Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
In general, data is stored in a computer in the form of bits (1 or, 0). There are various coding schemes available specifying the set of bytes represented by each character.Unicode (UTF) − Stands for Unicode Translation Format. It is developed by The Unicode Consortium. if you want to create documents that use characters from multiple character sets, you will be able to do so using the single Unicode character encodings. It provides 3 types of encodings.UTF-8 − It comes in 8-bit units (bytes), a character in UTF8 can be from 1 to 4 bytes long, making UTF8 variable width.UTF-16 ... Read More
You can verify whether a particular file exists in the system in two ways using the File class and using the Files class.Using The File classThe class named File of the java.io package represents a file or directory (path names) in the system. This class provides various methods to perform various operations on files/directories.This class provides various methods to manipulate files, The exists a () method of it verifies whether the file or directory represented by the current File object exists if so, it returns true else it returns false.ExampleThe following Java program verifies whether a specified file exists in ... Read More
The BufferedReader class of Java is used to read the stream of characters from the specified source (character-input stream). The constructor of this class accepts an InputStream object as a parameter.This class provides a method known as readLine() which reads and returns the next line from the source and returns it in String format.The BufferedReader class doesn’t provide any direct method to read an integer from the user you need to rely on the readLine() method to read integers too. i.e. Initially you need to read the integers in string format.The parseInt() method of the Integer class accepts a String ... Read More
When you declare the instance variables of a class private, you cannot access them in another class if you try to do so a compile-time error will be generated.But, if you inherit a class that has private fields, including all other members of the class the private variables are also inherited and available for the subclass.But, you cannot access them directly, if you do so a compile-time error will be generated.Example Live Democlass Person{ private String name; public Person(String name){ this.name = name; } public void displayPerson() { System.out.println("Data of the ... Read More
ConstructorsA constructor in Java is similar to method and it is invoked at the time creating an object of the class, it is generally used to initialize the instance variables of a class. The constructors have the same name as their class and, have no return type.If you do not provide a constructor the compiler defines one on your behalf, which initializes the instance variables with default values.You can also accept parameters through constructors and initialize the instance variables of a class using the given values, these are known as parameterized constructors.ExampleThe following Java program has a class named student ... Read More
When we have two classes where one extends another and if, these two classes have the same method including parameters and return type (say, sample) the method in the subclass overrides the method in the superclass.i.e. Since it is an inheritance. If we instantiate the subclass a copy of superclass’s members is created in the subclass object and, thus both methods are available to the object of the subclass.But if you call the method (sample), the sampling method of the subclass will be executed overriding the super class’s method.Example Live Democlass Super{ public static void sample(){ System.out.println("Method ... Read More
Converting one data type to others in Java is known as casting.If you convert a higher datatype to lower datatype, it is known as narrowing (assigning higher data type value to the lower data type variable).char ch = (char)5;If you convert a lower data type to a higher data type, it is known as widening (assigning lower data type value to the higher data type variable).Int i = 'c';Similarly, you can also cast/convert an object of one class type to others. But these two classes should be in an inheritance relation. Then, If you convert a Super class to subclass ... Read More
The clone() method belongs to the class named Object of the java.lang package, it accepts an object as a parameter creates and returns a copy of it.In order to use this method, you need to make sure that your class implements the Cloneable (marker) interface.Example Live Demopublic class CloneExample implements Cloneable { private String name; private int age; public CloneExample(String name, int age){ this.name = name; this.age = age; } public void displayData(){ System.out.println("Name : "+this.name); System.out.println("Age : "+this.age); } public static ... Read More
Once you implement an interface from a concrete class you need to provide implementation to all its methods. If you try to skip implementing methods of an interface at compile time an error would be generated.Example Live Demointerface MyInterface{ public void sample(); public void display(); } public class InterfaceExample implements MyInterface{ public void sample(){ System.out.println("Implementation of the sample method"); } public static void main(String args[]) { InterfaceExample obj = new InterfaceExample(); obj.sample(); } }Compile-time errorInterfaceExample.java:5: error: InterfaceExample is not abstract and does not override abstract method ... Read More
Polymorphism is the ability of an object to perform different actions (or, exhibit different behaviors) based on the context.Overloading is one of the mechanisms to achieve polymorphism where a class contains two methods with the same name and different parameters.Whenever you call this method the method body will be bound with the method call based on the parameters.ExampleIn the following Java program, the Calculator class has two methods with name addition the only difference is that one contains 3 parameters and the other contains 2 parameters.Here, we can call the addition method by passing two integers or three integers. Based ... Read More