Using collections framework in Java, a developer has to use loops and make repeated checks. Another concern is efficiency; as multi-core processors are available at ease, a Java developer has to write parallel code processing that can be pretty error-prone. To resolve such issues, Java 8 introduced the concept of stream that lets the developer … Read more
you have two approaches: ArrayList<String> ar = new ArrayList(); ar.add(“UserId”); //adding item to arraylist ar.add(“Directory”); ar.add(“Username”); ar.add(“PhoneNumber”); // approach one using iteration for (Iterator<String> it = ar.iterator(); it.hasNext(); ) { String f = it.next(); if (f.equals(“UserId”)) System.out.println(“UserId found”); } // approach two using a colletion which supports fetching element by key Map<String,String> myMap=new HashMap<>(); for(String … Read more
Introduction If you are looking for a way to get substring items within an ArrayList in Java, then you have come to the right place. In this article, we will discuss how to get substring items within an ArrayList in Java. We will look at different methods of doing this, such as using the subList() … Read more
In short: primitive types and “Primitive wrappers (Integer, Long, Short, Double, Float, Character, Byte, Boolean)” can not be altered via reference. Check http://en.wikipedia.org/wiki/Immutable_object for Details 5 solved Pass by Ref Java. Integer ins’t modified, Collection is modified, Why? [duplicate]
Currently I am looking for best replacement of HashMap becuase of memory overhead and I need faster update and retrieval of data. I don’t know if a Trie will give you a smaller memory overhead than a HashMap. It depends on the size and distribution of the keys, and on how you implement the Trie. … Read more
The Comparable interface is used to compare two objects and their order. As per the Javadocs, the compareTo method should return 0 if the two objects are equal, any negative number if this object is “smaller” than the specified other, and any positive number if this object is “larger” than the specified other. What “smaller” … Read more
A Map is a key-value pair, i.e., a value is associated to a key. Your code can be refactored as follows: Map<String, Object> details = taskManager.getFormDetails(appSessionURI, accessToken); //System.out.println(“Details :” + details); String fileName = (String)details.get(“fileName”); String refGene = (String)details.get(“refgene”); 3 solved Retrieve value in HashMap [closed]
Have you tried looking at ListViewItem and then populating a list view? If not then you can easily use a list of arrays, or even populate it in a foreach loop like bellow? foreach( var v in Muvees ) {ListViewItem movieToAdd = new ListViewItem(); movieToAdd.Text = v.movieid; movieToAdd.SubItems.Add(v.rating); movieToAdd.SubItems.Add(v.movieName); listOfMovies.Items.Add( movieToAdd ).BackColor = Color.Green;} //add … Read more
This code declares a variable tables of type List<Data>, and initialize it to null. (I change your data to Data to match the java convention) I think you’re in trouble with the <Data> part. So let me say: List is a generic class, which can be parametrized with another type. You can write List<String> or … Read more
First take the words of str in an array. Then check whether the words in the forward order and the reverse order are same. String[] words = str.split(” “); //splits at spaces boolean flag = true; int i, last = words.length – 1; for(i = 0; i <= last/2; i++){ if(!words[i].equalsIgnoreCase(words[last – i])){ flag = … Read more
As already mentioned in a comment by the user “soon”, this problem can be easily solved with flatMap and map: List<TestSession> list = mapList.entrySet().stream() .flatMap(e1 -> e1.getValue().stream() .map(e2 -> new TestSession(e1.getKey(), e2.getKey(), e2.getValue()))) .collect(Collectors.toList()); solved Convert Map to List with new java 8 streams
The sorting algorithm for Arrays.sort(int[] a) is a tuned quicksort. Ref: https://docs.oracle.com/javase/6/docs/api/java/util/Arrays.html#sort(int[]) Read this article: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.14.8162&rep=rep1&type=pdf for understanding the Quick-sort used in Array.sort() by JON L. BENTLEY & M. DOUGLAS McILROY In Java 7 pivot dual quick-sort algorithm is used for Arrays.sort(int[] a) i.e. refer this: What’s the difference of dual pivot quick sort and … Read more
You cannot use a dictionary of Booleans, because it is limited to only two values. This will inevitably lead to key collisions, because you plan to add more than two items to it. Good news is that you do not need a dictionary anyway, because you use it as a collection of tuples. This will … Read more
Neither. Using a loop has less overhead than LINQ, so that is a good start. Use the < operator in the loop condition, that is the standard way of writing such a loop, so it’s more likely that the compiler will recognise it and optimise it properly. Using Math.Pow to square a number is not … Read more
Depending on the underlying implementation a remove in a List / Set can be O(1), O(n) or O(log n) (or some other even bigger complexity for esoteric implementations). ArrayList remove is O(n) on everything but the last element. Removing the last element in an ArrayList is O(1) (decrementing the size counter and setting the element … Read more