Is this the easiest way to find the maximum count value of a list of integers? I have a list of integers and need to find the maximum count of how often they each occur – so loop through the list, adding to a hashmap the value and the count, then if the value already exists just increment the count.
public class TestApp {
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
//Try with list of set values
List<Integer> listSet = new ArrayList<Integer>();
listSet.add(1);
listSet.add(1);
listSet.add(5);
listSet.add(3);
listSet.add(5);
listSet.add(1);
System.out.println("Maximum count value of int list with set values: ");
System.out.println( getMaxCountValue(listSet) );
//Test with list of random values
List<Integer> listRandom = new ArrayList<Integer>();
Random rdmGen = new Random();
for (int i = 1; i <= 1000; i++) {
int rdmInt = rdmGen.nextInt(25);
System.out.println(rdmInt);
listRandom.add(rdmInt);
}
System.out.println("Maximum count value of int list with random values: ");
System.out.println( getMaxCountValue(listRandom) );
}
/**
* Desc Method to return maximum value of occurrences of integers in list
* @param List<Integer>
* @returns Integer - maximum count value
*/
private static Integer getMaxCountValue(List<Integer> myList){
HashMap<Integer, Integer> frequencymap = new HashMap<Integer, Integer>();
Integer maximum = 0;
//Loop through list
for(Integer integerObj : myList) {
//If the hashmap contains the value then increase count
if(frequencymap.containsKey(integerObj.intValue())) {
frequencymap.put(integerObj.intValue(), frequencymap.get(integerObj.intValue())+1);
}else{
//add value with count of 1
frequencymap.put(integerObj.intValue(), 1);
}
}
//Loop through hashmap to find the maximum count
for (int value : frequencymap.values()) {
if(value > maximum){
maximum = value;
}
}
return maximum;
}
}
Of course if you’re interested in the value to count relationship then could return the hashmap.
