须要继承Map的equals函数和hashCode函数

package com.category;import java.util.HashMap;public class GenCategoryLevelData {	private static HashMap
     
       categoryLevel = new HashMap
      
       ();	/**	 * @param args	 */	public static void main(String[] args) {		// TODO Auto-generated method stub			}	/**	 * 分类	 * @author ouyangyewei	 *	 */	public static class Category {		public long categoryId;		public String categoryName;				@Override		public boolean equals(Object obj) {			Category category = (Category)obj;			return (this.categoryId==category.categoryId					&& this.categoryName.equals(category.categoryName));		}		@Override		public final int hashCode() {            int hashCode = 17;            hashCode = hashCode * 31 + 1;            hashCode = hashCode * 31 + 1;            return hashCode;        }				public Category() {			// empty		}		public Category(long categoryId, String categoryName) {			this.categoryId = categoryId;			this.categoryName = categoryName;		}		public long getCategoryId() {			return categoryId;		}		public void setCategoryId(long categoryId) {			this.categoryId = categoryId;		}		public String getCategoryName() {			return categoryName;		}		public void setCategoryName(String categoryName) {			this.categoryName = categoryName;		}	}}