java list remove duplicates by multiple propertyjava list remove duplicates by multiple property

Java - merge two lists removing duplicates based on the value of a property. My manager warned me about absences on short notice. I just realized you mention an address will always be unique inside an address list. Java 8 Stream remove "almost" duplicates from list? Not the answer you're looking for? What are the advantages and disadvantages of the callee versus caller clearing the stack after a call? Would a room-sized coil used for inductive coupling and wireless energy transfer be feasible? (Student supplier is a simple supplier function of list of students), Note: Only duplicate records with studentName matching and percentage 100 must be removed,(Record Ronon has percentage 100 but there is no duplicate with the same studentname so that must not be removed). (For a list with N Remove outermost curly brackets for table of variable dimension. (This is essentially the same as my answer to this question: Java Lambda Stream Distinct() on arbitrary key?). Commercial operation certificate requirement outside air transportation, Non-definability of graph 3-colorability in first-order logic. Many times, we need to avoid duplication in the List. Why do keywords have to be reserved words? Asking for help, clarification, or responding to other answers. What languages give you access to the AST to modify during compilation? I need to retrieve all the obj1s where city and country must not be duplicate. You cannot use sets to remove duplicates without proper equals and hashcode, which in your case should be build by name and Connect and share knowledge within a single location that is structured and easy to search. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. This will assure you don't have any duplicate objects in the Set. Spying on a smartphone remotely by the authorities: feasibility and operation. What are the advantages and disadvantages of the callee versus caller clearing the stack after a call? This comparator functions are generally easier to use, and perhaps less error prone. why isn't the aleph fixed point the largest cardinal number? See my edited answer. This depends on what you want to do with the stream of distinct elements which you didnt tell us in your question. Remove duplicates from list based on some property, Why on earth are people paying for digital real estate? List listWithDistinctPersons = persons.stream() //operators to remove duplicates based on person name .collect(Collectors.groupingBy(p -> desire output After removing the duplicates: What i have right now is only removing duplicates based on the name and not considering the percentage(100)and also not preserving the order..any help is greatly appreciated. How to remove duplicates from an ArrayList in Java Were Patton's and/or other generals' vehicles prominently flagged with stars (and if so, why)? for the property Name (the same for the property Id etc. Instead of, override equals() and hashCode() in your Student class and add your elements (originally in a ArrayList ) in a LinkedHashSet to keep the actual order. Remove duplicates Connect and share knowledge within a single location that is structured and easy to search. A variation of the top answer that handles null: In my case I needed to control what was the previous element. Good algorithm/technique to find overlapping values from objects' properties? Will just the increase in height of water column increase pressure or does mass play any role in it? WebThe arraylist contains duplicate elements. Stream partition answer by Tagir Valeev inspired me to use custom Collector which returns Map>. Remove duplicates from list based on Why did Indiana Jones contradict himself? :), For those who might confuse for "", replace with "it.getYourProperty()". Why do keywords have to be reserved words? Java Program to Remove duplicate elements from ArrayList I have a list of complex objects that have multiple nested objects. Science fiction short story, possibly titled "Hop for Pop," about life ending at age 30. I want to remove duplicate records from an arraylist based on multiple properties. Closed 3 years ago. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. To learn more, see our tips on writing great answers. What would stop a large spaceship from looking like a flying brick? A+B and AB are nilpotent matrices, are A and B nilpotent? If it is correct to remove any student with an attendence of 100 (by the way, that's a typo, the proper word is attendance), then all this stuff about 'duplicates' is a red herring, and all you need is: But if the idea is: Remove a record only if its attendence is 100+, and there is at least one other record in the list with the same name, it gets more complicated. Why free-market capitalism has became more associated to the right than to the left, to which it originally belonged? Thank you Eritrean..your solution has covered my scenarios..thankyou very much.i don't have enough votes to up your solution.thankyou very much, how is the output distinct based on keys? java - Finding duplicated objects by two properties - Stack Overflow rev2023.7.7.43526. Remove duplicates from list based on some property Do you need an "Any" type when implementing a statically typed programming language? Many times, we need to avoid duplication in the List. Do I remove the screw keeper on a self-grounding outlet? for the property Name (the same for the property Id etc. WebIf your Blog class has an appropriate equals() method defined on it, the simplest way is just to create a Set out of your list, which will automatically remove duplicates: List blogList = ; // your initial list Set noDups = new HashSet(blogList) You can use some helper methods (Or create a custom comparator that define something similar to): And for instance if num is a nullable property, you can use: Finally, if you want to access this comparator from 'anywhere', you can wrap the definition in a comparator, as a final field, or static for a singleton, or just as a final static field in a helper class for custom comparators. How can I learn wizard spells as a warlock without multiclassing? Thanks for contributing an answer to Stack Overflow! Why did the Apple III have more heating problems than the Altair? Another version which is simple BiFunction,List ,TreeSet> appendTree = (y,x) -> (y.addAll(x))? y:y; How to remove Duplicated elements from a List based on Two properties using Java 8 streams? How do I remove duplicates from a list, while preserving order? How to remove duplicates from an ArrayList in Java - In Java, Set object does not allow duplicate elements so you can remove duplicates from a list by creating a set object by passing required List object to its constructor.Example:import java.util.ArrayList; import java.util.LinkedHashSet; import java.util.Set; public class ArrayListSample { Thanks for the comment, I've updated my answer. In the movie Looper, why do assassins in the future use inaccurate weapons such as blunderbuss? Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing, I guess for better compatibility the argument should be, @java_newbie The Predicate instance returned by, @holandaGo It will fail if you save and reuse the Predicate instance returned by. But we need to make sure the collection implemented removeIf, for example it will throw exception if we construct the collection use Arrays.asList(..). Why add an increment/decrement operator when compound assignments exist? To learn more, see our tips on writing great answers. First implement equals and hashCode in your person class and then use. Java - merge two lists removing duplicates based on the value of a Removing Duplicates Using Plain Java A simple way is to remove the duplicates to clean up the list using List.contains () method. 2) stream.removeIf(e->!seen.add(e.getID())); is also another very good solution. What is the reasoning behind the USA criticizing countries and then paying them diplomatic visits? We can easily remove the duplicate elements from a List with the standard Java Collections Framework through a Set: public void Create a wrapper object which will have equals method based on your needs: There is unfortunately no built-in method to distinct a collection based on criteria. Another idea could be to use a wrapper that wraps an employee and have the equals and hashcode method based with its id: Then you wrap each instance, call distinct(), unwrap them and collect the result in a list. This is the complex object and elements to compare for duplicates. This is nice solution to remove duplicate items from the list. +1. This is of course less readable but sometimes it can be helpful to avoid the method. (Ep. Making statements based on opinion; back them up with references or personal experience. Edit: I have noticed the question was edited and the problem is slightly different. Thanks! Remove duplicates I wonder why this is not added in the java 8 library. Create a new list and Pass every value of the original list to the contains () method on a new list. why didn't you just add a .filter(e -> ) on your Stream? I don't want to filter out complete status. Why do keywords have to be reserved words? Java stream remove duplicate list of objects of list property rev2023.7.7.43526. Create a new list and Pass every value of the original list to the contains () method on a new list. remove duplicates 587), The Overflow #185: The hardest part of software is requirements, Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood, Temporary policy: Generative AI (e.g., ChatGPT) is banned, Testing native, sponsored banner ads on Stack Overflow (starting July 6), Remove duplicates from a list of objects based on property in Java 8, Java 8 stream - merge two collections keeping it unique by specific field, How to filter 2 huge list with millions of item in it with same id, JAVA : How to remove duplicates from list using stream, Select distinct objects by custom field via Stream API, How to remove duplicates using Java 8 streams based on criteria, remove elements with repeated attribute using lambda expressions, filter duplications by property name with java stream filter, Remove duplicates using lambda function in Java 8, Java 8. public int hashCode () { return customerId.hashCode (); } It is also worth noting that this is not an efficient way to remove duplicates if the list is large. combining these two, it will remove all elements (employees) whose id has been encountered before. Can we remove duplicates from it based on id property of employee. How to find duplicate objects by multiple properties and merge them? employee.removeIf(e -> !seen.add(e.getID())); What could cause the Nikon D7500 display to look like a cartoon/colour blocking? 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. Can I still have hopes for an offer as a software developer. 587), The Overflow #185: The hardest part of software is requirements, Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood, Temporary policy: Generative AI (e.g., ChatGPT) is banned, Testing native, sponsored banner ads on Stack Overflow (starting July 6), Removing duplicates from list where duplication logic is based on custom field, Remove element with duplicate property based on another property from list using java 8, Remove duplicates from a list of objects based multiple attributes in Java 8, How to remove duplicate from list of object in java using stream API, Java 8:How to remove duplicates from the List based on multiple properties preserving the order, Java stream remove duplicate list of objects of list property, Remove duplicate elements across multiple lists java 8, Java - merge two lists removing duplicates based on the value of a property. Making statements based on opinion; back them up with references or personal experience. Find centralized, trusted content and collaborate around the technologies you use most. For example I have a list of Person object and I want to remove people with the same name. More generally using streams here is complicated. (Ep. How do I sort a list of objects based on an attribute of the objects? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. This is a sample domain object class: private String mdl; private String ndc; private String gpi; private String labelName; private int seqNo; private String vendorName; The mdl, ndc, gpi, and seqNo together make up a unique record. Is there a legal way for a country to gain territory from another through a referendum? Non-definability of graph 3-colorability in first-order logic, Commercial operation certificate requirement outside air transportation, Science fiction short story, possibly titled "Hop for Pop," about life ending at age 30. If either of the address list contains same city and country which is same in other obj1, then I don't need in that list. Multiple Here, we have used the Stream class to remove duplicate elements from the arraylist. for the property Name (the same for the property Id etc. TreeSet< to Remove Duplicates from ArrayList in Java How to remove Duplicated elements from a List based on Two How to remove Duplicated elements from a List based on Two properties using Java 8 streams? If you can not or don't want to override the equals method, you can filter the stream in the following way for any property, e.g. Thanks for contributing an answer to Stack Overflow! List listWithDistinctPersons = persons.stream() //operators to remove duplicates based on person name .collect(Collectors.groupingBy(p -> p.getName())) .values() .stream() //cut short the groups to size of 1 .flatMap(group -> group.stream().limit(1)) //collect distinct users as list .collect(Collectors.toList()); Why is using a TreeSet useless for removing duplicates? What does that mean? In order to achieve this, I've written a custom collector that can be vaguely compared with Collectors.groupingBy. Wrapper is obvious, but the first one is much better. 