"Java JavaScript Julia".toLowerCase().chars()
                       .filter(ch -> ch == 'j' || ch == 'a')
                       .boxed()
                       .collect(Collectors.groupingBy(Function.identity(), LinkedHashMap::new, Collectors.toList()))
                       .entrySet().stream()
                       .map(jaEntry -> jaEntry.getValue().size() + Character.toString(jaEntry.getKey()))
                       .collect(Collectors.joining())

"Java JavaScript Julia".toLowerCase().split("")
                       .reduce((a, b) => a[b] !== undefined ? (a[b] += 1, a) : a, 
                        {j: 0, a: 0, _: function() {return `${this.j}j${this.a}a`}})
                       ._(); 

"Java JavaScript Julia" |> lowercase |> collect |> 
                        chs -> reduce(function(dict, ch) haskey(dict, ch) ? (dict[ch] += 1; dict) : dict end, 
                                      chs, init = Dict('j' => 0, 'a' => 0)) |> 
                        collect |> 
                        jaPairs -> map(jaPair -> string(jaPair[2], jaPair[1]), jaPairs) |> 
                        join