So this question is not unrelated to Java, and actually the problem he is facing precisely exists in Java as well when iterating over lists while also updating. a c The author of this code snippet probably expected it to iterate over each element of the list, print it out, then remove it so that the list ends up empty (this may be desirable if, for example, you are removing items conditionally). You're not modifying the list in any way at all. Problems removing element while iterating over list. Lists 2.1.1. Change the field label name in lightning-record-form component. See. It is. groovy - Change all list items during iteration - Stack Overflow Change all list items during iteration Ask Question Asked 4 years, 10 months ago Modified Viewed 142 times -1 Problem I need to change all list items during a loop. Not the answer you're looking for? The map's values will be a list of instances of File, so Collection#max will let you search for the one with the highest revision number. Knowing the sum, can I solve a finite exponential series for r? This was a simple example based on different code where the iteration variable is used. Knowing the sum, can I solve a finite exponential series for r? Does a Wand of Secrets still point to a revealed secret or sprung trap? python - Modify a list while iterating - Stack Overflow By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. But can I modify an item in a list I'm iterating over if I do not change the list length? Thanks! 12 This question already has answers here : How to modify list entries during for loop? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. [java] In Java, can you modify a List while iterating through it? How do I store ready-to-eat salad better? @sharonbn Sorry. AC line indicator circuit - resistor gets fried. What's the meaning of which I saw on while streaming? Groovy performs dynamic dispatch to resolve operator overloading. Connect and share knowledge within a single location that is structured and easy to search. then you can create a new list. Find centralized, trusted content and collaborate around the technologies you use most. They are typically a bit slower than non-concurrent collections, but faster than the synchronized collection wrappers if there is significant contention. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. There is nothing wrong with the idea of modifying an element inside a list while traversing it (don't modify the list itself, that's not recommended), but it can be better expressed like this: At the end the whole list will have the letter "D" as its content. 588), Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood, Temporary policy: Generative AI (e.g., ChatGPT) is banned. So why don't you create the List inside the Loop, fill it, and use it, then go to the next iteration. It can use classic for, do-while, while, for-in, each, or times loop. Use a while loop that checks for the truthfulness of the array: And it should do it without any errors or funny behaviour. >>> l = list('abcdefab') >>> for i in l: if l.count(i) > 1: l.remove(i). By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Loop over multiple arrays simultaneously - Rosetta Code This slice syntax makes a copy of the list and does what you want: Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Will using ConcurrentLinkedList cause any disadvantages like lower performance or anything. Find centralized, trusted content and collaborate around the technologies you use most. Millions? While first time I mean for first iterator its working fine but the next iterator i.e. @aps, No you cannot add elements. Loops a control flow statement for traversing or iterating items in a collection, array, list, set, etc. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Is Benders decomposition and the L-shaped method the same algorithm? HashMap replace(key, value) method in Java with Examples Not the answer you're looking for? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Try coding a list-like container such that, e.g, The iterator doesn't own nor hold any items -- it reaches into the list (at the iterator's current index --, Also, if you just want to iterate over integers, better still to use, @wsysuper try to print your suggestion and you'll see why it's no good :). 588), Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood, Temporary policy: Generative AI (e.g., ChatGPT) is banned. Groovy remove Collection item while iterating - Stack Overflow According to the documentation, you can use a half-opened range: First of all, in Groovy you don't need to specify private attribute because it is made by default. I just thought what will happen if inside the for-loop I begin creating many additional fields to an object (or any other operations that will consume too much memory and thus needed to be reallocated) before I finish with this object and go to the next one. In your code you are assigning the result to the local variable. How to explain that integral calculate areas? rev2023.7.13.43531. How do I split a list into equally-sized chunks? Improve The Performance Of Multiple Date Range Predicates, Incorrect result of if statement in LaTeX, Sheep's wool type hair clumping and parting with geometry nodes, blender 3.6, "He works/worked hard so that he will be promoted.". How to test my camera's hot-shoe without a flash at hand. Can you add the missing code so that is runnable? Why don't the first two laws of thermodynamics contradict each other? Improve The Performance Of Multiple Date Range Predicates. Is tabbing the best/only accessibility solution on a data heavy map UI? Differences between Oracle JDK and OpenJDK, Optimize the speed of a safe prime finder in C. What's the meaning of which I saw on while streaming? What changes in the formal status of Russia's Baltic Fleet once Sweden joins NATO? Is tabbing the best/only accessibility solution on a data heavy map UI? 