Bob", 20),
                                            new People("Allen", 25),
                                            new People("Crystal", 30));
        System.out.println(company);
        
        List<People> oldPeoples=fIlterPeoples(company, FilteringPeoples::isOldPeole);
        System.out.println(oldPeoples);
        List<People> aPeoples=fIlterPeoples(company, FilteringPeoples::isStartswithA);
        System.out.println(aPeoples);

        oldPeoples=fIlterPeoples(company, (People p)->p.getAge()>25);
        System.out.println(oldPeoples);
        aPeoples=fIlterPeoples(company, (People p)->p.getName().startsWith("A"));
        System.out.println(aPeoples);
    }
    public static boolean isOldPeole(People people){
        return people.getAge()>25;
    }
    public static boolean isStartswithA(People people){
        return people.getName().startsWith("A");
    }
    public static List<People> fIlterPeoples(List<People> company,Predicate<People> p){
        List<People> result=new ArrayList<>();
        for (People people:company){
            if(p.test(people)){
                result.add(people);
            }
        }
        return result;
    }

}

 class People{
    String name;
    Integer age;
    public People(String name,Integer age){
        this.name=name;
        this.age=age;
 
    }
    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 String toString(){
        return MessageFormat.format("people name:{0} age:{1}\n", name,age);
    }
 }