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Java Articles
Page 66 of 450
How to convert Float array list to float array in Java?
Let us first create a float array list −ArrayList < Float > arrList = new ArrayList < Float > (); arrList.add(5.2 f); arrList.add(10.3 f); arrList.add(15.3 f); arrList.add(20.4 f);Now, convert the float array list to float array. At first, we have set the same size to float array i.e. the same number of elements. After that, we have assigned each value −final float[] arr = new float[arrList.size()]; int index = 0; for (final Float value: arrList) { arr[index++] = value; }Exampleimport java.util.ArrayList; public class Demo { public static void main(String[] args) { ArrayListarrList = new ArrayList(); ...
Read MoreHow can I generate random booleans in Java?
To generate random booleans like TRUE or FALSE, at first create a new Random object −Random randNum = new Random();Now, loop through the count of booleans you want and generate random booleans with nextBooleans() method −for (int i = 1; i
Read MoreJava Program to find keys from a Linked HashMap and store it in a list
Let us first create a LinkedHashMap with key-value pair −Mapmap = new LinkedHashMap(); map.put("1", "Katie"); map.put("2", "Peter"); map.put("3", "Amy"); map.put("4", "Kane"); map.put("5", "Colin"); map.put("6", "Andre"); map.put("7", "Pollard"); map.put("8", "David"); map.put("9", "Jofra"); map.put("10", "Akila");Now, create a new List and store the keys in it for the above Map −Listlist = new ArrayList(); list.addAll(map.keySet());Exampleimport java.util.ArrayList; import java.util.LinkedHashMap; import java.util.List; import java.util.Map; public class Demo { public static void main(String[] args) { Mapmap = new LinkedHashMap(); map.put("1", "Katie"); map.put("2", "Peter"); map.put("3", "Amy"); map.put("4", "Kane"); ...
Read MoreHow to fill multiple copies of specified Object to a List in Java
To fill multiple copies of specified object to a list means let’s say you have an element 100 and want to display it 10 times. For this, let us see an example.The following is our list and iterator. We have used nCopiec Collections method to set the elements and how many copies you want −Listlist = Collections.nCopies(10, 100); Iteratoriterator = list.iterator();After that display the multiple copies −while (iterator.hasNext()) System.out.println(iterator.next());Exampleimport java.util.Collections; import java.util.Iterator; import java.util.List; public class Demo { public static void main(String[] args) { Listlist = Collections.nCopies(10, 100); Iteratoriterator = list.iterator(); ...
Read MoreJava Program to sort a List in case insensitive order
Let’s say your list is having the following elements −P, W, g, K, H, t, ETherefore, case sensitive order means, capital and small letters will be considered irrespective of case. The output would be −E, g, H, K, P, t, WThe following is our array −String[] arr = new String[] { "P", "W", "g", "K", "H", "t", "E" };Convert the above array to a List −Listlist = Arrays.asList(arr);Now sort the above list in case insensitive order −Collections.sort(list, String.CASE_INSENSITIVE_ORDER);Exampleimport java.util.Arrays; import java.util.Collections; import java.util.List; public class Demo { public static void main(String[] argv) throws Exception { String[] ...
Read MoreJava Program to remove an element from List with ListIterator
Let’s say the following is our List with elements −ArrayList < String > arrList = new ArrayList < String > (); arrList.add("Jack"); arrList.add("Tom"); arrList.add("Brad"); arrList.add("Amy"); arrList.add("Ben"); arrList.add("Peter"); arrList.add("Katie"); arrList.add("Tim");Now, use the listIterator(). The next() method returns the next element in the List. Hoverer, remove an element using remove() method −ListIteratoriterator = arrList.listIterator(); iterator.next(); iterator.remove();Exampleimport java.util.ArrayList; import java.util.ListIterator; public class Demo { public static void main(String[] args) { ArrayListarrList = new ArrayList(); arrList.add("Jack"); arrList.add("Tom"); arrList.add("Brad"); arrList.add("Amy"); arrList.add("Ben"); arrList.add("Peter"); ...
Read MoreRemove duplicate elements in Java with HashSet
Set implementations in Java has only unique elements. Therefore, it can be used to remove duplicate elements.Let us declare a list and add elements −List < Integer > list1 = new ArrayList < Integer > (); list1.add(100); list1.add(200); list1.add(300); list1.add(400); list1.add(400); list1.add(500); list1.add(600); list1.add(600); list1.add(700); list1.add(400); list1.add(500);Now, use the HashSet implementation and convert the list to HashSet to remove duplicates −HashSetset = new HashSet(list1); Listlist2 = new ArrayList(set);Above, the list2 will now have only unique elements.Exampleimport java.util.ArrayList; import java.util.HashSet; import java.util.List; public class Demo { public static void main(String[] argv) { Listlist1 = new ArrayList(); ...
Read MoreReplace an element from a Java List using ListIterator
Let us first create a Java List and add elements −ArrayList < String > list = new ArrayList < String > (); list.add("Katie"); list.add("Tom"); list.add("Jack"); list.add("Amy"); list.add("Andre"); list.add("Brad"); list.add("Peter"); list.add("Bradley");Now, use ListIterator and return the next element in the List with next() −ListIteratoriterator = list.listIterator(); iterator.next();Replace the element in the List with set() method. Here, whatever element is set will get replaced as the first element of the Iterator −iterator.set("Angelina");Exampleimport java.util.ArrayList; import java.util.ListIterator; public class Demo { public static void main(String[] args) { ArrayListlist = new ArrayList(); list.add("Katie"); list.add("Tom"); ...
Read MoreJava Program to create String to super class type mapping
Here, we have a superclass Vehicle and within that some subclasses −class Vehicle { } class Motorcycle extends Vehicle { } class Bus extends Vehicle { } class Car extends Vehicle { }Now, we will create some strings for mapping with super class type −Mapmap = new HashMap(); map.put("motorcycle", new Motorcycle()); map.put("bus", new Bus()); map.put("car", new Car());Exampleimport java.util.HashMap; import java.util.Map; class Vehicle { } class Motorcycle extends Vehicle { } class Bus extends Vehicle { } class Car extends Vehicle { } public class Demo { public static void main(String... args) { Mapmap = new HashMap(); ...
Read MoreExtract values from HashMap in Java
To extract values from HashMap, let us first create a HashMap with keys and values −HashMapm = new HashMap();Now, add some elements to the HashMap −m.put(10, 20); m.put(30, 40); m.put(50, 60); m.put(70, 80); m.put(90, 100); m.put(110, 120); m.put(130, 140); m.put(150, 160);Now, extract the values from the HashMap −for (Integer i: m.keySet()) { System.out.println(m.get(i)); }Exampleimport java.util.HashMap; public class Demo { public static void main(String args[]) { HashMapm = new HashMap(); m.put(10, 20); m.put(30, 40); m.put(50, 60); m.put(70, 80); m.put(90, 100); ...
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