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Programming Articles
Page 2329 of 2547
Sequence of execution of, instance method, static block and constructor in java?
A static block is a block of code with a static keyword. In general, these are used to initialize the static members of a class. JVM executes static blocks before the main method at the time loading a class.Examplepublic class MyClass { static{ System.out.println("Hello this is a static block"); } public static void main(String args[]){ System.out.println("This is main method"); } }OutputHello this is a static block This is main methodA constructor is similar to method and it is invoked at the time creating an object of the class, it is ...
Read MoreWhat is diamond problem in case of multiple inheritance in java?
Inheritance is a relation between two classes where one class inherits the properties of the other class. This relation can be defined using the extends keyword as −public class A extends B{ }The class which inherits the properties is known as sub class or, child class and the class whose properties are inherited is super class or, parent class.In inheritance a copy of super class members is created in the sub class object. Therefore, using the sub class object you can access the members of the both classes.Multiple inheritanceThere are various types of inheritance available namely single, multilevel, hierarchical, multiple ...
Read MoreHow to make an object completely encapsulated in java?
The process of wrapping up the data and, the code acting on the data together is known as encapsulation. This is a protective mechanism where we hide the data of one class from (an object of) another.Since, variables hold the data of a class to encapsulate a class you need to declare the required variables (that you want to hide) private and provide public methods to access (read/write) them.By doing so, you can access the variables only in the current class, they will be hidden from other classes, and can be accessed only through the provided methods. Therefore, it is ...
Read MoreDoes java support hybrid inheritance?
Inheritance is a relation between two classes where one class inherits the properties of the other class. This relation can be defined using the extends keyword as −public class A extends B{ }The class which inherits the properties is known as sub class or, child class and the class whose properties are inherited is super class or, parent class.In inheritance a copy of super class members are created in the sub class object. Therefore, using the sub class object you can access the members of the both classes.Exampleclass Super{ int a =100; int b = 200; public void ...
Read MoreImportance of SerialVersionUID keyword in Java?
SerialVersionUIDThe SerialVersionUID must be declared as a private static final long variable in Java. This number is calculated by the compiler based on the state of the class and the class attributes. This is the number that will help the JVM to identify the state of an object when it reads the state of the object from a file.The SerialVersionUID can be used during deserialization to verify that the sender and receiver of a serialized object have loaded classes for that object that are compatible w.r.t serialization. If the deserialization object is different than serialization, then it can throw an ...
Read MorePrint system time in C++ (3 different ways)
There are different ways by which system day, date and time can be printed in Human Readable Form.First wayUsing time() − It is used to find the current calendar time and have arithmetic data type that store timelocaltime() − It is used to fill the structure with date and timeasctime() − It converts Local time into Human Readable FormatDay Month Date hour:month:second YearExample#include #include // used to work with date and time using namespace std; int main() { time_t t; // t passed as argument in function time() struct tm * tt; // decalring variable for localtime() ...
Read MoreHow can we call the invokeLater() method in Java?
An invokeLater() method is a static method of the SwingUtilities class and it can be used to perform a task asynchronously in the AWT Event dispatcher thread. The SwingUtilities.invokeLater() method works like SwingUtilities.invokeAndWait() except that it puts the request on the event queue and returns immediately. An invokeLater() method does not wait for the block of code inside the Runnable referred by a target to execute.Syntaxpublic static void invokeLater(Runnable target)Exampleimport java.awt.*; import java.awt.event.*; import javax.swing.*; public class InvokeLaterTest extends Object { private static void print(String msg) { String name = Thread.currentThread().getName(); ...
Read MoreHow to implement a rollover effect for a JButton in Java?
A JButton is a subclass of AbstractButton and it can be used for adding platform-independent buttons to a GUI application. A JButon can generate an ActionListener interface when the button is pressed or clicked, it can also generate the MouseListener and KeyListener interfaces. We can implement the rollover effect when the mouse moves over a JButton by overriding the mouseEntered() method of the MouseListener interface.Syntaxvoid mouseEntered(MouseEvent e)Exampleimport java.awt.*; import java.awt.event.*; import javax.swing.*; public class RollOverButtonTest extends JFrame { private JButton button; public RollOverButtonTest() { setTitle("RollOverButton Test"); ...
Read MoreList Methods in Python - in, not in, len(), min(), max()
In this article, we will learn about various types of list methods available to us in Python 3.x. Or earlier. These operators allow us to perform the basic operations on the list content.In & Not in operators“in” operator − This operator is used to check whether an element is present in the passed list or not. Returns true if the element is present in the list otherwise returns false.“not in” operator − This operator is used to check whether an element is not present in the passed list or not. Returns true if the element is not present in the ...
Read MoreIterate over a dictionary in Python
In this article, we will learn about iteration/traversal of a dictionary in Python 3.x. Or earlier.A dictionary is an unordered sequence of key-value pairs. Indices can be of any immutable type and are called keys. This is also specified within curly braces.Method 1 − Using iterables directlyExampledict_inp = {'t':'u', 't':'o', 'r':'i', 'a':'l', 's':'p', 'o':'i', 'n':'t'} # Iterate over the string for value in dict_inp: print(value, end='')OutputtrasonMethod 2 − Using iterables for values of the dictionaryExampledict_inp = {'t':'u', 't':'o', 'r':'i', 'a':'l', 's':'p', 'o':'i', 'n':'t'} # Iterate over the string for value in dict_inp.values(): print(value, end='')OutputoilpitMethod 3 − ...
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