如何从HashMap中计算相同的值？

Question

How to get count the same values from HashMAP?

HashMap<HashMap<String, Float>, String> HM=new HashMap<HashMap<String,Float>, String>(); 

HashMap<String, Float> h;

h=new HashMap<String, Float>();                          
h.put("X", 48.0f);
h.put("Y", 80.0f);    
HM.put(typeValuesHM, "Red");

h=new HashMap<String, Float>();
h.put("X", 192.0f);
h.put("Y", 80.0f);
HM.put(typeValuesHM, "Red");

h=new HashMap<String, Float>();
h.put("X", 192.0f);
h.put("Y", 320.0f);
HM.put(typeValuesHM, "Blue");

h=new HashMap<String, Float>();
h.put("X", 336.0f);
h.put("Y", 560.0f);
HM.put(typeValuesHM, "Blue");

The values of my HashMap HM are as follows:

{ {x=48,y=80}=Red,{x=192,y=80}=Red,{x=192,y=320}=Blue,{x=336,y=560}=Blue }

Here,

I want to count the similar values in the HashMap HM.

ie) if i give value equals to "Red" means i want to get count=2. if i give value equals to "Blue" means i want to get count=2.

How to get count the same values from HashMAP HM?

Answer 1

int count = Collections.frequency(new ArrayList<String>(HM.values()), "Red");

Answer 2

Loop through the entry set and drop all values to a second map, the first maps value as a key, the value will be the count:

Map<String, Integer> result = new TreeMap<String, Integer>();
for (Map.Entry<Map<String, Float>> entry:HM.entrySet()) {
   String value = entry.getValue();
   Integer count = result.get(value);
   if (count == null)
      result.put(value, new Integer(1));
   else
      result.put(value, new Integer(count+1));
}

The result map for your example should be like this:

{"Red"=2, "Blue"=2}  // values are stored as Integer objects

Answer 3

The only way you can do it is to iterate through all the elements and count the occurrences:

for(String value: hm.values()) {
  if (value.equals(valueToCompare)) {
    count++;
  }
}

Answer 4

int countValue(String toMatch) {
  int count = 0;
  for (String v : HM.values()) {
    if (toMatch.equals(value)) {
      count++;
    }
  }
  return count;
}

Also, it is probably overkill to use a HashMap as the key if you are just storing two values. The built in Point uses int , but it would not be hard to re-implement with float .

Answer 5

    Iterator<String> iter = HM.values().iterator();
    while(iter.hasNext()) {
        String color = iter.next();

        if(color.equals("Red")) {

        } else if(color.equals("Green")) {

        }  else if(color.equals("Blue")) {

        }
    }