How to join two string type lists to make a list type of object?

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Suppose I have a class Transaction: 

public class Transaction {

    private String tId;
    private String tStatus;

}

Now I create another class Customer: 

public class Customer {

    private String cId;
    private List<Transaction> transaction;

}

Now, if I get a String list of tIds and a separate String list of tStatus, how do I merge these two lists to make Transaction type List in Java?

java-stream arraylist list arrays java
1 Answers

Assuming Transaction has a constructor from these two strings, and assuming the lists have the same length, you can iterate over both of them and create a list of Transactions:

List<String> tIds = /* probably a method argument? */
List<String> tStatuses = /* probably a method argument? */
if (tIds.size() != tStatuses.size()) {
    throw new IllegalArgumentException("list sizes don't match");
}

List<Transaction> result = new ArrayList<>(tIds.size());
for (int i = 0; i < tIds.size(); ++i) {
    result.add(new Transaction(tIds.get(i), tStatuses.get(i)));
}

Or, arguably more elegantly, use a stream instead of a loop:

List<Transaction> result =
   IntStream.range(0, tIds.size())
            .mapToObj(i -> new Transaction(tIds.get(i), tStatuses.get(i)))
            .collect(Collectors.toList());
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