TreeMap比较器实现

一、将TreeMap中指定元素排在集合前面

1. 比较器实现

/**
 * TreeMap比较器
 *
 */
public class MyComparator implements Comparator<String>{
 
 private Map<String,Integer> bankCodeMap = new HashMap<String,Integer>();
 private int tempWeight = 0;
 
    public MyComparator(){
       bankCodeMap.put("ICBC", 1);
       bankCodeMap.put("CCB", 2);
       bankCodeMap.put("ABC", 3);
    }

 @Override
 public int compare(String o1, String o2) {
  int weight1 = getWeight(o1);
  int weight2 = getWeight(o2);

  return weight1-weight2;
 }

 /**
  * 获取权重
  * @param key
  * @return
  */
 private int getWeight(String key){
  Integer value = bankCodeMap.get(key);
  if(value == null){
   if(tempWeight == 0){
    tempWeight = Collections.max(bankCodeMap.values()) + 1;
   }else{
    tempWeight = tempWeight + 1;
   }
   
   value = tempWeight;
   bankCodeMap.put(key, value);
  }
  return value;
 }

}

2. 测试代码

TreeMap<String,String> map = new TreeMap<String,String>(new MyComparator());
  map.put("UOP", "STR1");
  map.put("HP", "STR2");
  map.put("ICBC", "STR3");
  map.put("ABC", "STR4");
  map.put("CCB", "STR5");
  map.put("GDB", "STR6");
  
  System.out.println(map);