[Java] Be careful of the key type of Map

import java.util.*;

public class MapTest {
    public static void main(String[] argv) {
        Map<Short, Object> a = new HashMap<>();
        a.put(new Short("1"), new Object());
        System.out.println(a);  // {1=java.lang.Object@7852e922}
        System.out.println(a.get(1));   // null !!
        System.out.println(a.get(new Short("1")));  // java.lang.Object@7852e922
    }
}

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