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Programming Articles
Page 2331 of 2547
Accessing variables of two interfaces, which are same from an implementing class in java?
An interface in Java is similar to class but, it contains only abstract methods and fields which are final and static.You can implement multiple interfaces using a single class in Java. Whenever both interfaces have same name, since all the fields of an interface are static by default, you can access them using the name of the interface as −Exampleinterface MyInterface1{ public static int num = 100; public void display(); } interface MyInterface2{ public static int num = 1000; public void show(); } public class InterfaceExample implements MyInterface1, MyInterface2{ public static int num = 10000; ...
Read MoreWhat happens if we does not initialize variables of an interface in java?
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 MoreCan we create non static variables in an interface using java?
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 MoreExample to create a table with all datatypes in MySQL using JDBC?
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 MoreHow to detect shake gesture using Swift?
To detect a shake gesture in iOS UIKit provides three different methods, let’s see them one by one.Method 1 − When the shake gesture begins.override func motionBegan(_ motion: UIEvent.EventSubtype, with event: UIEvent?) { // code you want to implement }Method 2 − When the shake gesture ends.override func motionEnded(_ motion: UIEvent.EventSubtype, with event: UIEvent?) { // Code you want to implement. }Method 3 − when the shake gesture is cancelled.override func motionCancelled(_ motion: UIEvent.EventSubtype, with event: UIEvent?) { // code you want to implement. }Now let’s add some code in our motionBegan method, override func motionBegan(_ motion: UIEvent.EventSubtype, with event: ...
Read MoreWhat happens if we define a concrete method in an interface in java?
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.Concrete methods in an interfaceAll the methods in an interface must be abstract, you cannot have a concrete method (the one which has body) if you try to do so, it gives you a compile time error saying “interface abstract methods cannot have body”.ExampleIn the following Java program, we are ...
Read MoreHow to run .SQL script using JDBC?
A database script file is a file that contains multiple SQL quries separated from each other. Usually, these files have the .sql extention.Running .sql script files in JavaYou can execute .sql script files in Java using the runScript() method of the ScriptRunner class of Apache iBatis. To this method you need to pass a connection object.Therefore to run a script file −Register the MySQL JDBC Driver using the registerDriver() method of the DriverManager class.Create a connection object to establish connection with the MySQL database using the getConnection() method.Initialize the ScriptRunner class of the package org.apache.ibatis.jdbc.Create a Reader object to read ...
Read MoreCan we create an object for the abstract class in java?
A method which does not have body is known as abstract method. It contains only method signature with a semi colon and, an abstract keyword before it.public abstract myMethod();To use an abstract method, you need to inherit it by extending its class and provide implementation to it.A class which contains 0 or more abstract methods is known as abstract class. If it contains at least one abstract method, it must be declared abstract.Instantiating an abstract classOnce a class is abstract it indicates that it may contain incomplete methods hence you cannot create an object of the abstract class.If you try ...
Read MoreIs there any alternative solution for static constructor in java?
The main purpose of constructors in Java is to initialize the instance variables of a class.But, if a class have Static variables you cannot initialize them using the constructors (you can assign values to static variables in constructors but in that scenario, we are just assigning values to static variables). because static variables are loaded into the memory before instantiation (i.e. before constructors are invoked)So, we should initialize static variables from static context. We cannot use static before constructors, Therefore, as an alternation to you can use static blocks to initialize static variables.Static blockA static block is a block of ...
Read MoreHow to insert data into a table with auto-incremented columns using JDBC?
While inserting data into a table with auto-incremented column, just leave that particular column out and insert remaining values by specifying the remaining columns using the following syntax of the INSERT statement −INSERT into table_name (column_name1, column_name2....) values(value1, value2....)ExampleLet us create a table with name sales in MySQL database, with one of the columns as auto-incremented, using CREATE statement as shown below −CREATE TABLE Sales( ID INT PRIMARY KEY AUTO_INCREMENT, ProductName VARCHAR (20), CustomerName VARCHAR (20), DispatchDate date, DeliveryTime time, Price INT, Location VARCHAR(20) );Following JDBC program establishes a connection with the database ...
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