我正在尝试使用 Comparator 接口对 TreeMap(将 Double 作为值,将 Integer 值作为键)进行排序,但它不起作用。
// Create a tree map
TreeMap tm = new TreeMap();
// Put elements to the map
tm.put(1, new Double(3434.34));
tm.put(0, new Double(123.22));
tm.put(4, new Double(1378.00));
tm.put(2, new Double(99.22));
tm.put(3, new Double(-19.08));
List<Map.Entry> valueList = new ArrayList(tm.entrySet());
// Collections.sort(valueList, new Sort());
Collections.sort(valueList, new Sort());
HashMap sortedMap = new HashMap();
// Get an iterator
Iterator<Map.Entry> i = valueList.iterator();
// Display elements
while (i.hasNext()) {
Map.Entry object = i.next();
sortedMap.put(object.getKey(), object.getValue());
}
List sortedList = new ArrayList(sortedMap.entrySet());
Iterator<Map.Entry> iterator = sortedList.iterator();
while (iterator.hasNext()) {
Map.Entry entry = iterator.next();
System.out.println("Value " + entry.getValue() + "\n");
}
以下是我的比较器类
public class Sort implements Comparator<Map.Entry> {
@Override
public int compare(Map.Entry o1, Map.Entry o2) {
// TODO Auto-generated method stub
double valueOne = (Double) o1.getValue();
double valueTwo = (Double) o2.getValue();
int returnValue =
valueOne > valueTwo ? -1 : (valueOne == valueTwo ? 0 : 1);
return (valueOne > valueTwo ? -1 : (valueOne == valueTwo ? 0 : 1));
}
}
但我得到以下输出
Value 123.22
Value 3434.34
Value 99.22
Value -19.08
Value 1378.0
Edited Part
public int compare(Map.Entry o1, Map.Entry o2) {
// TODO Auto-generated method stub
double valueOne = ((Double) o1.getValue()).doubleValue();
double valueTwo = ((Double) o2.getValue()).doubleValue();
int returnValue =
valueOne > valueTwo ? -1 : (valueOne == valueTwo ? 0 : 1);
return (valueOne > valueTwo ? -1 : (valueOne == valueTwo ? 0 : 1));
}