The floorKey() method is used to get floor key i.e. to return the greatest key less than or equal to the given key, or null if there is no such key.The following is an example to get floor key from NavigableMapExample Live Demoimport java.util.*; public class Demo {    public static void main(String[] args) {       NavigableMap n = new TreeMap();       n.put("A", 498);       n.put("B", 389);       n.put("C", 868);       n.put("D", 988);       n.put("E", 686);       n.put("F", 888);       n.put("G", 999);       ... Read More

The first and last elements of a Linked List can be obtained using the methods java.util.LinkedList.getFirst() and java.util.LinkedList.getLast() respectively. Neither of these methods require any parameters.A program that demonstrates this is given as followsExample Live Demoimport java.util.LinkedList; 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 More

The lowerEntry() method in NavigabelMap returns a key-value mapping associated with the greatest key strictly less than the given key.The following is an example to implement lowerEntry() methodExample Live Demoimport java.util.*; public class Demo {    public static void main(String[] args) {       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");       System.out.println("NavigableMap elements..."+n);       System.out.println("Lower Entry is ... Read More

The higherEntry() method in NavigableMap returns a key-value mapping associated with the least key strictly greater than the given key.The following is an example to implement higherEntry() method −Example Live Demoimport java.util.*; public class Demo {    public static void main(String[] args) {       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");       System.out.println("NavigableMap elements..."+n);       System.out.println("Higher Entry ... Read More

Use the put() method to add elements to LinkedHashMap collection.First, let us create a LinkedHashMap −LinkedHashMap l = new LinkedHashMap();Now, add elements −l.put("1", "Jack"); l.put("2", "Tom"); l.put("3", "Jimmy"); l.put("4", "Morgan"); l.put("5", "Tim"); l.put("6", "Brad");The following is an example to add elements to LinkedHashMap collection −Example Live Demoimport 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"); ... Read More

Firstly, create a HashMap −HashMap hm = new HashMap();Add some elements to the HashMap −hm.put("Shirts", new Integer(700)); hm.put("Trousers", new Integer(600)); hm.put("Jeans", new Integer(1200)); hm.put("Android TV", new Integer(450)); hm.put("Air Purifiers", new Integer(300)); hm.put("Food Processors", new Integer(950));Now, sort the HashMap based on keys using TreeMap −Map sort = new TreeMap(hm); System.out.println("Sorted Map based on key = "+sort);The following is an example to sort HasMap based on keys −Example Live Demoimport java.util.*; public class Demo { public static void main(String args[]) { HashMap hm = new HashMap(); hm.put("Shirts", new ... Read More

Use the contains() method to check if a particular element exists −Set hs = new HashSet(); hs.add(30); hs.add(67); hs.add(88); hs.add(33); hs.add(54); hs.add(90); hs.add(66); hs.add(79);To check for let’s say, element 89, use the contains() method −hs.contains(89));The following is an example to check if a particular element exists in HashSet −Example Live Demoimport java.util.*; public class Demo { public static void main(String args[]) { // create hash set Set hs = new HashSet(); hs.add(30); hs.add(67); ... Read More

The synchronizedSet() method returns a synchronized (thread-safe) sorted set backed by the specified sorted set.First, create a HashSet and add elements −Set hs = new HashSet(); hs.add(29); hs.add(879); hs.add(88); hs.add(788); hs.add(456);Now, to get synchronized set, use the synchronizedSet() method −Set s = Collections.synchronizedSet(hs);The following is an example to get synchronized set from HashSet −Example Live Demoimport java.util.*; public class Demo { public static void main(String args[]) { Set hs = new HashSet(); hs.add(29); hs.add(879); ... Read More

To get enumeration over HashSet, first declare the HashSet and add elements −HashSet hs = new HashSet(); hs.add("P"); hs.add("Q"); hs.add("R");To get enumeration −Enumeration e = Collections.enumeration(hs);The following is an example to get Enumeration over HashSet −Example Live Demoimport java.util.*; public class Demo {    public static void main(String[] args) {       HashSet hs = new HashSet();       hs.add("P");       hs.add("Q");       hs.add("R");       Enumeration e = Collections.enumeration(hs);       while (e.hasMoreElements())       System.out.println(e.nextElement()); } }OutputP Q R

To get the minimum element of HashSet, use the Collections.min() method.Declare the HashSet −Set hs = new HashSet();Now let us add the elements −hs.add(29); hs.add(879); hs.add(88); hs.add(788); hs.add(456);Let us now get the minimum element −Object obj = Collections.min(hs);The following is an example to find the minimum element of HashSet −Example Live Demoimport java.util.*; public class Demo { public static void main(String args[]) { // create hash set Set hs = new HashSet(); hs.add(29); hs.add(879); ... Read More