Programming Articles - Page 3312 of 3366

Converting a subclass type to a superclass type is known as up-casting.Converting a superclass type to a subclass type is known as down-casting.

Typecasting is converting one data type to another.Up-casting − Converting a subclass type to a superclass type is known as up casting.Exampleclass Super {    void Sample() {       System.out.println("method of super class");    } } public class Sub extends Super {    void Sample() {       System.out.println("method of sub class");    }        public static void main(String args[]) {       Super obj =(Super) new Sub(); obj.Sample();    } }Down-casting − Converting a superclass type to a subclass type is known as downcasting.Exampleclass Super {    void Sample() {     ... Read More

In file system management, it's sometimes necessary to update the modification or access time of files which is commonly referred as "touching" files. This is useful in automation scripts, build systems or cache invalidation mechanisms. Python offers powerful modules such as os and pathlib to touch all files within a directory recursively. In this article, we'll explore different methods to recursively touch files using Python by ensuring each file's timestamp is refreshed as needed. Using os.walk() and os.utime() The os.walk() function generates the file names in a directory tree by walking the tree either top-down approach or bottom-up approach. It ... Read More

Multiple inheritances lead to ambiguity.For example, if there is a class named Sub and there are two classes Super1 and Super2 and if both contains a method named sample(). And if the class sub inherits both classes Super1 and Super2 then there will be two copies of the sampling method one from each superclass and it is ambiguous to decide which method to be executed.

Zipping a folder recursively means compressing a folder along with all its subfolders and files. In this article, we will explore all the possible ways to zip a folder recursively using Python. Using zipfile and os.walk() In Python, we have the methods zipfile() and os.walk() to zip all the folders recursively. This is a manual approach of zipping the available subfolders and files into one. Following is an example that shows how to zip a folder recursively using Python - import zipfile import os def zip_folder_manual(folder_path, zip_path): with zipfile.ZipFile(zip_path, 'w', zipfile.ZIP_DEFLATED) as zipf: ... Read More

Association of method call with the method body is known as binding in Java. There are two kinds of binding. Static binding In static binding the method call is bonded with the method body at compile time. This is also known as early binding. This is done using static, private and, final methods. Example class Super{ public static void sample(){ System.out.println("This is the method of super class"); } } Public class Sub extends Super{ Public static void sample(){ ... Read More

In Python, pip is a standard tool which is used to install third-party packages in our system. By default, pip installs packages into the site-packages directory of the current Python environment but in some cases, such as restricted environments or creating portable apps, we may need to install packages into a different directory. Then we can use the pip's --target option. Syntax Following is the syntax of using the pip command while installing a python package in a different directory - pip install --target The above command tells pip to install the specified package and all its ... Read More

You can create an object of the class named Class in two ways −Using new keyword as −Class obj = new Class();Using the forName() method of the class named Class.Class obj = Class.forName("DemoTest");

You can access the private methods of a class using java reflection package.Step1 − Instantiate the Method class of the java.lang.reflect package by passing the method name of the method which is declared private.Step2 − Set the method accessible by passing value true to the setAccessible() method.Step3 − Finally, invoke the method using the invoke() method.Exampleimport java.lang.reflect.Method; public class DemoTest {    private void sampleMethod() {       System.out.println("hello");    } } public class SampleTest {    public static void main(String args[]) throws Exception {       Class c = Class.forName("DemoTest");       Object obj = c.newInstance(); ... Read More

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(); }