java - 从 map 中检索第一个和第二个值

Question

从 map 中获取第一个值和第二个值的最佳方法是什么。我正在尝试读取 tableLists map 并从 map 中获取第一个和第二个值。

下面是我的代码，其中 ReadTableConnectionInfo 是类。

private final LinkedHashMap<String, ReadTableConnectionInfo> tableLists;

ReadTableConnectionInfo table = tablePicker();


private ReadTableConnectionInfo tablePicker() {

    Random r = new SecureRandom();
    ReadTableConnectionInfo table;

    if (r.nextFloat() < Read.percentageTable / 100) {
        table = get first value from tableLists map
    } else {
        table = get second value from tableLists map
    }

    return table;
}

Answer 1

假设您确定 LinkedHashMap 至少包含两个值，您可以这样做:

Iterator<Map.Entry<String, ReadTableConnectionInfo >> it = tableLists.entrySet().iterator();
if (r.nextFloat() < Read.percentageTable / 100) {
  table = it.next().getValue();
} else { //since you have an else, you have to re-ignore the first value just below
  it.next(); // ignoring the first value
  table = it.next().getValue(); //repeated here in order to get the second value
}