java hashmap with multiple same keys

Does "discord" mean disagreement as the name of an application for online conversation? To learn more, see our tips on writing great answers. In parameters - can K be a regular expression, for example? There needs to be only 1 single map and just a simple wrapper method that would put your keys and value into that map. Do large language models know what they are talking about? Sometimes two words (or variations of a word) are mapped to the same response. a) Use 2 different maps. How to resolve the ambiguity in the Boy or Girl paradox? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Some people suggest me to use a tuple, a pair, or similar as a key for To learn more, see our tips on writing great answers. I prefer the following to store any number of variables without having to create a separate class. If there is, please, explain it. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing, @rowana you can create a new class holding two. Java HashMap, One key multiple Values, One map, Associating two values to a single key in a java HashMap, Java - multiple hashmaps pointing to the same key. Is the difference between additive groups and multiplicative groups just a matter of notation? Creating HashMap by associating multiple values with same Key - thisPointer Asking for help, clarification, or responding to other answers. @Jezor but this time using map structure wont be meaningful. . Or are you just indicating that the user is to specify 1, 2 or up to N when they create the class. Should I sell stocks that are performing well or poorly first? How to add Unique Values to a Hashmap at an Existing Key, HashMap with multiple values under the same key, one key multiple values in HashMap using object, Hashmaps having multiple keys with multiple values, Java HashMap, One key multiple Values, One map. Why schnorr signatures uses H(R||m) instead of H(m)? You cannot find your own code? Can I have a hash map in Java that looks like this? How to create a HashMap with two keys (Key-Pair, Value)? Using primes is another option as per "Effective Java", e.g. Updating is a problem in my response as well. 0. It's just the question that is wrong ;). rev2023.7.3.43523. If each key is in each file and all have values, you could store values from first file at 0th index, from the second at 1st index etc. Below is the syntax for inserting the values into HashMap. Why did CJ Roberts apply the Fourteenth Amendment to Harvard, a private school? Are the ellipsis arguments actual ellipses? Thanks for contributing an answer to Stack Overflow! Peace out. Am gonna count this as a correct answer as it does exactly what i asked, but following the conversation above, unfortunately, it will not solve my problem :) I'll have to come up with another tactic! Is the executive branch obligated to enforce the Supreme Court's decision on affirmative action? Is there a finite abelian group which is not isomorphic to either the additive or multiplicative group of a field? Not the answer you're looking for? A Guide to ConcurrentMap | Baeldung How do laws against computer intrusion handle the modern situation of devices routinely being under the de facto control of non-owners? How do laws against computer intrusion handle the modern situation of devices routinely being under the de facto control of non-owners? Guava has various Multimap implementations, usually created via the Multimaps class. 164.56K Views Join the DZone community and get the full member experience. gdalwarp sum resampling algorithm double counting at some specific resolutions, Formulating P vs NP without Turing machines. Formulating P vs NP without Turing machines. Create a simple class holding two String objects: And then use it's objects as keys in your map: Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. For example, we want to keep the track of strings and their occurrences in the text. Thinking about a Map with 2 keys immediately compelled me to use a user-defined key, and that would probably be a Class. Comic about an AI that equips its robot soldiers with spears and swords. What syntax could be used to implement both an exponentiation operator and XOR? A hashmap is a structure that is optimized for associative access of the values using the keys, but is in no way better in doing the reverse then an array for instance. I would like to be able to sum the pet price for each shop. So in your case, if you have. Hashtables - Same key many values? How can I create an executable/runnable JAR with dependencies using Maven? How link multiple keys to the same value in the HashMap 4 parallel LED's connected on a breadboard, Lateral loading strength of a bicycle wheel. Thanks for contributing an answer to Stack Overflow! Not the answer you're looking for? How to print keys with duplicate values in a hashmap? Java - multiple hashmaps pointing to the same key - Stack Overflow How to take large amounts of money away from the party without causing player resentment? https://commons.apache.org/proper/commons-collections/apidocs/. Not the answer you're looking for? Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing. 2. It does still have close to the same memory usage as the two map approach in another answer, but might be more straight-forward. Does "discord" mean disagreement as the name of an application for online conversation? http://insidecoffe.blogspot.de/2013/04/indexable-hashmap-implementation.html. In this way a single map can used for both keys. In my case it was my Event Object). Is the difference between additive groups and multiplicative groups just a matter of notation? Eg. So I search for a object in my searchfield and I want to store all those objects that has that name into an ArrayList so I can change info in just them. Now i want to know all keys whose value is x (ans: [1,3] ). Yes and no. