代码：

import java.util.ArrayList;
import java.util.Arrays;

public class practice{
    public static void main(String[] args) {
        ArrayList<Phone> list = new ArrayList<>();
        Phone p1 = new Phone("小米",1000);
        Phone p2 = new Phone("苹果",8000);
        Phone p3 = new Phone("锤子",2999);
        list.add(p1);
        list.add(p2);
        list.add(p3);
        ArrayList<Phone> phoneList = func(list);
        for(int i=0;i<phoneList.size();i++){
            Phone phone = phoneList.get(i);
            System.out.println(phone.getBrand()+","+phone.getPrice());
        }

    }
    public static ArrayList<Phone> func(ArrayList<Phone>list){
        //定义一个集合
        ArrayList<Phone> resultlist = new ArrayList<>();
        for(int i=0;i<list.size();i++){
            Phone p = list.get(i);
            double price = p.getPrice();
            if(list.get(i).getPrice()<3000){
                resultlist.add(p);
            }
        }
        return resultlist;
    }
}

public class Phone{
    private String brand;
    private double price;

    public Phone() {
    }

    public Phone(String brand, double price) {
        this.brand = brand;
        this.price = price;
    }

    public String getBrand() {
        return brand;
    }

    public void setBrand(String brand) {
        this.brand = brand;
    }

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }
}

结果：

如果在方法中打印元素的话，虽然也可以实现输出符合条件的元素，但是后续如果要使用就不方便。