The modifier readonly means that the value cannot be assigned except in the declaration or constructor. It does not mean that the assigned object becomes immutable. If you want your object to be immutable, you must use a type that is immutable. The type ReadOnlyCollection<T> that you mentioned is an example of a immutable collection. … Read more
There’s a huge difference between iterators and views. Iterators are use once only, compute on demand, while views are use multiple times, recompute each time, but only the elements needed. For instance: scala> val list = List(1,2,3).map{x => println(x); x * 2} 1 2 3 list: List[Int] = List(2, 4, 6) scala> list(2) res14: Int … Read more
if (a.Intersect(b).Any())
Creating a Map from a Set and a Function Here are two classes that should each do the job. The first just shows a map view of the set, while the second can write values back to the set through a special interface. Call Syntax: Map<K,V> immutable = new SetBackedMap<K,V>(Set<K> keys, Function<K,V> func); Map<K,V> mutable … Read more
Because Java collections can only store Object References (so you need to box primitives to store them in collections). Read this short article on Autoboxing for more info. If you want the nitty gritty details, it pretty much boils down to the following: Local Primitives are stored on the Stack. Collections store their values via … Read more
Use the constructor: HashSet<type> set2 = new HashSet<type>(set1); Personally I wish LINQ to Objects had a ToHashSet extension method as it does for List and Dictionary. It’s easy to create your own of course: public static HashSet<T> ToHashSet<T>(this IEnumerable<T> source) { if (source == null) { throw new ArgumentNullException(“source”); } return new HashSet<T>(source); } (With … Read more
This is one solution. If you want to make it more generic, you can use the StringUtils library. String value = “{first_name = naresh,last_name = kumar,gender = male}”; value = value.substring(1, value.length()-1); //remove curly brackets String[] keyValuePairs = value.split(“,”); //split the string to creat key-value pairs Map<String,String> map = new HashMap<>(); for(String pair : keyValuePairs) … Read more
You can update it with a dictionary, since add another string is same as update the key with count +1: from collections import Counter c = Counter([‘black’,’blue’]) c.update({“red”: 1}) c # Counter({‘black’: 1, ‘blue’: 1, ‘red’: 1}) If the key already exists, the count will increase by one: c.update({“red”: 1}) c # Counter({‘black’: 1, ‘blue’: … Read more
I use the random.next(0, array.length), but this give random number of the length and i need the random array numbers. Use the return value from random.next(0, array.length) as index to get value from the array Random random = new Random(); int start2 = random.Next(0, caminohormiga.Length); Console.Write(caminohormiga[start2]);