arraylist

问题 I'm a bit lost on the way to make this happen the fastest. I have a large list of objects that have basic variable attributes (with getters / setters) and I need to do a search in this list to find the objects within the list that match a given parameter I have found how to do a regular list search but I need to, for example search for the value of the result of doing a call getName() for each object in the list and get objects that have a result that matches my input. Something like below

问题 Is there an expandable array class in the Java API equivalent to the Vector or ArrayList class that can be used with primitives (int, char, double, etc)? I need a quick, expandable array for integers and it seems wasteful to have to wrap them in the Integer class in order to use them with Vector or ArrayList . My google-fu is failing me. 回答1: There is unfortunately no such class , at least in the Java API. There is the Primitive Collections for Java 3rd-party product. It's pretty dangerous to

问题 This question already has answers here : How do I remove repeated elements from ArrayList? (38 answers) Closed 3 years ago . ArrayList<String> values=new ArrayList<String>(); values.add("s"); values.add("n"); values.add("a"); values.add("s"); In this Array, I want to remove repeated values. 回答1: Try this... ArrayList<String> values=new ArrayList<String>(); HashSet<String> hashSet = new HashSet<String>(); hashSet.addAll(values); values.clear(); values.addAll(hashSet); Happy coding... 回答2: Try

问题 Is there a way to find the most common String in an ArrayList ? ArrayList<String> list = new ArrayList<>(); list.add("test"); list.add("test"); list.add("hello"); list.add("test"); Should find the word "test" from this list ["test","test","hello","test"] 回答1: Don't reinvent the wheel and use the frequency method of the Collections class: public static int frequency(Collection<?> c, Object o) Returns the number of elements in the specified collection equal to the specified object. More

问题 My problem: I am sending a request to a servlet from an AJAX function in a JSP. The servlet processes the data and returns a ArrayList . My question is how to handle the ArrayList inside AJAX, and display it as a table in same JSP. The code is function ajaxFunction ( ) { // var url= codeid.options[codeid.selectedIndex].text; url="mstParts?caseNo=9&cdid=QCYST0020E1"; // alert(cid); var httpRequest; if (window.XMLHttpRequest) { httpRequest = new XMLHttpRequest(); } else if (window.ActiveXObject

问题 On CodeReview I posted a working piece of code and asked for tips to improve it. One I got was to use a boolean method to check if an ArrayList had an even number of indices (which was required). This was the code that was suggested: private static boolean isEven(int number) { return (number & 1) == 0; } As I've already pestered that particular user for a lot of help, I've decided it's time I pestered the SO community! I don't really understand how this works. The method is called and takes

问题 I have seen many parcelable examples so far, but for some reason I can't get it to work when it gets a bit more complex. I have a Movie object, which implements Parcelable. This book object contains some properties, such as ArrayLists. Running my app results in a NullPointerException when executing the ReadTypedList ! I'm really out of ideas here public class Movie implements Parcelable{ private int id; private List<Review> reviews private List<String> authors; public Movie () { reviews = new

问题 I have a function which manipulates a very large list, exceeding about 250,000 items. For the majority of those items, it simply replaces the item at position x. However, for about 5% of them, it must remove them from the list. Using a LinkedList seemed to be the most obvious solution to avoid expensive removals. However, naturally, accessing a LinkedList by index becomes increasingly slow as time goes on. The cost here is minutes (and a lot of them). Using an Iterator over that LinkedList is

问题 I am attempting to create a small course aggregator program in the form of an android application. My courses are all stored in a Firebase Realtime Database, which is viewable from the firebase console and everything appears fine. The issue is that I have written a java method to connect to the DB, retrieve the data from the DB, cast the data as a Custom Java object Course , attach it to another custom Java object CourseCardModel , and then save the CourseCardModel object into an ArrayList.

问题 I am using wildcard and lower bound generics on list and yet compiler is throwing error. Code: int intStart = 0; Number num = new Integer(2); List<? super Integer> listOfNumbers = new ArrayList<>(); listOfNumbers.add(intStart); listOfNumbers.add(num); //throws compiler error Error : The method add(capture#8-of ? super Integer) in the type List is not applicable for the arguments (Number) With List<? super Integer> , I should have been allowed to add any objects of type Integer or its