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Java Articles
Page 28 of 450
Assigning arrays in Java.
While creating variables first of all we will declare them, initialize them, assign/re-assign values to them.Similarly, while creating arrays −You can declare an array just like a variable −int myArray[];You can create an array just like an object using the new keyword −myArray = new int[5];You can initialize the array by assigning values to all the elements one by one using the index −myArray [0] = 101; myArray [1] = 102;Assigning values to an arrayWhen we assign primitive values of one type to a variable of other (datatype) implicitly they are converted.But, when you try to assign a higher datatype ...
Read MoreAre Generics applied at compile time or run time?
Generics is a concept in Java where you can enable a class, interface and, method, accept all (reference) types as parameters. In other words it is the concept which enables the users to choose the reference type that a method, constructor of a class accepts, dynamically. By defining a class as generic you are making it type-safe i.e. it can act up on any datatype.Exampleclass Student{ T age; Student(T age){ this.age = age; } public void display() { System.out.println("Value of age: "+this.age); } } public class GenericsExample { ...
Read MoreCan you create an array of Generics type in Java?
Generics is a concept in Java where you can enable a class, interface and, method, accept all (reference) types as parameters. In other words it is the concept which enables the users to choose the reference type that a method, constructor of a class accepts, dynamically. By defining a class as generic you are making it type-safe i.e. it can act up on any datatype.Exampleclass Student{ T age; Student(T age){ this.age = age; } public void display() { System.out.println("Value of age: "+this.age); } } public class GenericsExample { ...
Read MoreHow many ways are there to initialize the instance variables of a class in java?
You can initialize the instance variables of a class using final methods, constructors or, Instance initialization blocks.Final methodsWhenever you make a method final, you cannot override it. i.e. you cannot provide implementation to the superclass’s final method from the subclass.i.e. The purpose of making a method final is to prevent modification of a method from outside (child class). You can also use these final methods to initialize the instance variables.Exampleimport java.util.Scanner; public class FinalMethods { int age = getAge(); String name = getName(); static Scanner sc = new Scanner(System.in); public static final int getAge() { ...
Read MoreWhat is need of introducing Generics, when Arrays already present in Java?
Arrays in Java are used to store homogeneous datatypes, where generics allow users to dynamically choose the type (class) that a method, constructor of a class accepts, dynamically.By defining a class generic you are making it type-safe i.e. it can act up on any datatype. To understand generics let us consider an example −Exampleclass Student{ T age; Student(T age){ this.age = age; } public void display() { System.out.println("Value of age: "+this.age); } } public class GenericsExample { public static void main(String args[]) { Student std1 ...
Read MoreIs it possible to instantiate Type-parameter in Java?
Generics is a concept in Java where you can enable a class, interface and, method, accept all (reference) types as parameters. In other words it is the concept which enables the users to choose the reference type that a method, constructor of a class accepts, dynamically. By defining a class as generic you are making it type-safe i.e. it can act up on any datatype.Exampleclass Student { T age; Student(T age){ this.age = age; } public void display() { System.out.println("Value of age: "+this.age); } } public class GenericsExample { ...
Read MoreIs it mandatory to use T for type-parameter, while defining Generics classes/methods in Java?
Generics is a concept in Java where you can enable a class, interface and, method, accept all (reference) types as parameters. In other words it is the concept which enables the users to choose the reference type that a method, constructor of a class accepts, dynamically. By defining a class as generic you are making it type-safe i.e. it can act up on any datatype.To define a generic class you need to specify the type parameter you are using in the angle brackets “” after the class name and you can treat this as datatype of the instance variable an ...
Read MoreCan we synchronize abstract methods in Java?
An abstract method is the one that does not have a body. It contains only a 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 (body) to it. If a class contains at least one abstract method, you must declare it abstract.Exampleimport java.io.IOException; abstract class MyClass { public abstract void display(); } public class AbstractClassExample extends MyClass{ public void display(){ System.out.println("subclass implementation of the display method"); } public static void main(String args[]) ...
Read MoreCan we have generic constructors in Java?
Generics is a concept in Java where you can enable a class, interface and, method, accept all (reference) types as parameters. In other words it is the concept which enables the users to choose the reference type that a method, constructor of a class accepts, dynamically. By defining a class as generic you are making it type-safe i.e. it can act up on any datatype.To define a generic class you need to specify the type parameter you are using in the angle brackets “” after the class name and you can treat this as datatype of the instance variable an ...
Read MoreCan we change the access specifier from (public) while implementing methods from interface in Java?
An interface in Java is a specification of method prototypes. Whenever you need to guide the programmer or, make a contract specifying how the methods and fields of a type should be you can define an interface.To create an object of this type you need to implement this interface, provide a body for all the abstract methods of the interface and obtain the object of the implementing class.All the methods of the interface are public and abstract and, we will define an interface using the interface keyword as shown below −interface MyInterface{ public void display(); public void setName(String ...
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