What is the main class in Java?

Inhaltsverzeichnis:

1. What is the main class in Java?
2. What is String [] args in Java?
3. Is Main a keyword in Java?
4. Can we override private method?
5. Can we inherit private method in Java?
6. Can a constructor override?
7. What happens if we override private method?
8. Are private methods final?
9. Can we override the final method in Java?
10. Why is @override used in Java?
11. Can a Java class be final?
12. Is string is thread safe in Java?
13. Is HashMap thread safe?
14. What is difference between string and StringBuffer?
15. Which is thread safe in Java?

What is the main class in Java?

The main() Method. A Java application is a public Java class with a main() method. The main() method is the entry point into the application. The signature of the method is always: public static void main(String[] args) Command-line arguments are passed through the args parameter, which is an array of String s.

What is String [] args in Java?

It is the identifier that the JVM looks for as the starting point of the java program. ... String[] args: It stores Java command line arguments and is an array of type java. lang. String class. Here, the name of the String array is args but it is not fixed and user can use any name in place of it.

Is Main a keyword in Java?

Main is not a keyword in Java. ... The language specification also mandates that there should be a method named "main", which should be public and static and accept an array of strings as parameter with the return type as void.

Can we override private method?

No, we cannot override private or static methods in Java. Private methods in Java are not visible to any other class which limits their scope to the class in which they are declared.

Can we inherit private method in Java?

A java private member cannot be inherited as it is available only to the declared java class. Since the private members cannot be inherited, there is no place for discussion on java runtime overloading or java overriding (polymorphism) features.

Can a constructor override?

Constructor looks like method but it is not. It does not have a return type and its name is same as the class name. But, a constructor cannot be overridden. If you try to write a super class's constructor in the sub class compiler treats it as a method and expects a return type and generates a compile time error.

What happens if we override private method?

private methods are hidden inside their class. They cannot be invoked directly by outside callers, such as main method in your case, because they are encapsulated inside the class. They do not participate in method overrides. No, a private method cannot be overridden since it is not visible from any other class.

Are private methods final?

So, to answer question 2, yes, all compilers will treat private methods as final . The compiler will not allow any private method to be overridden. Likewise, all compilers will prevent subclasses from overriding final methods.

Can we override the final method in Java?

Can We Override a Final Method? No, the Methods that are declared as final cannot be Overridden or hidden. ... Methods are declared final in java to prevent subclasses from Overriding them and changing their behavior, the reason this works is discussed at the end of this article.

Why is @override used in Java?

@Override @Override annotation informs the compiler that the element is meant to override an element declared in a superclass. Overriding methods will be discussed in Interfaces and Inheritance. While it is not required to use this annotation when overriding a method, it helps to prevent errors.

Can a Java class be final?

The main purpose of using a class being declared as final is to prevent the class from being subclassed. ... If a class is marked as final then no class can inherit any feature from the final class. You cannot extend a final class.

Is string is thread safe in Java?

String is immutable ( once created can not be changed )object . The object created as a String is stored in the Constant String Pool. Every immutable object in Java is thread safe ,that implies String is also thread safe . String can not be used by two threads simultaneously.

Is HashMap thread safe?

HashMap is non synchronized. It is not-thread safe and can't be shared between many threads without proper synchronization code whereas Hashtable is synchronized. It is thread-safe and can be shared with many threads.

What is difference between string and StringBuffer?

In Java programming language, strings are treated as objects. The Java platform provides the String class to create and manipulate strings. Whereas, StringBuffer class is a thread-safe, mutable sequence of characters. A string buffer is like a String, but can be modified.

Which is thread safe in Java?

A thread-safe class is a class that guarantees the internal state of the class as well as returned values from methods, are correct while invoked concurrently from multiple threads. The collection classes that are thread-safe in Java are Stack, Vector, Properties, Hashtable, etc.