java – CompareTo可能返回0,替代TreeSet / TreeMap

你说：

I have a set of displayable objects. I want to sort them by Y coordinate,so that they are rendered in the correct order. Of course,two objects may well have the same Y coordinate.

那么,如果两个元素具有相同的Y坐标,那么你先放入什么？其他标准是什么？

它可能是创建时间,也可能是x坐标,您只需要定义它：

Map<String,Thing> map = new TreeMap<String,Thing>(new Comparator<Thing>(){
     public int compare( Thing one,Thing two ) {
         int result = one.y - two.y;
         if( result == 0 ) { // same y coordinate use another criteria
             result = one.x - two.x;
             if( result == 0 ) { //still the same? Try another criteria ( maybe creation time
                 return one.creationTime - two.creationTime
             }
          }
          return result;
     }
});

你必须定义什么时候一件东西比其他东西更高/更低/相等/更高.如果其中一个属性与其他属性相同,则可能不应移动它们.如果有其他属性要比较使用它.