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Articles by Maruthi Krishna
Page 14 of 50
Can We declare main() method as Non-Static in java?
The public static void main(String ar[]) method is the entry point of the execution in Java. When we run a .class file JVM searches for the main method and executes the contents of it line by line.You can write the main method in your program without the static modifier, the program gets compiled without compilation errors. But, at the time of execution JVM does not consider this new method (without static) as the entry point of the program. It searches for the main method which is public, static, with return type void, and a String array as an argument.public static int main(String[] ...
Read MoreWhat is overloading? What happens if we overload a main method in java?
Overloading is one of the mechanisms to achieve polymorphism. If a class contains two methods with the same name and different parameters, whenever you call this method the method body will be bound with the method call based on the parameters.ExampleIn the following Java program, the Calculator class has two methods with name addition. The only difference between them is that one contains 3 parameters and the other contains 2 parameters.Here, we can call the addition method by passing two integers or three integers. Based on the number of integer values we pass, the respective method will be executed.public class ...
Read MoreHow to write a class inside an interface in Java?
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.interface CarRentalServices { void lendCar(Car c); void collectCar(Car c); public class Car{ int carId; String carModel; ...
Read MoreCan we write an interface without any methods in java?
Yes, you can write an interface without any methods. These are known as marking interfaces or, tagging interfaces.A marker interface i.e. it does not contain any methods or fields by implementing these interfaces a class will exhibit a special behavior with respect to the interface implemented.ExampleConsider the following example, here we have class with name Student which implements the marking interface Cloneable. In the main method we are trying to create an object of the Student class and clone it using the clone() method.import java.util.Scanner; public class Student implements Cloneable { int age; String name; public Student ...
Read MoreWhat are unreachable blocks in java?
A code block/statement in Java to which the control never reaches and never gets executed during the lifetime of the program is known as unreachable block/statement.Generally, it happens whenever a piece of code hasA return statement before it.An infinite loop before it.Java does not support unreachable code. If you have any such statements, (which are unreachable) Java compiler raises a compile time error.Example1In the following Java program, the class UnreachableCodeExample has a method named greet which returns a String value. After the return statement it has a print statement.public class UnreachableCodeExample { public String greet() { ...
Read MoreWhile working with Java in eclipse I got a warning saying "dead code". What does it mean?
A code block/statement in Java to which the control never reaches and never gets executed during the lifetime of the program is known as unreachable block/statement.public class UnreachableCodeExample { public String greet() { System.out.println("This is a greet method "); return "Hello"; System.out.println("This is an unreachable code "); } public static void main(String args[]) { new UnreachableCodeExample().greet(); } }Dead codeA dead code is an unreachable code, but it doesn’t generate compile time error. But if you execute it in eclipse it gives you a warning.ExampleIn ...
Read MoreCan we define an abstract class without abstract method in java?\\n\\n
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.Abstract classA 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.And yes, you can declare abstract class without defining an abstract method in it. Once you declare a class abstract it indicates that the class is incomplete ...
Read MoreCan we declare an abstract method final or static 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.Declaring abstract method staticIf you declare a method in a class abstract to use it, you must override this method in the subclass. But, overriding is not possible with static methods. Therefore, an abstract method cannot be static.If you still, try to declare an abstract method static a compile time error is generated saying ...
Read MoreHow to create date object in Java?
Using the Date classYou can create a Date object using the Date() constructor of java.util.Date constructor as shown in the following example. The object created using this constructor represents the current time.Exampleimport java.util.Date; public class CreateDate { public static void main(String args[]) { Date date = new Date(); System.out.print(date); } }OutputThu Nov 02 15:43:01 IST 2018Using the SimpleDateFormat classUsing the SimpleDateFormat class and the parse() method of this you can parse a date string in the required format and create a Date object representing the specified date.Exampleimport java.text.ParseException; import java.text.SimpleDateFormat; ...
Read MoreHow to find a unique character in a string using java?
In this article, we will learn how to find a unique character in a string in Java. A unique character is a character that occurs only once in the string, while all others can occur multiple times. We can solve this problem using the following ways: Using Brute Force method. Using HashMap. Using brute force method To find a unique character in a given string, we will use a brute force approach. In the brute force approach, we will use two loops to compare each character to the rest of the string. Let's look at the steps: ...
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