Is there a way to get the value of a HashMap randomly in Java? Of Course, below is a simple Java Code which represents the same.
Generate private and public key pair. Creates an empty HashMap which will use the given hash builder to hash keys. The created map has the default initial capacity. Warning: hashbuilder is normally randomly generated, and is designed to allow HashMaps to be resistant to attacks that cause many collisions and very poor performance. Dec 20, 2013 Choose random key from Hashmap. Discussion in 'Plugin Development' started by bluegru, Dec 20, 2013. Thread Status: Not open for further replies. Offline bluegru. Is there a way to chose a random key from a hashmap? I have a hashmap with player as key and want to get a random. Selecting the random HashMap is trivial, but how should I select a random key from within this HashMap? Speed is important (as I need to do this 10000 times and the hashmaps are large), so just selecting a random number k in 0,9999 and then doing.next on the iterator k times, is really not an option.
Also, at the end of program there is a bonus code to Shuffle complete HashMap. Reshuffling a large collection is always going to be expensive. You are going to need at least one reference per entry. e.g. for 1 million entries you will need approx 4 MB.
Hashmap With Random Generated Keys In Math
Download game bomb squad mod apk revdl. Diablo 2 cd key creator. Note; the shuffle operation is
O(N)
CrunchifyGetRandomKeyValueFromHashMap.java
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 | importjava.util.Collections; importjava.util.List; importjava.util.Random; /** * publicstaticvoidmain(String[]args){ // Create a hashtable and put some key-value pair. HashMap<String,String>companies=newHashMap<String,String>(); companies.put('Paypal','North San Jose'); companies.put('Yahoo','Santa Clara'); Object[]crunchifyKeys=companies.keySet().toArray(); Objectkey=crunchifyKeys[newRandom().nextInt(crunchifyKeys.length)]; System.out.println('************ Random Value ************ n'+key+' :: '+companies.get(key)); List<Map.Entry<String,String>>list=newArrayList<Map.Entry<String,String>>(companies.entrySet()); // Bonus Crunchify Tips: How to Shuffle a List?? System.out.println('n************ Now Let's start shuffling list ************'); for(Map.Entry<String,String>entry:list){ System.out.println(entry.getKey()+' :: '+entry.getValue()); } |
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Output
2 4 6 8 | Twitter::San Francisco ************Now Let'sstart shuffling list ************ eBay::South San Jose Twitter::San Francisco |
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Java Hashmap Get Keys
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