java 如何在java中制作二维LinkedList？
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How to make two dimensional LinkedList in java?
提问by iAbdul
for example:
例如：
public static LinkedList<String, Double> ll = new LinkedList<String, Double>;
回答by Kent
from your question, I think (not 100% sure) you are looking for
java.util.LinkedHashMap<K, V>
从你的问题来看，我认为（不是 100% 确定）你正在寻找
java.util.LinkedHashMap<K, V>
in your case, it would be LinkedHashMap<String, Double>
在你的情况下，这将是 LinkedHashMap<String, Double>
from java doc:
来自 java 文档：
Hash table and linked list implementation of the Map interface, with predictable iteration order. This implementation differs from HashMap in that it maintains a doubly-linked list running through all of its entries.
Map接口的哈希表和链表实现，迭代顺序可预测。此实现与 HashMap 的不同之处在于它维护一个双向链表，贯穿其所有条目。
if you do want to get element by list.get(5), you could :
如果您确实想通过 获取元素list.get(5)，您可以：
LinkedList<Entry<String, Double>>
so you can get Entry element by Entry entry = list.get(5), then entry.getKey()gives you the STring, and entry.getValue()gives you the Double.
因此您可以通过 获取 Entry 元素Entry entry = list.get(5)，然后entry.getKey()为您提供字符串，并entry.getValue()为您提供双精度值。
回答by jlordo
Reading all your comments, I suggest you do something like this:
阅读您所有的评论，我建议您执行以下操作：
public class StringAndDouble {
private String str;
private double dbl;
// add constructor
// add getters, setters and other methods as needed.
// override equals() and hashCode()
}
Now you can use:
现在您可以使用：
List<StringAndDouble> list = new LinkedList<>(); // or
List<StringAndDouble> list = new ArrayList<>(); // better in most cases
Now you can access your objects by index.
现在您可以通过索引访问您的对象。
This answer creates a new class, to fit your needs. The class has two fields, one String, one double. This doesn't make the class two dimensional. I think you have a misunderstanding there. When there are ndimensions, you need nindexes to access an element. You were talking of accessing by index, so I assume you're looking for a one dimensional list holding the objects, that have more than one field.
这个答案创建了一个新类，以满足您的需求。该类有两个字段，一String，一double。这不会使类成为二维的。我想你那里有误解。当有n维度时，您需要n索引来访问元素。您说的是按索引访问，所以我假设您正在寻找一个包含多个字段的对象的一维列表。
回答by user949300
Since OP in a comment to @Kent says he wants to be able to get items by index...
由于 OP 在对@Kent 的评论中说他希望能够通过索引获取项目......
Note that a LinkedList(and LinkedHashMap) are inefficientat that. He may prefer an ArrayList. So I would suggest that his "2D" implementation be a
请注意， a LinkedList(和LinkedHashMap)在这方面效率低下。他可能更喜欢ArrayList. 所以我建议他的“2D”实现是一个
ArrayList<Map.Entry<String, Double>>
which will efficiently support a get by index.
这将有效地支持按索引获取。
As for the normal get(String key), you'd have to do a linear search of all the entries, which would be inefficient.
至于 normal get(String key)，您必须对所有条目进行线性搜索，这将是低效的。
So, you have a decision: which way of accessing (by a key or by an index) is more important?
所以，您有一个决定：哪种访问方式（通过键或通过索引）更重要？
回答by Lornikof
You can actually use Linked Lists within eachother... For Example:
您实际上可以在彼此之间使用链表......例如：
public LinkedList<LinkedList<Integer>> twoDimLinkedList = new LinkedList<LinkedList<Integer>>();
Then:
然后：
////////////////
int value = twoDimLinkedList.get(3).get(4);
/////////////////
or (If you were planning on using it for iterative purposes):
或（如果您打算将其用于迭代目的）：
/////////////////
for (int i = 0; i < twoDimLinkedList.size(); i++) {
LinkedList<Integer> twoDimLinkedListRow = new LinkedList<Integer>();
for (int m = 0; m < twoDimLinkedList.get(i).size(); m++) {
twoDimLinkedListRow.add(value);
}
twoDimLinkedList.add(twoDimLinkedListRow);
}
////////////////
回答by Nikola Mitev
Do you mean like this?
你的意思是这样吗？
HashMap<String, Double> hm = new HashMap<String, Double>();
