java - 将对象添加到 ArrayList 将对象值设置为 null

Question

我有一个 Retrofit 请求，它从我的 API 请求 GroupAccount 对象的列表。 API 毫无问题地返回所有值，因此我尝试在 Activity 中循环响应，这会完美地检索值，但是一旦我调用

//groupAccounts is my list, declared and initialised globally, groupAccount is the object I create at the end of each iteration
groupAccounts.add(groupAccount);

它将所有 groupAccount 对象值设置为 null。为什么会发生这种情况？

GroupAccount 模型类中的构造函数:

public GroupAccount(long groupAccountId,
                  long adminId,
                  String accountName,
                  String accountDescription,
                  int numberOfMembers,
                  BigDecimal totalAmountPaid,
                  BigDecimal totalAmountOwed,
                  int testResourceId) {

}

带有onResponse & onFailure的请求方法:

public void getUserAssociatedAccounts(String userId){
Call<List<GroupAccount>> call = apiInterface.getUserAssociatedAccounts(userId);
call.enqueue(new Callback<List<GroupAccount>>() {
  @Override
  public void onResponse(Call<List<GroupAccount>> call, Response<List<GroupAccount>> response) {
    if(!response.isSuccessful()) {
      //Handle
    } else {
      if(response.body().size() > 0){
        for(int i=0; i<response.body().size(); i++) {

          //This is just for clarity
          long groupAccountId = response.body().get(i).getGroupAccountId();
          long adminId = response.body().get(i).getAdminId();
          String accountName = response.body().get(i).getAccountName();
          String accountDescription = response.body().get(i).getAccountDescription();
          int numberOfMembers = response.body().get(i).getNumberOfMembers();
          BigDecimal amountPaid = response.body().get(i).getTotalAmountPaid();
          BigDecimal amountOwed = response.body().get(i).getTotalAmountOwed();
          int testRes = R.drawable.human_photo;

          //Value setting works fine
          GroupAccount groupAccount = new GroupAccount(groupAccountId,
              adminId,
              accountName,
              accountDescription,
              numberOfMembers,
              amountPaid,
              amountOwed,
              testRes);

          //Values are now null here???
          groupAccounts.add(groupAccount);
        }
        setUpFAB();
        setUpNavDrawer();
        setUpAccountPreviewRecyclerView();
        emptyRVTextViewSetUp(checkIfListIsEmpty(groupAccounts));
      }
    }
  }

  @Override
  public void onFailure(Call<List<GroupAccount>> call, Throwable t) {

  }
});

}

我的列表在类(class)开始时是这样设置的:

public class Home extends AppCompatActivity {

List<GroupAccount> groupAccounts = new ArrayList<>();
.
...rest of class
.
}

Answer 1

您尚未在构造函数中设置对象

您的代码:

public GroupAccount(long groupAccountId,
                  long adminId,
                  String accountName,
                  String accountDescription,
                  int numberOfMembers,
                  BigDecimal totalAmountPaid,
                  BigDecimal totalAmountOwed,
                  int testResourceId) {

}

正确的构造函数:

public GroupAccount(long groupAccountId,
                  long adminId,
                  String accountName,
                  String accountDescription,
                  int numberOfMembers,
                  BigDecimal totalAmountPaid,
                  BigDecimal totalAmountOwed,
                  int testResourceId) {

this.groupAccountId = groupAccountId;
this.adminId = adminId;
this.accountName = accountName;
this.accountDescription = accountDescription;
this.numberOfMembers = numberOfMembers;
this.totalAmountPaid = totalAmountPaid;
this.totalAmountOwed = totalAmountOwed;
this.testResourceId = testResourceId; 
}

来源:Java Contrsuctor