如何使用 TreeMap java？

Question

I have been writing this line:

Map s_AvailableGameTables = Collection.synchronizedMap(new TreeMap());

And got the following error: cannot find symbol
symbol: method synchronizedMap(java.util.TreeMap) location: interface java.util.Collection

Although I wrote

import java.util.*;
import java.util.TreeMap;
import java.util.Collections;
import java.util.Map;  

What is the reason for that?
Thanks

Answer 1

It's a simple typo. It should be Collections , not Collection .

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Try,

Map s_AvailableGameTables = Collections.synchronizedMap(new TreeMap());

Answer 2

A synchronized TreeMap is rather slow. It's probably better to use ConcurrentSkipListMap if you want a navigatable map that supports concurrency.