对map中的value进行排序

桃扇骨 2022-06-13 14:21 306阅读 0赞

//对map中的value进行排序
    public class SortMapValue {
    	public static void main(String[] args) {
    		Map<String,Integer> map=new LinkedHashMap<String,Integer>();
    		map.put("aaa", 45);
    		map.put("e", 2);
    		map.put("ww", 556);
    		map.put("rr", 34);
    		map.put("cs", 54);
    		map.put("bs", 23);
    		map.put("g", 66);
    		Map<String,Student> map1=new HashMap<String,Student>();
    		map1.put("a", new Student("hj","cannan",23,891));
    		map1.put("t", new Student("tt","cannan",45,591));
    		map1.put("w", new Student("wj","cannan",21,291));
    		map1.put("g", new Student("gj","cannan",90,991));
    		map1.put("n", new Student("nj","cannan",7,191));
    		map1=sortMapValue(map1,"name","age");
    		for(Map.Entry<String, Student> entry:map1.entrySet()){
    			System.out.println(entry.getKey()+"#"+entry.getValue());
    		}
    		
    	}
    	/**
    	 * clazz表示要比较的类型，比如String,Integer基本类型,或者对象Student
    	 * fields:如果是对象的话,表示要比较该对象的哪个字段,多个要比较多个属性的话写上多个，前后的顺序是比较的优先级
    	 * 如果是基本类型的话fields可以不写
    	 * 如果是对象比较的话需要一个默认的构造方法
    	 * 传入的map必须为linkedhashmap，或者的话传入的即使排序好也会乱掉
    	 */
    	public static<K,V> Map<K,V> sortMapValue(Map<K,V> map,final String...fields){
    		Map<K,V> tempmap=new LinkedHashMap<K,V>();
    		Set<Entry<K,V>> set=new TreeSet<Entry<K,V>>(new Comparator<Entry<K,V>>() {
    			@Override
    			public int compare(Entry<K, V> o1, Entry<K, V> o2) {
    				int valflag=0;
    				final String ClassName=o1.getValue().getClass().getSimpleName();//得到V的类型
    				int keyflag=o1.getKey().toString().compareTo(o2.getKey().toString());
    				//比较基本类型和String类型
    				if(ClassName.equals("String")||ClassName.equals("Byte")||ClassName.equals("Character")||ClassName.equals("Short")||
    						ClassName.equals("Integer")||ClassName.equals("Long")||ClassName.equals("Float")||ClassName.equals("Double")){
    					valflag=vCompare(o1.getValue(), ClassName, o2.getValue(), ClassName);
    					if(valflag!=0){
    						return valflag;
    					}else{
    						return keyflag;
    					}
    				}else{//比较对象
    					if(fields!=null&&fields.length<=0){
    						return 0;
    					}
    					Class clazz1=o1.getValue().getClass();
    					Class clazz2=o2.getValue().getClass();
    					for(String field:fields){
    						try {
    							Field f1=clazz1.getDeclaredField(field);
    							Field f2=clazz2.getDeclaredField(field);
    							f1.setAccessible(true);
    							f2.setAccessible(true);
    							valflag=vCompare(f1.get(o1.getValue()), f1.getType().getSimpleName(), 
    									f2.get(o2.getValue()), f2.getType().getSimpleName());
    							if(valflag!=0){
    								return valflag;
    							}else{
    								return keyflag;//先假设只有一个比较参数
    							}
    						} catch (SecurityException e) {
    							e.printStackTrace();
    						} catch (NoSuchFieldException e) {
    							e.printStackTrace();
    						}catch (IllegalArgumentException e) {
    							e.printStackTrace();
    						} catch (IllegalAccessException e) {
    							e.printStackTrace();
    						}
    					}
    				}
    				return valflag;
    			}
    		});
    		for(Map.Entry<K, V> entry:map.entrySet()){
    			set.add(entry);
    		}
    		map.clear();
    		for(Entry<K,V> entry:set){
    //			System.out.println("#"+entry.getKey()+":"+entry.getValue());
    			tempmap.put(entry.getKey(), entry.getValue());
    			map.put(entry.getKey(), entry.getValue());//如果是LinkedHashmap的话就不用在调用的时候赋值了，否则需要重新赋值
    		}
    		return tempmap;
    	}
    /**'
     * 
     * @param <V>值的类型
     * @param v1 值1
     * @param type1 值的
     * @param v2
     * @param type2
     * @return
     */
    public static<V> int vCompare(V v1,String type1,V v2,String type2){
    	int valflag=0;
    	if(type1.equalsIgnoreCase("String")){
    		return v1.toString().compareTo(v2.toString());
    	}else if(type1.equalsIgnoreCase("Byte")||type1.equalsIgnoreCase("Character")||type1.equalsIgnoreCase("Short")||type1.equalsIgnoreCase("Integer")
    			||type1.equalsIgnoreCase("Long")||type1.equalsIgnoreCase("Float")||type1.equalsIgnoreCase("Double")||type1.equalsIgnoreCase("int")
    			||type1.equalsIgnoreCase("char")){
    		valflag=(int)(Double.parseDouble(v1.toString())-Double.parseDouble(v2.toString()));
    //		System.out.println(v1.toString()+":"+v2.toString());
    //		System.out.println(valflag+":"+(Double.parseDouble(v1.toString())+":"+Double.parseDouble(v2.toString())));
    		return valflag;
    	}
    	return 0;
    }
    }