概述

在JDK 1.8裡，可以使用如下程式碼獲取List元素物件中某個屬性的列表。

package test;


import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;

public class ListAttrTest {
    public static void main(String[] args) {
        List<Coupon> couponList = new ArrayList<>();
        Coupon coupon1 =
 
 new Coupon(1,100,"優惠券1");
        Coupon coupon2 = new Coupon(2,200,"優惠券2");
        Coupon coupon3 = new Coupon(3,300,"優惠券3");
        couponList.add(coupon1);
        couponList.add(coupon2);
        couponList.add(coupon3);

        List<Integer> resultList = couponList.stream().map(Coupon::getCouponId)
 
.collect(Collectors.toList());
        System.out.println(resultList);
    }
}

public class Coupon {
    private Integer couponId;
    private Integer price;
    private String name;

    public Coupon(Integer couponId, Integer price, String name) {
        this.couponId = couponId;
        this.price =
 
 price;
        this.name = name;
    }

    public Integer getCouponId() {
        return couponId;
    }

    public void setCouponId(Integer couponId) {
        this.couponId = couponId;
    }

    public Integer getPrice() {
        return price;
    }

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

    public String getName() {
        return name;
    }

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

列印結果如下：

[1, 2, 3]