Java count all the values of an array and store it in an array

Question

I want to count values of an array and keep it into an array.In php we do so using array_count_values.

    $a=array("A","Cat","Dog","A","Dog");
    print_r(array_count_values($a));

Output :

    Array ( [A] => 2 [Cat] => 1 [Dog] => 2 )

I want to do so in java.

Map<String, String[]> map = request.getParameterMap();
String[] wfBlockIds     = map.get("wf_block_id[]");
        Arrays.stream(wfBlockIds)
          .collect(Collectors.groupingBy(s -> s))
          .forEach((k, v) -> System.out.println(k+" => "+v.size() + " --" + v));

Output of the Java Code is :

1469441140125 => 3 --[1469441140125, 1469441140125, 1469441140125]
1469441126299 => 2 --[1469441126299, 1469441126299]

How can I will get equivalent result as array_count_values() which will be in an array.

output will be an array that will contain element of wfBlockIds array.Array ( [A] => 2 [Cat] => 1 [Dog] => 2 ) — M.Topa
– M.Topa, Commented Jul 25, 2016 at 10:35
Please update your question instead of putting infos in comments. — GhostCat
– GhostCat, Commented Jul 25, 2016 at 10:36
Arrays in Java can only have int indices, so what you are requesting is not possible, perhaps a Map<String,Integer> will work for you. — Eran
– Eran, Commented Jul 25, 2016 at 10:37

xenteros · Accepted Answer · 2016-07-25 10:36:35Z

2

Try the following code:

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

answered Jul 25, 2016 at 10:36

xenteros

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Comments

Spotted · Accepted Answer · 2016-07-25 11:09:05Z

1

Altough Java arrays only have int indices, you can achieve the same functionnality as in PHP with a Map.

The following code produces something similar to array_count_values

Map<String, Long> result = Stream.of("A", "Cat", "Dog", "A", "Dog")
                                 .collect(groupingBy(Function.identity(), counting()));
System.out.println(result); //prints {A=2, Cat=1, Dog=2}

answered Jul 25, 2016 at 11:09

Spotted

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Comments

Elgayed · Accepted Answer · 2016-07-25 10:52:29Z

0

Your code is fine, but the String array that you are getting from request params contains 3 * "1469441126299" and 2 * "1469441140125"; Print out your request.getParameterMap() and you will see that

answered Jul 25, 2016 at 10:52

Elgayed

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1 Comment

Elgayed Over a year ago

try to use request.getParameter("wf_block_id[]") without calling the parameterMap

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