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In Java final is the access modifier which can be used with a filed class and a method.When a method if final it cannot be overridden.When a variable is final its value cannot be modified further.When a class is finale it cannot be extended.Declaring final variable without initializationIf you declare a variable as final, it is mandatory to initialize it before the end of the constructor. If you don’t you will get a compilation error.ExampleIn the following java program, we a have an interface with a public, static, final variable with name num and, a public, abstract method with name ... Read More
No, you cannot instantiate an interface. Generally, it contains abstract methods (except default and static methods introduced in Java8), which are incomplete.Still if you try to instantiate an interface, a compile time error will be generated saying “MyInterface is abstract; cannot be instantiated”.In the following example we an interface with name MyInterface and a class with name InterfaceExample.In the interface we have an integer filed (public, static and, final) num and abstract method demo().From the class we are trying to − create an object of the interface and print the num value.Example Live Demointerface MyInterface{ public static final int num ... Read More
The default methods in an interface in Java are also known as defender methods or, virtual methods.The defender/virtual methods are those that will have a default implementation in an interface. You can define defender/virtual methods using the default keyword as −default void display() { System.out.println("This is a default method"); }There is no need to implement these defender/virtual methods in the implementing classes you can call them directly.If you have an interface which is implemented by some classes and if you want to add a new method int it.Then, you need to implement this newly added method in all the ... Read More
An interface in Java is similar to class but, it contains only abstract methods and fields which are final and static.A static method is declared using the static keyword and it will be loaded into the memory along with the class. You can access static methods using class name without instantiation.Static methods in an interface since java8Since Java8 you can have static methods in an interface (with body). You need to call them using the name of the interface, just like static methods of a class.ExampleIn the following example, we are defining a static method in an interface and accessing ... Read More
Interface in Java is similar to class but, it contains only abstract methods and fields which are final and static.Since all the methods are abstract you cannot instantiate it. To use it, you need to implement this interface using a class and provide body to all the abstract methods int it.Non static variables in an interfaceNo you cannot have non-static variables in an interface. By default, All the members (methods and fields) of an interface are publicAll the methods in an interface are public and abstract (except static and default).All the fields of an interface are public, static and, final ... Read More
Java provides supporting classes/datatypes to store all the MySQL datatypes, following is the table which list outs the respective java types for MySQL datatypes −MySQL TypeJava TypeCHARStringVARCHARStringLONGVARCHARStringNUMERICjava.math.BigDecimalDECIMALjava.math.BigDecimalBITbooleanTINYINTbyteSMALLINTshortINTEGERintBIGINTlongREALfloatFLOATdoubleDOUBLEdoubleBINARYbyte []VARBINARYbyte []LONGVARBINARYbyte []DATEjava.sql.DateTIMEjava.sql.TimeTIMESTAMPjava.sql.TiimestampExampleFollowing JDBC program creates a table with name sample with all the possible datatypes in MySQL −import java.sql.Connection; import java.sql.DriverManager; import java.sql.Statement; public class CreatingTable_AllDatatypes { public static void main(String args[])throws Exception { //Registering the Driver DriverManager.registerDriver(new com.mysql.jdbc.Driver()); //Getting the connection String mysqlUrl = "jdbc:mysql://localhost/sampledatabase"; Connection con = DriverManager.getConnection(mysqlUrl, "root", "password"); System.out.println("Connection ... Read More
To download a video from a URL in swift we need to perform a few steps while keeping a few things in mind.Points to be noted here are, We’ll be making use of internet to download video, hence we need to allow permissions for App transport security in our Info.plistWe’ll need to save the downloaded video to Photos app, hence photos permission is required.Video should always be downloaded in background as it may prevent us from using the app if downloaded on foreground.Now, we’ll use the below code to save a video from a random link in our Device. You’ll ... Read More
To replace a character in objective C we will have to use the inbuilt function of Objective C string library, which replaces occurrence of a string with some other string that we want to replace it with.To create a string in objective C we need to write −NSString *str = @"tutori@als";Now we have a choice of replacing characters in this string and creating new one, or modify this same string. In this example we will modify this string and print in the next line.str = [str stringByReplacingOccurrencesOfString:@"@" withString:@""]; NSLog(@”%@”, str);When we run the above code, str is replaced with “tutorials” ... Read More
To change the background color of a button in iOS application we need to access the property ‘ backgroundColor’ of the UIButton. We can do this in two ways, programmatically and using the storyboard.Method 1 − Using the storyboard editorAdd a button on your storyboard, select it Go to it’s attribute inspector and select 'Background' property to choose the color.Method 2 − Programmatically changing the backgroundCreate outlet of the button on the View Controller.In the viewDidLoad() or viewWillLayoutSubview() method add the code to change the background color.btn.backgroundColor = #colorLiteral(red: 0.4392156899, green: 0.01176470611, blue: 0.1921568662, alpha: 1)When we run the method ... Read More
Importing all methods from a module in Python is a bad idea because of the following reasons.It is difficult to find a parent module of the method which we used in the programs.We are not allowed to create our functions with the names of methods.Let's see an example. Below we write a function called add in the sample.py.## sample.py file def add(a, b): return a + bExampleSave the above file in the same directory as below Python file.## let's assume we have module called sample from sample import * def add(*nums): return sum(nums) print(add(1, 2, 3, 4, ... Read More