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Java Articles
Page 35 of 450
Retrieve 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)); ...
Read MoreGet the count of elements in HashMap in Java
Use the size() method to get the count of elements.Let us first create a HashMap and add elements −HashMap hm = new HashMap(); // Put elements to the map hm.put("Maths", new Integer(98)); hm.put("Science", new Integer(90)); hm.put("English", new Integer(97));Now, get the size −hm.size()The following is an example to get the count of HashMap elements −Exampleimport java.util.*; public class Demo { public static void main(String args[]) { // Create a hash map HashMap hm = new HashMap(); // Put elements to ...
Read MoreDisplay HashMap elements in Java
Create a HashMap −HashMap hm = new HashMap();Add elements to the HashMap that we will be displaying afterward −hm.put("Maths", new Integer(98)); hm.put("Science", new Integer(90)); hm.put("English", new Integer(97)); hm.put("Physics", new Integer(91));Now, to display the HashMap elements, use Iterator. The following is an example to display HashMap elements −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 ...
Read MoreFind the size of a HashMap in Java
Use the size() method to get the size of HashMap. Let us first create a HashMapHashMap hm = new HashMap();Now, add some elements −hm.put("Bag", new Integer(1100)); hm.put("Sunglasses", new Integer(2000)); hm.put("Franes", new Integer(800)); hm.put("Wallet", new Integer(700)); hm.put("Belt", new Integer(600));Since, we added 5 elements above, therefore, the size() method will give 5 as the result −set.size()The following is an example to find the size of HashMap −Exampleimport java.util.*; public class Demo { public static void main(String args[]) { // Create a hash map HashMap hm = new ...
Read MoreConvert elements in a HashSet to an array in Java
First, create a HashSet and elements to it −HashSet hs = new HashSet(); // add elements to the hash set hs.add("B"); hs.add("A"); hs.add("D"); hs.add("E"); hs.add("C"); hs.add("F"); hs.add("K");Let us now convert the above HashSet to an array −Object[] ob = hs.toArray();The following is an example to convert elements in a HashSet to an array −Exampleimport java.util.*; public class Demo { public static void main(String args[]) { // create a hash set HashSet hs = new HashSet(); // add elements to ...
Read MoreCheck whether two HashSet are equal in Java
At first, create the first HashSet and add elements to it −// create hash set 1 HashSet hs1 = new HashSet(); hs1.add("G"); hs1.add("H"); hs1.add("I"); hs1.add("J"); hs1.add("K");Create the second HashSet and add elements to it −// create hash set 2 HashSet hs2 = new HashSet(); hs2.add("G"); hs2.add("H"); hs2.add("I"); hs2.add("J"); hs2.add("K");To check whether both the HashSet are equal or not, use the equals() method −hs1.equals(hs2)The following is an example to check whether two HashSet are equal −Exampleimport java.util.*; public class Demo { public static void main(String args[]) { // create hash set 1 ...
Read MoreFind maximum element of HashSet in Java
To get the maximum element of HashSet, use the Collections.max() 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 maximum element −Object obj = Collections.max(hs);The following is an example to find maximum element of HashSet −Exampleimport 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 MoreAdding elements in the middle of an ArrayList in Java
Elements can be added in the middle of an ArrayList by using the java.util.ArrayList.add() method. This method has two parameters i.e. the index at which to insert the element in the ArrayList and the element itself. If there is an element already present at the index specified by ArrayList.add() then that element and all subsequent elements shift to the right by one.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[]) throws Exception { List aList = new ArrayList(); ...
Read MoreGet the count of NavigableMap in Java
To get the count of NavigableMap in Java, use the size() method.Let us first create NavigableMap and add elements −NavigableMap n = new TreeMap(); n.put(5, "Tom"); n.put(9, "John"); n.put(14, "Jamie"); n.put(1, "Tim"); n.put(4, "Jackie");Now, get the count −n.size()The following is an example to implement the size() method to get the count of the NavigableMap elements −Exampleimport java.util.*; public class Demo { public static void main(String[] args) { NavigableMap n = new TreeMap(); n.put(5, "Tom"); n.put(9, "John"); ...
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