Why Thread is not an abstract class?

If the Thread class was declared as abstract , the language would have to provide another class that extended from it which programmers could use to create a Thread . Your question would then be about why this class that extends from Thread is not abstract .

Is Thread a abstract class?

Thread is not an abstract class. When an object implementing interface Runnable is used to create a thread, starting the thread causes the object’s run method to be called in that separately executing thread.

Why would you use an abstract method instead of a non abstract one?

Abstract method basically says, that there is no implementation of the method and it needs to be implemented in a subclass. However if you had an abstract method in a non-abstract class, you could instantiate the class and get an object, that would have an unimplemented method, which you would be unable to call.

What is the main reason for using abstract classes?

The short answer: An abstract class allows you to create functionality that subclasses can implement or override. An interface only allows you to define functionality, not implement it. And whereas a class can extend only one abstract class, it can take advantage of multiple interfaces.

Which of the following are not the methods of the Thread class?

exit() method terminates the currently running Java Virtual Machine. It is a status code where a nonzero or 1 indicates abnormal termination of the program whereas zero or 0 indicates normal termination of the program. It is not included in the thread class as it is not the part of the execution cycle of the method.

Which of these is not an abstract classes?

Which of these is not abstract? Explanation: Thread is not an abstract class.

Which one of the following is not a method in the thread class?

What is the purpose of abstract class Mcq?

The purpose of an abstract class is to provide an appropriate base class from which other classes can inherit.

How can we use abstract class method in Java?

To declare an abstract method, use this general form: abstract type method-name(parameter-list); As you can see, no method body is present. Any concrete class(i.e. class without abstract keyword) that extends an abstract class must override all the abstract methods of the class.

What is the use of abstractabstract method in Java?

Abstract method is always in abstract class and when you extend the abstract class, you have to implement that method in your sub class else you will get compilation error. Which means you are defining a template for the sub classes.

Should a method always be declared in an abstract class?

A method must always be declared in an abstract class, or in other words you can say that if a class has an abstract method, it should be declared abstract as well. In the last tutorial we discussed Abstract class, if you have not yet checked it out read it here: Abstract class in Java, before reading this guide.

What is the use of abstract keyword with classes and methods?

Any concrete class (i.e. class without abstract keyword) that extends an abstract class must override all the abstract methods of the class. Any class that contains one or more abstract methods must also be declared abstract Consider the following Java program, that illustrate the use of abstract keyword with classes and methods.

Can abstract classes be used to create object references in Java?

Note: Although abstract classes cannot be used to instantiate objects, they can be used to create object references, because Java’s approach to run-time polymorphism is implemented through the use of super-class references. Thus, it must be possible to create a reference to an abstract class so that it can be used to point to a subclass object.