java list 转成String数组

Question

List list = shoppingcartDao.selList(userId);查询出来的list，
把list的CommodityId取出来放入数组中，求大神》》》》》（是在select中的）

Answer 1

假想有个Bean类叫Commodity

public class Commodity {

    private String CommodityId;

    public String getCommodityId() {
        return CommodityId;
    }

    public void setCommodityId(String commodityId) {
        CommodityId = commodityId;
    }
} 

如果你的List里面存储的是Commodity对象

public class Main {

    public static void main(String[] args) {

        // 模拟从数据库中取数据 Begin
        List<Commodity> list = new ArrayList<Commodity>();

        Commodity c1 = new Commodity();
        c1.setCommodityId("c1");
        list.add(c1);

        Commodity c2 = new Commodity();
        c2.setCommodityId("c2");
        list.add(c2);

        Commodity c3 = new Commodity();
        c3.setCommodityId("c3");
        list.add(c3);
        // 模拟从数据库中取数据 End

        if (list != null && list.size() > 0) {
            String[] arr = new String[list.size()];

            for (int i = 0; i < arr.length; i++) {
                arr[i] = list.get(i).getCommodityId();
            }

            for (int i = 0; i < arr.length; i++) {
                System.out.println(arr[i]);
            }
        }
    }
}

输出结果

c1
c2
c3