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Object Oriented Programming Articles
Page 220 of 589
Copy all elements of Java LinkedHashSet to an Object Array
First, create a LinkedHashSet and add 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, copy it to an object array like this −// copying Object[] arr = l.toArray();The following is an example to copy all elements of a LinkedHashSet to an object array −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")); ...
Read MoreCreate a TreeSet in Java
Create a TreeSet and add elements −TreeSet tSet = new TreeSet(); tSet.add("TV"); tSet.add("Radio"); tSet.add("Internet");Iterate through the elements −Iterator i = tSet.iterator(); while(i.hasNext()){ System.out.println(i.next()); }The following is an example to create a TreeSet −Exampleimport java.util.*; public class Demo { public static void main(String args[]){ TreeSet tSet = new TreeSet(); tSet.add("TV"); tSet.add("Radio"); tSet.add("Internet"); Iterator i = tSet.iterator(); while(i.hasNext()){ System.out.println(i.next()); } } }OutputInternet Radio TV
Read MoreCheck two ArrayList for equality in Java
Two ArrayList can be compared to check if they are equal or not using the method java.util.ArrayList.equals(). This method has a single parameter i.e. an ArrayList that is compared with the current object. It returns true if the two ArrayList are equal and false otherwise.A program that demonstrates this is given as follows −Exampleimport java.util.ArrayList; import java.util.List; public class Demo { public static void main(String[] args) { List aList1 = new ArrayList(); aList1.add("Sun"); aList1.add("Moon"); ...
Read MoreSort items in a Java TreeSet
First, create a TreeSet and add elements to it −TreeSet set = new TreeSet(); set.add("65"); set.add("45"); set.add("19"); set.add("27"); set.add("89"); set.add("57");Now, sort it in ascending order, which is the default −Iterator i = set.iterator(); while(i.hasNext()){ System.out.println(i.next()); }If you want to sort in descending order, then use the descendingIterator() method −Iterator j = set.descendingIterator(); while(j.hasNext()) { System.out.println(j.next()); }The following is an example to sort items in a TreeSet in ascending and descending order −Exampleimport java.util.*; public class Demo { public static void main(String args[]){ TreeSet set = ...
Read MoreGet SubList from LinkedList in Java
The subList of a LinkedList can be obtained using the java.util.LinkedList.subList(). This method takes two parameters i.e. the start index for the sub-list(inclusive) and the end index for the sub-list(exclusive) from the required LinkedList. If the start index and the end index are the same, then an empty sub-list is returned.A program that demonstrates this is given as follows −Exampleimport java.util.LinkedList; import java.util.List; public class Demo { public static void main(String[] args) { LinkedList l = new LinkedList(); l.add("John"); ...
Read MoreNavigableSet Class lower() method in Java
The lower() method of NavigableSet returns the greatest element strictly less than the given element i.e. 35 here −lower(35);The following is an example to implement the lower() method in Java −Exampleimport java.util.NavigableSet; import java.util.TreeSet; public class Demo { public static void main(String[] args) { NavigableSet set = new TreeSet(); set.add(10); set.add(25); set.add(40); set.add(55); set.add(70); set.add(85); set.add(100); System.out.println("Returned Value = " + set.lower(35)); } }OutputReturned Value = 25
Read MoreHow to use subSet() method of Java NavigableSet Class
Use the subset() method to get elements from a limit. At first, create NavigableSet and add elements −NavigableSet set = new TreeSet(); set.add(10); set.add(25); set.add(40); set.add(55); set.add(70); set.add(85);Now, use the subset() method −set.subSet(40, 85)The following is an example to implement subset() method of Java NaviagbleSet class −Exampleimport java.util.NavigableSet; import java.util.TreeSet; public class Demo { public static void main(String[] args) { NavigableSet set = new TreeSet(); set.add(10); set.add(25); set.add(40); set.add(55); set.add(70); set.add(85); set.add(100); System.out.println("Returned Value = " + set.subSet(40, 85)); } }OutputReturned Value = [40, 55, 70]
Read MoreNavigableMap size() Method in Java
To get the size of NavigableMap, use the size() method. It returns the count of elements in the NavigableMap.Let us first create a NavigableMap and add some elements to it −NavigableMap n = new TreeMap(); n.put(5, "Tom"); n.put(9, "John"); n.put(14, "Jamie"); n.put(1, "Tim"); n.put(4, "Jackie"); n.put(15, "Kurt"); n.put(19, "Tiger"); n.put(24, "Jacob");Now, get the size −n.size();The following is an example to implement the size() method to get the size of the NavigableMap −Exampleimport java.util.*; public class Demo { public static void main(String[] args) { NavigableMap n = new TreeMap(); ...
Read MoreRetrieve environment variables with Java Map Collection
First, use the getenv() method to get the environment variables −System.out.println("PATH = " + System.getenv("PATH"));Now, get the key and value. Loop through to get the list of environment variables −Map e = System.getenv(); for (Iterator i = e.entrySet().iterator(); i.hasNext();) { Map.Entry mapEntry = (Map.Entry) i.next(); System.out.println(mapEntry.getKey() + " = " + mapEntry.getValue()); }The following is an example to retrieve environment variables with Map Collection −Exampleimport java.util.Iterator; import java.util.Map; public class Demo { public static void main(String args[]) { System.out.println("PATH = " + System.getenv("PATH")); ...
Read MoreCreate a HashMap in Java
To create a HashMap, use the HashMap map and new −HashMap hm = new HashMap();Now, set elements −hm.put("Finance", new Double(999.87)); hm.put("Operations", new Double(298.64)); hm.put("Marketing", new Double(39.56));Display the elements now using the following code −Exampleimport java.util.*; public class Demo { public static void main(String args[]) { // Create a hash map HashMap hm = new HashMap(); // Put elements to the map hm.put("Finance", new Double(999.87)); hm.put("Operations", new Double(298.64)); ...
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