Java Questions

Reserved words are words that cannot be used as object or variable names in a Java program because they're already used by the syntax of the Java programming language.

Java reserved words are keywords that are reserved by Java functions or other uses that cannot be used as identifiers (e.g., variable names, function names, class names).

If a reserved word was used as a variable you would get an error or unexpected result.

Examples : Int, Long, Abstract, Class, Break, Catch, Case, Public, Static, Void,...

String Args (String []) is an array of parameters of type String.

In Java, 'args' contains the supplied command-line arguments as an array of String objects. In other words, if you run your program as 'java MyProgram Hello World' then 'args' will contain ["Hello", "World"]. When a java class is executed from the console, the main method is what is called.

A static variable in Java belongs to its class and its value remains the same for all its instances. A static variable is initialized when the class is loaded by the JVM. If your code tries to access a non-static variable, without any instance, the compiler will complain, because those variables are not created yet and they are not associated with any instance.

Java Collections Framework provides a well designed set of interfaces and classes that support operations on a collections of objects. The most basic interfaces that reside in the Java Collections Framework are:

Collection, which represents a group of objects known as its elements.

Set, which is a collection that cannot contain duplicate elements.

List, which is an ordered collection and can contain duplicate elements.

Map, which is an object that maps keys to values and cannot contain duplicate keys.

Final method is a method defined in the super class with final modifier.

We cannot overriding final method of super class in the sub class.

EX:

 Class Sample {

   final void funOne() {

   }

   void funTwo() {

   }

}

Class Sub extends Sample {

  void funOne() { // overriding is not allowed

  }

  viod funTwo() { //overriding is allowed

  }

}

In single virtual machine,JVM passes arguments only by value.