587), The Overflow #185: The hardest part of software is requirements, Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood, Temporary policy: Generative AI (e.g., ChatGPT) is banned, Testing native, sponsored banner ads on Stack Overflow (starting July 6), Java List, Keep First Item, Remove Second Duplicate, Remove element with duplicate property based on another property from list using java 8, Remove duplicate list object value from another object list, Remove duplicates from a list of objects based multiple attributes in Java 8, How to remove duplicate from list of object in java using stream API, Java 8:How to remove duplicates from the List based on multiple properties preserving the order, Java stream remove duplicate list of objects of list property, Remove duplicate elements across multiple lists java 8, Java - merge two lists removing duplicates based on the value of a property. We can easily remove the duplicate elements from a List with the standard Java Collections Framework through a Set: public void givenListContainsDuplicates_whenRemovingDuplicatesWithPlainJava_thenCorrect() { Remove Duplicates From a List Using Plain Java. java Java Is there a distinction between the diminutive suffixes -l and -chen? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Do you need an "Any" type when implementing a statically typed programming language? This is a sample domain object class: private String mdl; private String ndc; private String gpi; private String labelName; private int seqNo; private String vendorName; The mdl, ndc, gpi, and seqNo together make up a unique record. Remove outermost curly brackets for table of variable dimension. Is there any good way to solve this? Often if you're having trouble writing an algorithm, the actual problem is that you haven't fully specified the behaviour you want, and thus your floundering is mostly down to you not fully understanding the problem, more than it is a coding issue. .> collect(HashMap::new,(m,e)->m.put(e.ge Removing All Duplicates From a List Having list of objects A from 3rd party remove all which have same A.b field for same A.id (multiple A object with same A.id in list). List personList = new ArrayList<>(); Set duplicates=personList.stream().filter(p -> Collections.frequency(personList, p) ==2) .collect(Collectors.toSet()); If objects are more than 2 then you use Collections.frequency(personList, p) >1 in filter predicate. How to remove Duplicated elements from a List based on Two properties using Java 8 streams? 1) Using .collect(Collectors.toConcurrentMap(..)).values() is a good solution, but it's annoying if you want to sort and keep the order. One way is to group the objects based on keys (requires correct implementation of equals and hashCode methods for Order): Since you need to collect duplicates only for elements which have status == COMPLETED you could use a map with an appropriate key. numbers.stream() - create a stream from the arraylist; stream.distinct() - removes duplicate elements; stream.collect(Collectors.toList()) - returns a list from the stream ): Set nameSet = new HashSet<>(); List employeesDistinctByName = employees.stream() .filter(e -> nameSet.add(e.getName())) Simple requirement of extracting a unique set of Person Names shall be achieved by mere "For-Each" and a "Set". Thanks for contributing an answer to Stack Overflow! Use java.util.Set instead of java.util.List and just add the objects to the Set. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. How to get an enum value from a string value in Java, Is there a deep meaning to the fact that the particle, in a literary context, can be used in place of . By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. There's a simpler approach using a TreeSet with a custom comparator. I have a list of complex objects that have multiple nested objects. It has to be handled through processing of a Stream? If order does not matter and when it's more performant to run in parallel, Collect to a Map and then get values: There are a lot of good answers here but I didn't find the one about using reduce method. Java remove entries from list where certain attributes are duplicated. The neuroscientist says "Baby approved!" Objects in the list should be removed if they have both the same name and ID. Please see my edit in question, this will remove all the duplicates. Java remove entries from list where certain attributes are duplicated, Relativistic time dilation and the biological process of aging. removeIf w What does "Splitting the throttles" mean? It should remove all the duplicate records with the same name and having value == null. @skiwi: do you think there is a way to implement, @Holger I may have been wrong there as I hadn't thought abou the overhead, And obviously it messes up the original order of the list, @DanielEarwicker this question is about "distinct by property". com.google.common.base.Equivalence.wrap(S) and com.google.common.base.Equivalence.Wrapper.get() could help too. What languages give you access to the AST to modify during compilation? So in this case, it should remove records with ID 3, 4, and 7. It then follows that constructing a set of size n has time complexity O(n log(n)). java To subscribe to this RSS feed, copy and paste this URL into your RSS reader. The simplest would be to override equals & hash code, and you only need LinkedHashSet then it would be List filteredStudents = new LinkedList<> (new This can be achieved with having a filter with its own Set: Edit: Non-definability of graph 3-colorability in first-order logic. Removing Duplicates Using Plain Java A simple way is to remove the duplicates to clean up the list using List.contains () method. You can get a stream from the List and put in in the TreeSet from which you provide a custom comparator that compares id uniquely. Then if you