迭代嵌套列表并提取项目

Question

I have the below two list having the data as shown below

the very first list as shown below

storeIdList

 0 = "1"
 1 = "10"
 2 = "12"
 3 = "44"

the second list data is coming is of orderList

 0  ="[1]"
 1  ="[]"
 2  ="[]"
 3= "[46,47]"

so basically each store has certain orders and as shown store 44 has two orders that is 46 and 47 so they are declared as shown below of type string

 List<String> storeIdList
 List<String> orderList

Now basically I want to iterate over a storeList first and from within that store I want to extract the orders with in that store if orders are there for that particular store, for example store 44 has two orders 46 and 47 and store 10 has no orders at all,

so to achieve this I have used two nested for loops

for (int i=0 ; i<storeIdList.size();i++)
 { 
   for (int j=0 ; j<orderList.size();j++)
   {
     // do buisness logic
   }
  } 
   

Now the issue is that for store 44, I am not able to extract both independently that is 46 and 47 please advise how can i extract th orders indepednetly with in the storeId loop

Answer 1

First of all I would not use such data structure, you could use Map<String, List<String>> for example, where key is a store id and value is a list of orders. However, if you are forced to keep the provided structure, you could extract the orders in the following way:

for (int i=0 ; i<storeIdList.size();i++) {
     String storeId = storeIdList.get(i);
     String orders = orderList.get(i);
}

But you should ensure that orderList has the appropriate data.

Answer 2

You can find the corresponding string in orderList using orderList.get(storeIdList.indexOf(storeId)) and then split it on ,\s* after replacing [ and ] with "" , and finally return the resulting String[] .

Note: I have also provided you with a variant of the functions which returns List<String> .

Demo:

import java.util.Arrays;
import java.util.List;

public class Main {

    public static void main(String[] args) {
        List<String> storeIdList = List.of("1", "10", "12", "44");
        List<String> orderList = List.of("[1]", "[]", "[]", "[46,47]");
        System.out.println(storeIdList);
        System.out.println(orderList);

        // Get orderIds for storeId, 44
        System.out.println(Arrays.toString(getOrderIdArray(storeIdList, orderList, "44")));
        System.out.println(getOrderIdList(storeIdList, orderList, "44"));
    }

    static String[] getOrderIdArray(List<String> storeIdList, List<String> orderList, String storeId) {
        return orderList.get(storeIdList.indexOf(storeId))
                        .replace("[", "")
                        .replace("]", "")
                        .split(",\\s*");
    }

    static List<String> getOrderIdList(List<String> storeIdList, List<String> orderList, String storeId) {
        return Arrays.asList(orderList.get(storeIdList.indexOf(storeId))
                                        .replace("[", "")
                                        .replace("]", "")
                                        .split(",\\s*")
                            );
    }
}

Output:

[1, 10, 12, 44]
[[1], [], [], [46,47]]
[46, 47]
[46, 47]

Explanation of the regex, ,\s* at regex101 :

Answer 3

According to your sample lists, there are corresponding store elements and order elements. In other words, the first element of orderList are the orders for the first element of storeIdList . And you want to extract all the orders for each store.

Consider the following.

List<String> storeIdList = List.of("1", "10", "12", "44");
List<String> orderList = List.of("[1]", "[]", "[]", "[46,47]");
for (int i = 0; i < storeIdList.size(); i++) {
    String order = orderList.get(i).replace("[", "").replace("]", "");
    if (order.length() > 0) {
        String[] orders = order.split(",");
        System.out.printf("Store %s orders: %s%n",
                          storeIdList.get(i),
                          java.util.Arrays.toString(orders));
    }
}

First I remove the brackets from the string containing the orders and then I split the resulting string on each comma and thus I get an array where each array element is a single order.

Then you can perform your business logic on the array orders .

When I run the above code, I get the following output:

Store 1 orders: [1]
Store 44 orders: [46, 47]

Answer 4

for(int i=0; i< storeIdList.size() ; i++){
        String[] orderIds = orderIdList.get(i).split(",");
        for(int j = 0; j< orderIds.length ; j++){
            System.out.println("Store Id : "+ i + ", Order Id : " j);
        }
   }

Orderlist can have multiple list, You need to split it to retrieve individually