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In Java regex matches() matches the input string against the whole string as it add a ^ and $ at the end of the input string.so it will not match the substring. So for matching substring, you should use find().Exampleimport java.util.regex.*; class PatternMatchingExample { public static void main(String args[]) { String content = "aabbcc"; String string = "aa"; Pattern p = Pattern.compile(string); Matcher m = p.matcher(content); System.out.println(" 'aa' Match:"+ m.matches()); System.out.println(" 'aa' Match:"+ m.find()); } }Output'aa' Match:false 'aa' Match:true
A final variable can be explicitly initialized only once. A reference variable declared final can never be reassigned to refer to a different object.However, the data within the object can be changed. So, the state of the object can be changed but not the reference. As an array is also an object and it is referred by a reference variable which if set as final then cannot be reassigned. Let's see the examples for further explanation.Examplepublic class Tester { public static void main(String []args) { final int[] arr = {1, 2, 3}; ... Read More
With Java 9, new factory methods are added to List interface to create immutable instances. These factory methods are convenience factory methods to create a collection in less verbose and in concise way.Old way to create collectionsExampleimport java.util.ArrayList; import java.util.Collections; import java.util.List; public class Tester { public static void main(String []args) { List list = new ArrayList(); list.add("A"); list.add("B"); list.add("C"); List readOnlylist = Collections.unmodifiableList(list); System.out.println(readOnlylist); try { readOnlylist.remove(0); ... Read More
Dictionary is a collection of keys and values in C#. Dictionary is included in the System.Collection.Generics namespace.To create a dictionary, you first need to set it and add the key and values. Here we have added 5 keys with values to a Dictionary. We have set its keys and value type as int.IDictionary d = new Dictionary(); d.Add(1, 44); d.Add(2, 34); d.Add(3, 66); d.Add(4, 47); d.Add(5, 76);The following is the complete code −Exampleusing System; using System.Collections.Generic; public class Demo { public static void Main() { IDictionary d = new Dictionary(); d.Add(1, 44); ... Read More
Value Type and Reference, both are types in C# −Value TypeValue type variables can be assigned a value directly. They are derived from the class System.ValueType. The value types directly contain data. When you declare an int type, the system allocates memory to store the value.Value Type variables are stored in the stack.Examples are int, char, and float, which stores numbers, alphabets, and floating point numbers, respectively.Reference TypeIt refers to a memory location. Using multiple variables, the reference types can refer to a memory location. If the data in the memory location is changed by one of the variables, the ... Read More
With Java 9, new factory methods are added to Map interface to create immutable instances. These factory methods are convenience factory methods to create a collection in less verbose and in concise way.Old way to create collectionsExampleimport java.util.Collections; import java.util.HashMap; import java.util.Map; public class Tester { public static void main(String []args) { Map map = new HashMap(); map.put("A", "Apple"); map.put("B", "Boy"); map.put("C", "Cat"); Map readOnlyMap = Collections.unmodifiableMap(map); System.out.println(readOnlyMap); try { readOnlyMap.remove(0); ... Read More
To create, move and delete directories in C#, the System.IO.Directory class has methods.Firstly, import the System.IO namespace.Now, use the Director.CreateDirectory() method to create a directory in the specified path −string myDir = @"D:\NEW"; if (!Directory.Exists(myDir)) { Directory.CreateDirectory(myDir); }In the same way, you can create a sub-directory −string mysubdir = @"C:\NEW\my\"; Directory.CreateDirectory(mysubdir);
Use the param keyword to get the variable arguments in C#.Let us see an example to multiply integers. We have used params keyword to accept any number of int values −static int Multiply(params int[] b)The above allows us to find multiplication of numbers with one as well as two int values. The fllowing calls the same function with multiple values −int mulVal1 = Multiply(5); int mulVal2 = Multiply(5, 10);Let us see the complete code to understand how variable arguments work in C# −Exampleusing System; class Program { static void Main() { int mulVal1 = Multiply(5); ... Read More
With Java 9, new factory methods are added to Set interface to create immutable instances. These factory methods are convenience factory methods to create a collection in less verbose and in concise way.Old way to create collectionsExampleimport java.util.Collections; import java.util.HashSet; import java.util.Set; public class Tester { public static void main(String []args) { Set set = new HashSet(); set.add("A"); set.add("B"); set.add("C"); Set readOnlySet = Collections.unmodifiableSet(set); System.out.println(readOnlySet); try { readOnlySet.remove(0); ... Read More
Character literals are enclosed in single quotes. For example, 'x' and can be stored in a simple variable of char type. A character literal can be a plain character (such as 'x'), an escape sequence (such as '\t'), or a universal character (such as '\u02C0').Let us see an example how to define a character constant in C# −using System; namespace Demo { class Program { static void Main(string[] args) { Console.WriteLine("Welcome!\t"); Console.WriteLine("This is it!"); Console.ReadLine(); } } }Above, we ... Read More