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. If you also need the ability to add elements while iterating, use a ListIterator. Does a Wand of Secrets still point to a revealed secret or sprung trap? This is correct, but perhaps confusing to some people. These avoid the need to throw exceptions by providing weaker models of consistency for the iterators. List (Groovy JDK enhancements) - Apache Groovy java - How to modify a Collection while iterating using for-each loop I updated my post with real list declaration. Read through those APIs I posted as well as the List JDK. What are the reasons for the French opposition to opening a NATO bureau in Japan? Iterating on a list 2.1.4. What did you expect? Note that it is necessary to cast b to Object explicitly. Maybe you can express your desires with a while? Sum of a range of a sum of a range of a sum of a range of a sum of a range of a sum of. rev2023.7.13.43531. I want to make breaking changes to my language, what techniques exist to allow a smooth transition of the ecosystem? You ask specifically about "while iterating", are you trying to do something with/too each object? How to read and write a Properties File in Groovy with examples The elements in a Map collection are accessed by a key value. 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. If im applying for an australian ETA, but ive been convicted as a minor once or twice and it got expunged, do i put yes ive been convicted? Not the answer you're looking for? Although be aware that is not safe to view and edit any collection at the same time. Is that allowed? Groovy remove Collection item while iterating, removing a specific value from a groovy list, Remove items in list before a matched item groovy, How to remove Duplicate Values from a list in groovy. Thanks for contributing an answer to Stack Overflow! The map's values will be a list of instances of File, so Collection#max will let you search for the one with the highest revision number. [EDIT] Merge 2 answers for same question (Efficiency design considerations). Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing. For example if your collection is a list, than you can make a new ArrayList(originaList) and iterate over that. Cat may have spent a week locked in a drawer - how concerned should I be? Groovy lists are plain JDK java.util.List, as Groovy doesn't define its own collection classes. I resolved that I would never do it under any circumstance. When we insert into a Map collection, two values are required: the key and the value. Why speed of light is considered to be the fastest? Thanks for contributing an answer to Stack Overflow! Is there any workaround? As long as you don't directly change the actual list, you're fine. And why doesn't it give exceptions? Find centralized, trusted content and collaborate around the technologies you use most. Never alter the container you're looping on, because iterators on that container are not going to be informed of your alterations and, as you've noticed, that's quite likely to produce a very different loop and/or an incorrect one. But I have quite a number of collections, so I will have to create a lot of redundant toRemove collections for every collection I have. list = [1,2,3,4] list.remove (2) assert list == [1,2,4] // or with a loop list = [1,2,3,4] i = list.iterator () 2.times { i.next () } i.remove () assert list == [1,2,4] If you want to remove the (first) item with value 2, you can do. Does attorney client privilege apply when lawyers are fraudulent about credentials? What is the reason behind this kind of behaviour when modifying elements while iterating through a python list. UPD. Solution 1 You are not modifying the list, so to speak. Find centralized, trusted content and collaborate around the technologies you use most. Define variable in LaTeX with value contain mathematical operator. Can I do a Performance during combat? Thanks. Conclusions from title-drafting and question-content assistance experiments How to modify list elements while iterating over the list? an effectively immutable copy Since: 1.0 See Also: List#asUnmodifiable () public List asReversed () Creates a view list with reversed order, and the order of original list will not change. Code - Please, may, additionally, everyone note that the List.remove(int) method differs from the List.remove((Object) int) method.
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