链接哈希图排序

Question

我正在尝试根据其值对LinkedHashMap进行排序。我不明白的是结果。它似乎只需要两个键进行排序。关于我错过了什么的任何指示？

public class test {
    public static void main(String[] args) {
        // TODO Auto-generated method stub

        LinkedHashMap<Integer, Integer> sorting = new LinkedHashMap<Integer, Integer>();
        sorting.put(1, 100);
        sorting.put(10, 100);
        sorting.put(20, 200);
        sorting.put(30, 100);
        sorting.put(40, 100);
        sorting.put(50, 200);
        for (Entry<Integer, Integer> entry : sorting.entrySet()) {
             Integer key = entry.getKey();
             Integer value = entry.getValue();
             System.out.println("LINKED UNSORTED === key: "+ key + 't' + "Value: " + value);
              // do stuff
            }

        Comparator<Integer> comparator = new ValueCom(sorting);
        TreeMap<Integer, Integer> sortedMap =new TreeMap<Integer, Integer>(comparator);
        sortedMap.putAll(sorting);      

        for (Entry<Integer, Integer> entry : sortedMap.entrySet()) {
             Integer key = entry.getKey();
             Integer value = entry.getValue();
             System.out.println("SORTED   === key: "+ key + 't' + "Value: " + value);
              // do stuff
            }
    }
}

class ValueCom implements Comparator<Integer> {
    LinkedHashMap<Integer, Integer> map = new LinkedHashMap<Integer, Integer>();
public ValueCom(HashMap<Integer, Integer> map) {
        this.map.putAll(map);
    }
public int compare(Integer keyA, Integer keyB){
    return map.get(keyB).compareTo(map.get(keyA));
}
} 

电流输出如上所述

LINKED UNSORTED === key: 1  Value: 100
LINKED UNSORTED === key: 10 Value: 100
LINKED UNSORTED === key: 20 Value: 200
LINKED UNSORTED === key: 30 Value: 100
LINKED UNSORTED === key: 40 Value: 100
LINKED UNSORTED === key: 50 Value: 200
SORTED   === key: 20    Value: 200
SORTED   === key: 1 Value: 100

Answer 1

在TreeMap中，键的唯一性由传递的Comparator决定。由于您的Comparator比较原始Map的值，因此TreeMap认为具有相同值的所有条目都具有相同的键，因此每个唯一值只会向TreeMap添加一个条目。

如果要按值对Map进行排序，则可以对排序Map使用LinkedHashMap，并确保按所需顺序将条目放入Map中。

Answer 2

问题是您是根据值进行排序的，如果两个值相等，则树状图将只为该键进行单个输入，您可以通过查看下面的代码更好地理解。下面的代码将解决问题，如果有任何失败，请告诉我：

修改类ValueCom compare()方法，如下所示：

    public int compare(Integer i1, Integer i2) {
        if(map.get(i1).equals(map.get(i2))){
            return 1; //To make sure, If values are equal then still there should be entry in TreeMap
        }
        return map.get(i1).compareTo(map.get(i2));
    }

现在，还处理了相等值的情况。 :)

Answer 3

下面的代码给你你想要的

public class test {
public static void main(String[] args) {
    // TODO Auto-generated method stub

    LinkedHashMap<Integer, Integer> sorting = new LinkedHashMap<Integer, Integer>();
    sorting.put(10, 100);
    sorting.put(1, 100);
    sorting.put(20, 200);
    sorting.put(40, 100);
    sorting.put(30, 100);
    sorting.put(50, 200);
    for (Entry<Integer, Integer> entry : sorting.entrySet()) {
         Integer key = entry.getKey();
         Integer value = entry.getValue();
         System.out.println("LINKED UNSORTED === key: "+ key + 't' + "Value: " + value);
          // do stuff
        }

    Comparator<Integer> comparator = new ValueCom();
    TreeMap<Integer, Integer> sortedMap =new TreeMap<Integer, Integer>(comparator);
    sortedMap.putAll(sorting);      

    for (Entry<Integer, Integer> entry : sortedMap.entrySet()) {
         Integer key = entry.getKey();
         Integer value = entry.getValue();
         System.out.println("SORTED   === key: "+ key + 't' + "Value: " + value);
          // do stuff
        }
}
}

class ValueCom implements Comparator<Integer> {
public int compare(Integer keyA, Integer keyB){
return keyA.compareTo(keyB);
}
}