Wan import statement in Java is used to − Import user defined classes/Interfaces Whenever you need to access a class which is not in the current package of the program you need to import that particular class using the import statement. Example In the following example we are using the Math class to find the square root of a number therefore, first of all w should import this class using the import statement. Live Demo import java.lang.Math.*; public class Sample{ public static void main(String args[]){ System.out.println(Math.sqrt(169)); ... Read More

As import statement allows to use a class without its package qualification, static import allows to access the static members of a class without class qualifications. For Example, to access the static methods you need to call the using class name − Math.sqrt(169); But, using static import you can access the static methods directly. Example Live Demo import static java.lang.Math.*; public class Sample{ public static void main(String args[]){ System.out.println(sqrt(169)); } } Output 13.0

No, java.lang package is a default package in Java therefore, there is no need to import it explicitly. i.e. without importing you can access the classes of this package. If you observe the following example here we haven’t imported the lang package explicitly but, still we are able to calculate the square root of a number using the sqrt() method of the java.lang.Math class. Example Live Demo public class LangTest { public static void main(String args[]){ int num = 100; double result = ... Read More

As per dictionary, abstraction is the quality of dealing with ideas rather than events. For example, when you consider the case of e-mail, complex details such as what happens as soon as you send an e-mail, the protocol your e-mail server uses are hidden from the user. Therefore, to send an e-mail you just need to type the content, mention the address of the receiver, and click send. Abstraction is a process of hiding the implementation details from the user, only the functionality will be provided to the user. In other words, the user will have the information on what ... Read More

Passing Parameters by Value means calling a method with a parameter. Through this, the argument value is passed to the parameter. Example public class SwappingExample { public static void swapFunction(int a, int b) { int c = a+b; System.out.println("Sum of the given numbers is ::"+c); } public static void main(String[] args) { int a = 30; int b = 45; swapFunction(a, b); } } Output Sum of the given numbers is ::75

Recursion is where which a method class itself.Examplepublic class RecursionExample {    private static long factorial(int n) {    if (n == 1)       return 1;    else       return n * factorial(n-1);    }    public static void main(String args[]) {       RecursionExample obj = new RecursionExample();       long result = obj.factorial(5);       System.out.println(result);    } }

On a multiuser operating system, a home directory is a file system location that holds the files specific to a particular user. A login directory is another name for a home directory.You may obtain the home directory using Python in a number of ways. Using os module The os.path.expanduser() function in Python provides the most straightforward method for retrieving the user home directory across all platforms. The Python os module offers os.path.expanduser(") to retrieve the home directory. This also functions if it is a part of a longer path. The function will return the path unchanged if there is no ... Read More

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

To touch all the  files recursively, you need to walk the directory tree using os.walk and add touch all the files in it using os.utime(path_to_file). exampleimport os # Recursively walk the tree for root, dirs, files in os.walk(path):     for file in files:         # Set utime to current time         os.utime(os.path.join(root, file))In Python 3.4+, you can directly use the pathlib module to touch files.  examplefrom pathlib import Path import os # Recursively walk the tree for root, dirs, files in os.walk(path):     for file in files:         Path(os.path.join(root, file)).touch()Read More