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The java.text package provides a class named SimpleDateFormat which is used to format and parse dates in required manner (local).Using the methods of this class you can parse String to Date or, format Date to String.Formatting Date to StringYou can format a given String to Date object using the parse() method of the SimpleDateFormat class. To this method you need to pass the Date in String format. To format a String to Date object −Instantiate the SimpleDateFormat class by passing the required pattern of the date in String format to its constructor.//Instantiating the SimpleDateFormat class SimpleDateFormat formatter = new SimpleDateFormat("dd-MM-yyyy");Format/convert the ... Read More
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.Extending an abstract classOnce you extend an abstract class in Java you need to override all the abstractmethods in it or, declare it abstract. If you don’t, a ... Read More
Interface in Java is similar to class but, it contains only abstract methods and fields which are final and static.Private fields of an interfaceIf the fields of the interface are private, you cannot access them in the implementing class.If you try to declare the fields of an interface private, a compile time error is generated saying “modifier private not allowed here”.ExampleIn the following Java example, we are trying to declare the field and method of an interface private.public interface MyInterface{ private static final int num = 10; private abstract void demo(); }Compile time errorOn compiling, the above program ... Read More
Before getting into an example, we should know what thread is. A thread is a lightweight sub-process, it going to do background operations without interrupt to ui. This example demonstrate about How to avoid thread start twice in android.Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.Step 2 − Add the following code to res/layout/activity_main.xml. In the above code, we have taken edittext and textview. When user enter some text into edittext, it going to wait ... Read More
No, we cannot implement one interface from another you can just extend it using the extends keyword as −interface ArithmeticCalculations{ public abstract int addition(int a, int b); public abstract int subtraction(int a, int b); } interface MathCalculations implements ArithmeticCalculations{ public abstract double squareRoot(int a); public abstract double powerOf(int a, int b); }Still, if you try to implement one interface from another using the implements keyword. The compiler does not recognize the implements keyword after the name of the interface and throws a compile time error saying “'{' expected”.ExampleIn the following Java program, we have two interfaces ... Read More
Defining a class within an interface is allowed in Java. If the methods of an interface accept a class as an argument and the class is not used elsewhere, in such cases we can define a class inside an interface.ExampleIn the following example we have an interface with name CarRentalServices and this interface has two methods that accepts an object of the class Car as an argument. Within this interface we have the class Car. Live Demointerface CarRentalServices { void lendCar(Car c); void collectCar(Car c); public class Car{ int carId; String carModel; ... 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.Making an interface final.If you declare a class final cannot extend it. If you make a method final you cannot override it and, if you make a variable final you cannot modify it. i.e. use final with Java entities you cannot modify them further.If you make an interface final, you ... Read More
Interface in Java is similar to class but, it contains only abstract methods and fields which are final and static.In a separate class you need to implement this interface and provide body for all its abstract methods.Once you implement an interface using a class, you must provide body (implement) to all of its abstract methods or, should declare the class as abstract. If you don’t a compile time error will be generated for each unimplemented method saying “InterfaceExample is not abstract and does not override abstract method method_name in interface_name”.In the following java program, we have an interface with name ... Read More
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 More
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();Yes, you can throw and exception from an abstract class.ExampleIn the following Java program, we have a two classes: one abstract class with name MyClass which have an abstract method (display()) and, another class that extends the abstract class.Here, the display() method abstract class throws an IOException.Example Live Demoimport java.io.IOException; abstract class MyClass { public abstract void display() throws IOException; } public class AbstractClassExample extends MyClass{ public void display() throws IOException ... Read More