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Java Articles
Page 38 of 450
Insert all elements of other Collection to Specified Index of Java ArrayList
The elements of a Collection can be inserted at the specified index of the ArrayList using the method java.util.ArrayList.addAll(). This method has two parameters i.e. the specific index at which to start inserting the Collection elements in the ArrayList and the Collection itself.If there is an element already present at the index specified by ArrayList.addAll() then that element and all subsequent elements are shifted to the right to make the space for the Collection elements in the ArrayList.A program that demonstrates this is given as follow.Exampleimport java.util.ArrayList; import java.util.Vector; public class Demo { public static void main(String[] args) { ...
Read MoreSet vs HashSet vs TreeSet in Java
A Set is a generic set of values with no duplicate elements. A TreeSet is a set where the elements are sorted.A HashSet is a set where the elements are not sorted or ordered. It is faster than a TreeSet. The HashSet is an implementation of a Set.Set is a parent interface of all set classes like TreeSet, HashSet, etc.Exampleimport java.util.*; public class Demo { public static void main(String args[]) { int a[] = {77, 23, 4, 66, 99, 112, 45, 56, 39, 89}; Set s = new HashSet(); try ...
Read MoreReplace an element in an ArrayList using the ListIterator in Java
An element in ArrayList can be replaced using the ListIterator method set(). This method has a single parameter i.e. the element that is to be replaced and the set() method replaces it with the last element returned by the next() or previous() methods.A program that demonstrates this is given as follows.Exampleimport java.util.ArrayList; import java.util.ListIterator; public class Demo { public static void main(String[] args) { ArrayList aList = new ArrayList(); aList.add("Amanda"); aList.add("Taylor"); aList.add("Justin"); aList.add("Emma"); aList.add("Peter"); System.out.println("The ArrayList elements are: ...
Read MoreIterate through a LinkedList using an Iterator in Java
An Iterator can be used to loop through an LinkedList. The method hasNext( ) returns true if there are more elements in LinkedList and false otherwise. The method next( ) returns the next element in the LinkedList and throws the exception NoSuchElementException if there is no next element.A program that demonstrates this is given as follows.Exampleimport java.util.LinkedList; import java.util.Iterator; public class Demo { public static void main(String[] args) { LinkedList l = new LinkedList(); l.add("John"); l.add("Sara"); l.add("Susan"); l.add("Betty"); l.add("Nathan"); ...
Read MoreUse ListIterator to traverse an ArrayList in the forward direction in Java
A ListIterator can be used to traverse the elements in the forward direction as well as the reverse direction in the List Collection. So the ListIterator is only valid for classes such as LinkedList, ArrayList etc.The method hasNext( ) in ListIterator returns true if there are more elements in the List and false otherwise. The method next( ) returns the next element in the List and advances the cursor position.A program that demonstrates this is given as follows −Exampleimport java.util.ArrayList; import java.util.ListIterator; public class Demo { public static void main(String[] args) { ArrayList aList = new ...
Read MoreUse ListIterator to traverse an ArrayList in the reverse direction in Java
A ListIterator can be used to traverse the elements in the forward direction as well as the reverse direction in the List Collection. So the ListIterator is only valid for classes such as LinkedList, ArrayList etc.The method hasPrevious( ) in ListIterator returns true if there are more elements in the List while traversing in the reverse direction and false otherwise. The method previous( ) returns the previous element in the List and reduces the cursor position backward.A program that demonstrates this is given as follows −Exampleimport java.util.ArrayList; import java.util.ListIterator; public class Demo { public static void main(String[] args) { ...
Read MoreGet Size of Java LinkedHashMap
The size() method is used to get the size of LinkedHashMap in Java.Create a LinkedHashMap and add some elements to it −LinkedHashMap l = new LinkedHashMap(); l.put("1", "Jack"); l.put("2", "Tom"); l.put("3", "Jimmy"); l.put("4", "Morgan"); l.put("5", "Tim"); l.put("6", "Brad");Get the size now −l.size()The following is an example to get the size of LinkedHashMap −Exampleimport java.util.LinkedHashMap; public class Demo { public static void main(String[] args) { LinkedHashMap l = new LinkedHashMap(); l.put("1", "Jack"); l.put("2", "Tom"); l.put("3", "Jimmy"); l.put("4", "Morgan"); l.put("5", "Tim"); ...
Read MoreCheck if a particular element exists in Java LinkedHashSet
Use the contains() method to check if a specific element exists in LinkedHashSet or not.Let us first create a LinkedHashSet and add some elements −LinkedHashSet l = new LinkedHashSet(); l.add(new String("1")); l.add(new String("2")); l.add(new String("3")); l.add(new String("4")); l.add(new String("5")); l.add(new String("6")); l.add(new String("7"));Now, check whether it contains element “5” or not −l.contains("5")The following is an example to check if a particular element exists in LinkedHashSet −Exampleimport java.util.*; public class Demo { public static void main(String[] args) { LinkedHashSet l = new LinkedHashSet(); l.add(new String("1")); l.add(new String("2")); l.add(new ...
Read MoreConvert a Set into a List in Java
First, create a Set and add elements −Set s = new HashSet(); s.add("P"); s.add(new Date()); s.add(new Long(898999)); s.add("Q"); s.add("R"); s.add(new Integer(1));Convert the above Set to a List −List l = new ArrayList(s);The following is an example to convert a set into a list in Java −Exampleimport java.util.ArrayList; import java.util.Date; import java.util.List; import java.util.Set; import java.util.HashSet; public class Demo { public static void main(String[] args) { Set s = new HashSet(); s.add("P");; s.add(new Date()); s.add(new Long(898999)); s.add("Q"); s.add("R"); s.add(new ...
Read MoreCopy all the elements from one set to another in Java
Use the clone() method to copy all elements from one set to another.First HashSet −HashSet set = new HashSet (); set.add("One"); set.add("Two");Create another set and clone first set into the second −HashSet newSet = new HashSet ();Copy (clone) all elements to the second set −newSet = (HashSet)set.clone();The following is an example to copy all elements from one set to another −Exampleimport java.util.*; public class Demo { public static void main(String args[]) { HashSet set = new HashSet (); HashSet newSet = new HashSet (); set.add("One"); ...
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