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Object Oriented Programming Articles
Page 583 of 589
How to convert a byte array to a hex string in Java?
The printHexBinary() method of the DatatypeConverter class accepts a byte array and returns a hex string.Exampleimport javax.xml.bind.DatatypeConverter; public class ByteToHexString { public static void main(String args[]) { String sam = "Hello how are you how do you do"; byte[] byteArray = sam.getBytes(); String hex = DatatypeConverter.printHexBinary(byteArray); System.out.println(hex); } }Output48656C6C6F20686F772061726520796F7520686F7720646F20796F7520646F
Read MoreHow to declare a class in Java?
Following is the syntax to declare a class. class className { //Body of the class } You can declare a class by writing the name of the next to the class keyword, followed by the flower braces. Within these, you need to define the body (contents) of the class i.e. fields and methods.To make the class accessible to all (classes) you need to make it public. public class MyClass { //contents of the class (fields and methods) }
Read MoreWhy do Java array declarations use curly brackets?
Curly brackets usually denote sets and ensembles while parenthesis usually in most Algol-based programming languages curly braces are used to declare arrays.
Read MoreWhy are classes sometimes declared final in Java?
If a class is declared final, you cannot inherit it. If you try it gives you a compile-time error as − Example final class Super { private int data = 30; } public class Sub extends Sub { public static void main(String args[]){ } } Output Exception in thread "main" java.lang.Error: Unresolved compilation problem: at Sub.main(Sub.java:7)
Read MoreWhat is a composition in Java?
The composition is also a type of aggregation where the relationship is restrictive i.e. If two objects are in composition, the composed object will not exist without the other.
Read MoreWhat is the difference between compositions and aggregations in Java?
In Aggregation relationship among classes by which a class (object) can be made up of any combination of objects of other classes. It allows objects to be placed directly within the body of other classes.A composition is also a type of aggregation where the relationship is restrictive i.e. If two objects are in composition, the composed object will not exist without the other.
Read MoreWhat are native methods in Java and where are they used?
A native method in Java is a method whose implementation is written in other languages such as c and c++. The ‘native’ keyword is used before a method to indicate that it is implemented in other language.
Read MoreWhat is a method in Java that ends in a semicolon and has no method body?
An abstract method is the one which has no definition and declared abstract. In short, an abstract method contains only method signature without body. To use this method, you need to inherit this method by extending the class and provide the method definition. Example public abstract class Employee{ private String name; private String address; private int number; public abstract double computePay(); }
Read MoreWhat is Callable interface in Java?
The Callable interface is found in the package java.util.concurrent. The Callable object can return the computed result done by a thread in contrast to a runnable interface which can only run the thread. The Callable object returns a Future object which provides methods to monitor the progress of a task being executed by a thread. The future object can be used to check the status of a Callable and then retrieve the result from the Callable once the thread is done. It also provides timeout functionality.
Read MoreWhat is the difference between Component class and Container class in Java?
The class Component is the abstract base class for the non-menu user-interface controls of AWT. A component represents an object with graphical representation. The class Container is the superclass for the containers of AWT. The container object can contain other AWT components.
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