This is a drive method for two other classes. which i posted here https://codereview.stackexchange.com/questions/33148/book-program-with-arraylist I need some help for the private static ArrayList getAuthors(String authors) method. I am kind a beginner. so please help me finish this drive method. or give me some directions. Instruction some of the elements of the allAuthors array contain asterisks … Read more
Our variable: To store: To add numbers one and one, you can do something like this: In Java 8 you can use putIfAbsent to add the list if it did not exist already: Use the map.entrySet() method to iterate on:
I am meant to create a simple insertion sort method which sorts a series of generic names into alphabetical order. This should be simple, and I have already reviewed many other examples of insertion sort online, including on this site, yet I still cannot seem to obtain the correct output despite comparing my code, line-by-line, … Read more
I am working on an assignment and I have run into a few problems. Here is the Assignment Question and what I’ve done so far and my question. Complete ShoppingCart.java as follows: Declare and instantiate a variable cart to be an empty ArrayList that can hold Product objects. Remember to import ArrayList. Comments in the … Read more
First of all, for initializing a container you cannot use a primitive type (i.e. int; you can use int but as you want just an array of integers, I see no use in that). Instead, you should use Integer, as follows: For adding elements, just use the add function: Last, but not least, for printing the ArrayList you may use the build-in functionality … Read more
The source code for clear(): The source code for removeAll()(As defined in AbstractCollection): clear() is much faster since it doesn’t have to deal with all those extra method calls. And as Atrey points out, c.contains(..) increases the time complexity of removeAll to O(n2) as opposed to clear‘s O(n).
You need to add it like this.
I don’t understand the problem you have since an ArrayList implements a List with List being an interface. You can change this line to:
ArrayList<ArrayList<String>> array = new ArrayList<ArrayList<String>>(); Depending on your requirements, you might use a Generic class like the one below to make access easier:
Try this: which returns a fixed size list. If you need an expandable list, pass this result to the ArrayList constructor: