Article Categories
- All Categories
-
Data Structure
-
Networking
-
RDBMS
-
Operating System
-
Java
-
MS Excel
-
iOS
-
HTML
-
CSS
-
Android
-
Python
-
C Programming
-
C++
-
C#
-
MongoDB
-
MySQL
-
Javascript
-
PHP
-
Economics & Finance
Programming Articles
Page 2328 of 2547
Difference between the byte stream and character stream classes in Java?
Java provides I/O Streams to read and write data where, a Stream represents an input source or an output destination which could be a file, i/o devise, other program etc.Based on the data they handle there are two types of streams −Byte Streams − These handle data in bytes (8 bits) i.e., the byte stream classes read/write data of 8 bits. Using these you can store characters, videos, audios, images etc.Character Streams − These handle data in 16 bit Unicode. Using these you can read and write text data only.The Reader and Writer classes (abstract) are the super classes of ...
Read MoreWrite a program to print message without using println() method in java?
The println() method of the System class accepts aStringas parameter an prints the given String on the console.Examplepublic class PrintData { public static void main(String args[]) { System.out.println("Hello how are you"); } }OutputHello how are youIn addition to this you can print data on the console in several other ways, some of them are −Using Output StreamsUsing output stream classes, you can write dat on the specified destination. You can print data on the screen/console by passing the standard output Stream object System.out as source to them.Exampleimport java.io.IOException; import java.io.OutputStreamWriter; public class PrintData { ...
Read MoreIs it possible to synchronize the string type in Java?
A thread is a piece of code (under execution) in a program, which executes a sub task of the process independently. independent process.In other words, a thread is a light weight process which executes a piece of code independently.Thread synchronizationIf a process has multiple threads running independently at the same time (multi-threading) and if all of them trying to access a same resource an issue occurs.To resolve this, Java provides synchronized blocks/ synchronized methods. If you define a resource (variable/object/array) inside a synchronized block or a synchronized method, if one thread is using/accessing it, other threads are not allowed to ...
Read MoreWhy String class is popular key in a HashMap in Java?
A map is a collection in Java which stores key value pairs. The keys of this must not be null and each key should point to only one value. It is represented by the Map interface of java.util package. There are various classes which provides implementation to this interface.The HashMap is a class which implements the Map interface. It is based on the Hash table. It allows null values and null keys.In short, you can store key value pairs in the HashMap object. Once you do so you can retrieve the values of the respective keys but, the values we ...
Read MoreHow to convert String to StringBuilder and vice versa Java?
The String type is a class in Java, it is used to represent a set of characters. Strings in Java are immutable, you cannot change the value of a String once created.Since a String is immutable, if you try to reassign the value of a String. The reference of it will be pointed to the new String object leaving an unused String in the memory.Java provides StringBuffer class as a replacement of Strings in places where there is a necessity to make a lot of modifications to Strings of characters.You can modify/manipulate the contents of a StringBuffer over and over again ...
Read MoreDefault method vs static method in an interface in Java?
An interface in Java is similar to class but, it contains only abstract methods and fields which are final and static.Since Java8 static methods and default methods are introduced in interfaces.Default Methods - Unlike other abstract methods these are the methods can have a default implementation. If you have default method in an interface, it is not mandatory to override (provide body) it in the classes that are already implementing this interface.In short, you can access the default methods of an interface using the objects of the implementing classes.Exampleinterface MyInterface{ public static int num = 100; public default void ...
Read MoreWhat is the reason behind the error "Could not found or load main class" in java?
When write a Java program/class first of all you need to compile it using the javac command as −javac [name of the class].javaIf your program gets compiled without errors, a .class file (byte code) is created with the specified name. Then you need to execute it using the java command (JVM) as −java [class name]ExampleSuppose we Have created a simple class Calculator which adds two or, three numbers in the file with name Calculator.java in the path D:\sample as −public class Calculator { int addition(int a , int b){ int result = a+b; ...
Read MoreCan super class reference variable hold sub class's object in java?
Yes, the super class reference variable can hold the sub class object actually, it is widening in case of objects (Conversion of lower datatype to a higher datatype).But, using this reference you can access the members of super class only, if you try to access the sub class members a compile time error will be generated.ExampleIn the following Java example, we have two classes namely Person and Student. The Person class has two instance variables name and age and one instance method displayPerson() which displays the name and age.The Student extends the person class and in addition to the inherited ...
Read MoreHow do you prevent a method from getting overridden in java?
Inheritance can be defined as the process where one (parent/super) class acquires the members (methods and fields) of another (child/sub).If two classes are related to each other with inheritance. If the super class and sub class contains same methods (same name and arguments), When we invoke this it using the sub class object, the method of the sub class will be executed. This mechanism is known as overriding.Overriding final methodsOnce you declare a method final it cannot be overridden If you try to do so, it generates a compile time error −Exampleclass Super{ public final void demo() { ...
Read MoreCan we call a constructor directly from a method in java?
A constructor 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 same name as their class and, have no return type.There is no need to invoke constructors explicitly these are automatically invoked at the time of instantiation.The this keyword in Java is a reference to the object of the current class. Using it, you can refer a field, method or, constructor of a class.Therefore, if you need to invoke a constructor explicitly you can do so, using "this()".Invoking a ...
Read More