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Object Oriented Programming Articles
Page 223 of 589
Use 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"); ...
Read MoreFetch key-valuepair from Java LinkedHashSet
To fetch LinkedHashSet key-value pair in Java, use the entrySet() method.Let us first create LinkedHashSet and add some elements −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");Now, fetch a key-value pair −l.entrySet()The following is an example to fetch key-value pair from LinkedHashSet −Exampleimport java.util.*; 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 MoreCreate a TreepMap in Java and add elements
Let us create TreeMap in Java. It stores unique elements in ascending order −TreeMap m = new TreeMap();Now let us add some elements −m.put(1, "PHP"); m.put(2, "jQuery"); m.put(3, "JavaScript"); m.put(4, "Ruby"); m.put(5, "Java"); m.put(6, "AngularJS"); m.put(7, "ExpressJS");The following is an example to create a TreeMap −Exampleimport java.util.*; public class Demo { public static void main(String args[]) { TreeMap m = new TreeMap(); m.put(1, "PHP"); m.put(2, "jQuery"); m.put(3, "JavaScript"); m.put(4, "Ruby"); m.put(5, "Java"); m.put(6, "AngularJS"); m.put(7, ...
Read MoreCreate a TreeMap in Java and add key-value pairs
A TreeMap cannot contain duplicate keys. TreeMap cannot contain the null key. However, It can have null values.Let us first see how to create a TreeMap −TreeMap m = new TreeMap();Add some elements in the form of key-value pairs −m.put(1, "India"); m.put(2, "US"); m.put(3, "Australia"); m.put(4, "Netherlands"); m.put(5, "Canada");The following is an example to create a TreeMap and add key-value pairs −Exampleimport java.util.*; public class Demo { public static void main(String args[]) { TreeMap m = new TreeMap(); m.put(1, "India"); m.put(2, "US"); m.put(3, "Australia"); ...
Read MoreJava Program to remove a key from a TreeMap only if it is associated with a given value
Use the remove() method to remove a key from a TreeMap only if it is associated with a given value. Let us first create a TreeMap and add some elements −TreeMap m = new TreeMap(); m.put(1, "India"); m.put(2, "US"); m.put(3, "Australia"); m.put(4, "Netherlands"); m.put(5, "Canada");To remove a key, set the key and the associated value here. If the associate value exists, then the key will get removed −m.remove(3, "Australia")The following is an example to remove a key from a TreeMap only if it is associated with a given value −Exampleimport java.util.*; public class Demo { public static void main(String ...
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