arraylist

问题 I want to save my ArrayList<HashMap<String, String>> mylist = new ArrayList<HashMap<String, String>>() in SQLite database and later retrieve it to display the items stored in it. How can I achieve this? Please provide examples. Thanks in Advance :) 回答1: Tutorial Link Please refer to the link above. I has a working example of using HashMap for SqLite operations using SQliteOpenHelper. It has one insertion at a time, but you might wanna create a loop, if you wish to insert them all in one

问题 I have this list: List<Country> countryList = new ArrayList<Country>(); And I want to sort the countries by their name, by using the method getCountry() . How can achieve this? UPDATE: public class Country implements Comparable @Override public int compareTo(Object another) { // TODO Auto-generated method stub return 0; } Can you tell how to compare them to get it sorted by Strings? Argentina, Austria, Brazil, etc. 回答1: There are two ways: Have Country implement the java.util.Comparable

问题 I'm trying to sort my arrayList by date. I stored the date on Firebase each time I receive a notification and is retrieved from there. I'm using Collections.sort but I don't know how to implement onto my codes as my date format starts with a number in a string format like "12 Jul 2017 at 12:00am". I've seen some examples of this on stackoverflow but I don't know how to make it work in my case. I will post screenshots and my codes below. The dates are not sorted. NotificationFragment.java

问题 I want to make a Deep Copy of some Object[] and ArrayList How can i do that (without looping , and calling clone) There aren't standard utils for doing this? Thanks João 回答1: None trivial objects need to provide some to support copying: even if that is in the form of implementing Clone or Serialize. This is more or less why there is no built in method and the loop is unavoidable. If it is all your own code then I would recommend a copy constructor over either clone or serialize/deserialize as

问题 I have an arraylist of strings "abcde" I want to a method to return another arraylist with all the possible combination of a given arraylist (ex:ab,ac,ad...) in C# anyone knows a simple method? NB: all possible combinations of length 2, and would be better if the length is variable(can be changed) 回答1: Pertaining your comment requiring combinations of length two: string s = "abcde"; var combinations = from c in s from d in s.Remove(s.IndexOf(c), 1) select new string(new[] { c, d }); foreach

问题 The data which is displayed from the database in the form of listview (here listview with headers having disabled onClick of headers). I tried to display the description of the selected item from position of getView() . The list is very large so it dynamically allocates the view while scrolling & the position gives wrong values after scrolling I watched Google I/O 2010 - The world of ListView video & it states these things. So I think I need to implement notifyDataSetChanged() or onScroll() ,

问题 This question already has answers here : When to use LinkedList over ArrayList in Java? (32 answers) Closed 4 years ago . I came across new list implementation which called GlueList I want to know when i should use over ArrayList or LinkedList. 回答1: To be honest, if you cant decide after reading info at GlueList which states in few sentences why it is better (different) and even have benchmark to see the real values and also Big-O notation - you are not in position where you have to think

问题 I am attempting a study of JavaFX because I want to use it as the GUI of my program. My question is essentially a conceptual one: To date my program is mostly the "Model" part of the MVC pattern; that is, almost all of my code is the OO-representation of abstractions in the sense of classes, and all of that code is logical code. Since I do not want to be the only user of my program, I want to add the "View" part of MVC so that people can easily use and manipulate the "Model" part of my

问题 I have a TreeSet which contains > 100k objects. I have another method which requires ArrayList as an param. Is there any way I can accomplish this without iterating whole TreeSet and then adding each object manually to ArrayList ? 回答1: How about this: new ArrayList<T>(set); 回答2: ArrayList has a convenience method addAll that fits the bill nicely: final Set<Object> set = ... List<Object> list = new ArrayList<Object>(someBigNum); list.addAll(set); 来源： https://stackoverflow.com/questions/9322405

问题 I have a TreeSet which contains > 100k objects. I have another method which requires ArrayList as an param. Is there any way I can accomplish this without iterating whole TreeSet and then adding each object manually to ArrayList ? 回答1: How about this: new ArrayList<T>(set); 回答2: ArrayList has a convenience method addAll that fits the bill nicely: final Set<Object> set = ... List<Object> list = new ArrayList<Object>(someBigNum); list.addAll(set); 来源： https://stackoverflow.com/questions/9322405