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. The only thing I can think of is: How can I add such "multiple" keys? HashMap with multiple values under the same key, Java HashMap, One key multiple Values, One map, Comic about an AI that equips its robot soldiers with spears and swords. I want to store each file in a separate hashmap, ie map, so if there are five files, then there will be five hashmaps. How do you know which K2 to use? The thing is that I need to use a HashMap instead of a ArrayList on this part of the project because HashMap is alot faster for searching. If not, is there any other way to implement the storage of multiple values e.g. Stone-Weierstrass theorem for non-polynomials. If keys are unique then there is no need for 2 maps, map of maps, mapOfWhateverThereIs. Not the answer you're looking for? You'll have to write or find Pair<>; it's pretty easy but not part of the standard Collections. the program only gets the last value for each shop since there are multiple shops with the same name but different pet price. 586), Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood, Testing native, sponsored banner ads on Stack Overflow (starting July 6), Temporary policy: Generative AI (e.g., ChatGPT) is banned, HashMap with multiple values under the same key, Hashmaps having multiple keys with multiple values, Java HashMap, One key multiple Values, One map, Java: Multiple keys, one value HashMap, pointing to the exact same value. HashMap in Java - GeeksforGeeks Asking for help, clarification, or responding to other answers. Why would the Bank not withdraw all of the money for the check amount I wrote? 586), Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood, Testing native, sponsored banner ads on Stack Overflow (starting July 6), Temporary policy: Generative AI (e.g., ChatGPT) is banned. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. In the final act, how to drop clues without causing players to feel "cheated" they didn't find them sooner? By the way, in a lot of common cases the space of key1 and the space of key2 do not intersect. @gaurav: It's been so long since I've been in the Java world that I wouldn't like to say. Developers use AI tools, they just dont trust them (Ep. Sounds like you might be a little confused about the difference between keys and hashed keys. The other remaining files would be the extrinsic set of values, but I don't know how to relate the values back to the base (intrinsic) keys without duplicating the keys? Stone-Weierstrass theorem for non-polynomials. Making statements based on opinion; back them up with references or personal experience. In my case, it was 2, so I opted for this over a List. He can just use a list. Can we have multiple values for same key in HashMap? Is the difference between additive groups and multiplicative groups just a matter of notation? Even though Hashtable is thread safe, it is not very efficient. If you want values of diferent classes instead, you can do the following: Can be done using an identityHashMap, subjected to the condition that the keys comparison will be done by == operator and not equals(). Note that in map, get() and containsKey() etc all take Object arguments. This would be more efficient. The OP doesn't want to map using keyA and keyB, rather keyA or keyB, this is a really elegant (partial) solution, but the keys could be from different types (as the question states "I need a data structure which behaves like a Map, but uses multiple. Overview In this tutorial, we're going to explore different ways to compare two HashMaps in Java. How can I avoid Java code in JSP files, using JSP 2? Assuming constant operation cost, are we guaranteed that computational complexity calculated from high level code is "correct"? Hey, thanks for the feedback Laf, the only problem I get with this is the row, @FilipBlom YEah I made a typo. And then use it's objects as keys in your map: HashMap<MyKey, Integer> hmap = new HashMap<>() . The asker does not need a compound key, but two distinct single keys that point to the same object but are managed as one entry so to say. When did a PM last miss two, consecutive PMQs? Thanks for contributing an answer to Stack Overflow! gdalwarp sum resampling algorithm double counting at some specific resolutions. Is there any political terminology for the leaders who behave like the agents of a bigger power? What happens when we try to add a duplicate key into a HashMap object This is Google-Guava library for utility functionalities. Like, Map? you may even simply use an. A dirty and a simple solution, if you use the maps just for sorting lets say, is to add a very small value to a key until the value does not exist, but do not add the minimum (for example Double.MIN_VALUE) because it will cause a bug. If you know any reason why it could not be used as a solution for such issues - please, let me know! What are the implications of constexpr floating-point math? How does this work , when you want to lookup by just key1 ? Perhaps you'd need type registration so you don't get class casting problems (if they're special + implemented naively. 5 HashMaps * 1000 keys is a very small number, and you shouldn't have memory issues. Book about a boy on a colony planet who flees the male-only village he was raised in and meets a girl who arrived in a scout ship. What's the best Java data structure for multiple values with same key? Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing. Connect and share knowledge within a single location that is structured and easy to search. It would seem to me that the methods you want in your question are supported directly by Map. Drawbacks: Not generic. Deal with this by mapping synonyms or related expressions to the same string so that you do not need multiple entries in the response map for the same response. java - HashMap with multiple values under the same key - Stack Overflow I would also not like to use more than 1 class for this job. By clicking Post Your Answer, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct. I need to avoid adding the same value twice. add the String to the internal pool if it didn't exist already; return the equivalent String from the pool if it already existed. I used such implementation for multiple key objects. Asking for help, clarification, or responding to other answers. Qa/qc Plan For Construction Project Sample, How Old Are Cavendish And Dakota, Central Florida Christian Academy Football, I Am Impressed By Your Personality, Gross High School Summer Camps, Articles J