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Articles by Chandu yadav
Page 35 of 81
Count the Number of matching characters in a pair of Java string
In order to find the count of matching characters in two Java strings the approach is to first create character arrays of both the strings which make comparison simple.After this put each unique character into a Hash map.Compare each character of other string with created hash map whether it is present or not in case if present than put that character into other hash map this is to prevent duplicates.In last get the size of this new created target hash map which is equal to the count of number of matching characters in two given strings.Exampleimport java.util.HashMap; public class MatchingCharacters ...
Read MoreFind frequency of each word in a string in Java
In order to get frequency of each in a string in Java we will take help of hash map collection of Java.First convert string to a character array so that it become easy to access each character of string.Now compare for each character that whether it is present in hash map or not in case it is not present than simply add it to hash map as key and assign one as its value.And if character is present than find its value which is count of occurrence of this character in the string (initial we put as 1 when it ...
Read MoreHow to convert JS date time to MySQL datetime?
We can convert JS date time to MySQL datetime with the help of toISOString() function.Let us see an example of JavaScript.Example Web Page Design document.writeln(new Date().toISOString().slice(0, 19).replace('T', ' ')); Current Date is displayed above... OutputThe following is the output.2018-11-23 11:14:38 Current Date is displayed above...
Read MoreReplace All Elements Of ArrayList with with Java Collections
In order to replace all elements of ArrayList with Java Collections, we use the Collections.fill() method. The static void fill(List list, Object element) method replaces all elements in the list with the specified element in the argument.Declaration −The java.util.Collections.fill() method is declared as follows −public static void fill(List
Read MoreSwap elements of ArrayList with Java collections
In order to swap elements of ArrayList with Java collections, we need to use the Collections.swap() method. It swaps the elements at the specified positions in the list.Declaration −The java.util.Collections.swap() method is declared as follows −public static void swap(List list, int i, int j)where i is the index of the first element to be swapped, j is the index of the other element to be swapped and list is the list where the swapping takes place.Let us see a program to swap elements of ArrayList with Java collections −Exampleimport java.util.*; public class Example { public static void main ...
Read MoreHow to prevent Reflection to break a Singleton Class Pattern?
A Singleton pattern states that a class can have a single instance and multiple instances are not permitted to be created. For this purpose, we make the constructor of the class a private and return a instance via a static method. But using reflection, we can still create multiple instance of a class by modifying the constructor scope. See the example below −Example - Breaking Singletonimport java.io.Serializable; import java.lang.reflect.Constructor; import java.lang.reflect.InvocationTargetException; public class Tester { public static void main(String[] args) throws InstantiationException, IllegalAccessException, IllegalArgumentException, InvocationTargetException{ A a = A.getInstance(); ...
Read MoreDisplay the package name of a class in Java
The package for a class can be obtained using the java.lang.Class.getPackage() method with the help of the class loader of the class. If there is no package object created by the class loader of the class, then null is returned.A program that demonstrates this is given as follows −Exampleimport java.util.Date; public class Main { public static void main(String[] args) { Date d = new Date(); Package p = d.getClass().getPackage(); String pName = p.getName(); System.out.println("The package name is: " + pName); } }OutputThe package name is: java.utilNow ...
Read MoreImplement Runnable vs Extend Thread in Java
We can create Thread by either by implementing a runnable interface or by extending Thread class. Below are the detailed steps of using both ways to create Thread.Create a Thread by Implementing a Runnable InterfaceIf your class is intended to be executed as a thread then you can achieve this by implementing a Runnable interface. You will need to follow three basic steps −Step 1As a first step, you need to implement a run() method provided by a Runnable interface. This method provides an entry point for the thread and you will put your complete business logic inside this method. ...
Read Moreinstanceof operator vs isInstance method in java
isInstance method is equivalent to instanceof operator. The method is used in case of objects are created at runtime using reflection. General practice says if type is to be checked at runtime then use isInstance method otherwise instanceof operator can be used. See the example below −Examplepublic class Tester{ public static void main(String[] args) throws ClassNotFoundException { Integer i = new Integer(10); System.out.println(usingInstanceOf(i)); System.out.println(usingIsInstance(i)); } public static String usingInstanceOf(Object i){ if(i instanceof String){ return "String"; } ...
Read MoreJagged Array in Java
Jagged array is a multidimensional array where member arrays are of different size. For example, we can create a 2D array where first array is of 3 elements, and is of 4 elements. Following is the example demonstrating the concept of jagged array.Examplepublic class Tester { public static void main(String[] args){ int[][] twoDimenArray = new int[2][]; //first row has 3 columns twoDimenArray[0] = new int[3]; //second row has 4 columns twoDimenArray[1] = new int[4]; int counter = 0; ...
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