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Articles on Trending Technologies
Technical articles with clear explanations and examples
Calling virtual functions inside constructors in C++
Virtual functions calling from a constructor or destructor is dangerous and should be avoided whenever possible as the virtual function we call is called from the Base class and not from the derived class.The reason is that in C++ Super-classes are constructed before derived classes. So, in the following example, as B must be instantiated, before D is instantiated. When B's constructor is called, it's not D yet, so the virtual function table still has the entry for B's copy of s().Example Code#include using namespace std; class B { public: B() { s(); } virtual void s() { cout
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 MoreStringJoiner setEmptyValue() method in Java 8
The setEmptyValue() method of the StringJoiner class in Java 8 sets the sequence of characters. These characters are to be used when determining the string representation of this StringJoiner and when it is empty. That would be none of the elements have been added.The syntax is as followspublic StringJoiner setEmptyValue(CharSequence emptyVal)Here, emptyVal are the characters to return as the value of an empty StringJoinerTo work with the StringJoiner in Java 8, import the following package.import java.util.StringJoiner;The following is an example to implement StringJoiner setEmptyValue() method in Java:Exampleimport java.util.StringJoiner; public class Demo { public static void main(String[] args) { ...
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 MoreWhat is AbstractCollection class in Java?
The AbstractCollection class provides an implementation of the Collection interface. This is done to minimize the effort in the implementation of this interface.For an unmodifiable collectionExtend this class and provide implementations for the iterator and size methods.For modifiable collectionAdditionally override the add() method of the class. The iterator method returns the iterator and it must implement the remove() method.The syntax is as follows.public abstract class AbstractCollection extends Object implements CollectionHere, Object is the root of the class hierarchy and Collection is a group of objects.To work with AbstractCollection class in Java, import the following package.import java.util.AbstractCollection;Let us now see an ...
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 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 MoreFix for java.math.BigInteger cannot be cast to java.lang.Integer?
You can typecast with the help of method intValue(). The syntax is as follows −Integer yourVariableName=((BigInteger) yourBigIntegerValue).intValue();Here is the Java code to convert java.math.BigInteger cast to java.lang.Integer. The code is as follows −Exampleimport java.math.BigInteger; public class BigIntegerToInteger { public static void main(String []args) { BigInteger bigValue [] = new BigInteger[5]; bigValue[0] = new BigInteger("6464764"); bigValue[1] = new BigInteger("212112221122"); bigValue[2] = new BigInteger("76475"); bigValue[3] = new BigInteger("94874747"); bigValue[4] = new BigInteger("2635474"); for(int i = 0; i< bigValue.length; i++) { ...
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 MoreJava Programs for printing Pyramid Patterns. (of numbers)
Following is a Java program which prints a pyramid of numbers.Examplepublic class PrintingPyramids { public static void main(String args[]){ int n,i,j,k=1; n = 5; for(i = 0; i
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