Question

Iterator<Account> entitiesItr = entities.iterator();
List<AccountSync> accountsList = new ArrayList<AccountSync>();
AccountSync accountsync = new AccountSync();
while (entitiesItr.hasNext()) {
    Account account = (Account) entitiesItr.next();
    accountsync.setAccountName(account.getName());
    accountsList.add(accountsync);
    System.out.println("1st-name->"+account.getName());
}

Iterator<AccountSync> it = accountsList.iterator();
while (it.hasNext()) {
    AccountSync accountSync2 = (AccountSync) it.next();
    System.out.println("2nd-name->"+accountSync2.getAccountName());
        }

输出：

1st-name->Sun
1st-name->Oracle
1st-name->google
...
1st-name->Yahoo



2nd-name->Yahoo
2nd-name->Yahoo
2nd-name->Yahoo
2nd-name->Yahoo
....50 times

第二-名称 - ＆GT;仅打印最后一行50次，而1st-name-＆gt;它打印所有50行。为什么会这样？

Answer 1

这是因为第一个循环会覆盖相同的AccountSync。试试这种方式：

AccountSync accountsync;
while (entitiesItr.hasNext()) {
    accountsync = new AccountSync();
    Account account = (Account) entitiesItr.next();
    accountsync.setAccountName(account.getName());
    accountsList.add(accountsync);
    System.out.println("1st-name->"+account.getName());
}

在这种情况下，每个实体都将拥有自己的AccountSync实例。

Answer 2

你需要搬家

AccountSync accountsync = new AccountSync();

到你的while循环内部，否则你使用相同的一个并只是更新它。

List iterator仅返回最后一行

2 个答案: