How to number of occurrence of a word in a ArrayList?

Question

I have written the following code and got the output. import java.util.ArrayList;

public class DuplicatesinArrayList {

    public static void main(String[] args) {

        ArrayList <String> al = new ArrayList<>();
        al.add("Soumen");
        al.add("Rahul");
        al.add("Soumen");
        al.add("Ram");
        al.add("Rahul");
        al.add("Rahul");
        al.add("Rahul");
        al.add("Ram");
        al.add("Ram");
        al.add("Ram");
        al.add("Ram");

        for (int i = 0; i < al.size(); i++) {  
            int ctr = 0;
            for (int j = 0; j < al.size(); j++) {
                if(al.get(i).equals(al.get(j)))
                    ctr++;
            }
            System.out.println(al.get(i)+" present " + ctr + " times"); 
        }
    }
}

The result is as follows:

Soumen present 2 times
Rahul present 4 times
Soumen present 2 times
Ram present 5 times
Rahul present 4 times
Rahul present 4 times
Rahul present 4 times
Ram present 5 times
Ram present 5 times
Ram present 5 times
Ram present 5 times

I want for each word there should be one result. Can anyone help?

Hi RC , can u please give me the previously asked question so that I can find the answer. — Soumen Chakraborty, Aug 20 '16 at 19:29
I dont want to use Map .Without using Map how can I reach the expected result — Soumen Chakraborty, Aug 20 '16 at 19:30
??? see the [duplicate](http://stackoverflow.com/questions/505928/how-to-count-the-number-of-occurrences-of-an-element-in-a-list) or the answer here, there are some "no map" options — , Aug 20 '16 at 19:49

msumera · Answer 1 · 2016-08-20T18:57:41.607

2

You can use a map for that

Map<String, Integer> map = new HashMap<>();
for (String s : al) {
    if (map.containsKey(s)) map.put(s, map.get(s) + 1);
    else map.put(s, 1);
}

for (Map.Entry<String, Integer> entry : map.entrySet()) {
    System.out.println(entry.getKey()+" present " + entry.getValue() + " times");
}

Alternatively you can use java8 streams:

al.stream().collect(groupingBy(o -> o, counting())).forEach((name, count) -> System.out.println(name + " present " + count + " times"));

edited Aug 20 '16 at 18:57

answered Aug 20 '16 at 18:45

msumera

160
1
9

do u have any solution without using map? – Soumen Chakraborty Aug 20 '16 at 19:31

How to number of occurrence of a word in a ArrayList?

1 Answers1