Question

I need to store information in Key Value manner. But the built-in Map interface cannot fit for my requirement. Java Map requires both Key and Values to be reference, while I need to use primitive value as key.

Is there any data structure something like Map ? Thanks for your help!

Requirement Details:

My server written in Java runs as a daemon listening a tcp port. When a user first connect in, details about the user need to be stored in KV manner, and the second time the user connect in, his details should be able to read from the KV data structure.

I cannot use the user object as key, for it will be destructed when disconnect, and reconstructed in the second connection. The two objects are not the same reference. Integer key doesn’t fit for my requirement either for the same reason.

In other words, I need to use value as key, not reference.

Keys could be considered are: UUID(long), id(int) and so on. They are all primitive type.

Answer 1

I fail to see why you can’t simply wrap your primitive type in it’s corresponding non-primitive class and use that as your key in a regular java map.

Map<Integer, Object> map = new HashMap<Integer, Object>();
Integer key = Integer.valueOf(5);
Object test = new Object();
map.put(key, test);
Object test2 = map.get(Integer.valueOf(5));

test.equals(test2); // will be true