Map的key、value值的数据类型不能为基本类型的原因

interface Map<K,V>
Map源码

		 /**
         * Returns the hash code value for this map entry.  The hash code
         * of a map entry <tt>e</tt> is defined to be: <pre>
         *     (e.getKey()==null   ? 0 : e.getKey().hashCode()) ^
         *     (e.getValue()==null ? 0 : e.getValue().hashCode())
         * </pre>
         * This ensures that <tt>e1.equals(e2)</tt> implies that
         * <tt>e1.hashCode()==e2.hashCode()</tt> for any two Entries
         * <tt>e1</tt> and <tt>e2</tt>, as required by the general
         * contract of <tt>Object.hashCode</tt>.
         *
         * @return the hash code value for this map entry
         * @see Object#hashCode()
         * @see Object#equals(Object)
         * @see #equals(Object)
		 */
        int hashCode();

hashCode返回 (e.getKey()==null ? 0 : e.getKey().hashCode()) ^(e.getValue()==null ? 0 : e.getValue().hashCode())

class HashMap<K,V> extends AbstractMap<K,V> implements Map<K,V>, Cloneable, Serializable
HashMap源码中：

public final int hashCode() {
	return Objects.hashCode(key) ^ Objects.hashCode(value);
}

static final int hash(Object key) {
	int h;
	return (key == null) ? 0 : (h = key.hashCode()) ^ (h >>> 16);
}

public final boolean equals(Object o) {
	if (o == this)
        return true;
    if (o instanceof Map.Entry) {
        Map.Entry<?,?> e = (Map.Entry<?,?>)o;
    if (Objects.equals(key, e.getKey()) &&
        Objects.equals(value, e.getValue()))
        return true;
    }
    return false;
}