Java Articles - Page 145 of 440

All of these functions are used to get character from input and each function returns an integer signifying the status code as well.Following are the important differences between getc(), getchar(), getch() and getche() functions.getc()getc() can read characters from any stream. Returns EOF on failure.Syntaxint getc(FILE *stream);getchar()getchar() can read characters from standard input only.Syntaxint getchar();getch()getch() can read characters from standard input but it does not use any buffer and returns immidately without waiting for enter key pressed.Syntaxint getch();getche()getche() behaves similar to getch() as it can read characters from standard input and it does not use any buffer and returns immidately without ... Read More

Class A class is a blueprint from which individual objects are created. A class can contain any of the following variable types. Local Variables − Variables defined inside methods, constructors or blocks are called local variables. The variable will be declared and initialized within the method and the variable will be destroyed when the method has completed. Instance Variables − Instance variables are variables within a class but outside any method. These variables are initialized when the class is instantiated. Instance variables can be accessed from inside any method, constructor or blocks of that particular class. Class Variables − Class variables are variables declared ... Read More

Scanner and BufferedReader classes are used to read input from an external system. Scanner is normally used when we know input is of type string or of primitive types, and BufferedReader is used to read text from character streams while buffering the characters for efficient reading of characters. What is Scanner Class? The Scanner class is included in the java.util package. It is mostly used when the data type of the input is already known. We commonly use it with data ty+pes like strings, integers, floats, and booleans. It has built-in methods like nextInt(), nextDouble(), and nextLine() that help ... Read More

Abstract class and concrete class are fundamental concepts of object oriented programming in Java. In this article, we will learn the differences between an abstract class and concrete class. What is an Abstract Class? An abstract class is a class that cannot be used to create objects. It can only be accessed using its subclasses. It can contain abstract methods, which are methods without a body. It acts as a blueprint for its subclasses. It can also contain concrete or regular methods. Example This example shows how to implement an abstract class in java: ... Read More

The compile method of the patter class accepts two parameters −A string value representing the regular expression.An integer value a field of the Pattern class.This CASE_INSENSITIVE field of the Pattern class matches characters irrespective of case. Therefore, if you pass as flag value to the compile() method along with your regular expression, characters of both cases will be matched.Example 1import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example {    public static void main( String args[] ) {       Scanner sc = new Scanner(System.in);       System.out.println("Enter input data: ");       String input = sc.nextLine(); ... Read More

You can match numbers in the given string using either of the following regular expressions −“\d+” Or, "([0-9]+)"Example 1import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class ExtractingDigits {    public static void main(String[] args) {       Scanner sc = new Scanner(System.in);       System.out.println("Enter sample text: ");       String data = sc.nextLine();       //Regular expression to match digits in a string       String regex = "\d+";       //Creating a pattern object       Pattern pattern = Pattern.compile(regex);       //Creating a Matcher object       Matcher ... Read More

The metacharacter “\s” matches spaces and + indicates the occurrence of the spaces one or more times, therefore, the regular expression \S+ matches all the space characters (single or multiple). Therefore, to replace multiple spaces with a single space.Match the input string with the above regular expression and replace the results with single space “ ”.Example 1import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class ReplaceAllExample {    public static void main(String args[]) {       //Reading String from user       System.out.println("Enter a String");       Scanner sc = new Scanner(System.in);       String input = ... Read More

The regular expression “[a-zA-Z]+” matches one or the English alphabet. Therefore, to extract each word in the given input string −Compile the above expression of the compile() method of the Pattern class.Get the Matcher object bypassing the required input string as a parameter to the matcher() method of the Pattern class.Finally, for each match get the matched characters by invoking the group() method.Exampleimport java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class EachWordExample {    public static void main(String[] args) {       Scanner sc = new Scanner(System.in);       System.out.println("Enter sample text: ");       String data = ... Read More

You can match a valid mobile number using the following regular expression −"\d{10}"A valid mobile number generally have 10 digits (in India).The metacharacter "\d" matches the digits from 0 to 9.The quantifier ex{n} suggests the repetition of ex n times.Example 1import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class PhoneNumberExample {    public static void main(String[] args) {       Scanner sc = new Scanner(System.in);       System.out.println("Enter your name: ");       String name = sc.nextLine();       System.out.println("Enter your Phone number: ");       String phone = sc.next();       //Regular expression to ... Read More

Following is the regular expression to match alphabet in the given input −"^[a-zA-Z]*$"Where,^ matches the starting of the sentence.[a-zA-z] matches the lower case and upper case letters.* indicates the occurrence for zero or more times.& indicates the end of the line.Example 1import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class ContainsAlphabetExample {    public static void main(String[] args) {       Scanner sc = new Scanner(System.in);       String names[] = new String[5];       for(int i=0; i