What is the output of this program ?

class main_arguments {
            public static void main(String [ ] args)
            {
                String [][] argument = new String[2][2];
                int x;
                argument[0] = args;
                x = argument[0].length;
                for (int y = 0; y < x; y++)
                    System.out.print(" " + argument[0][y]);           
            }
        }

Path contains path of .exe files(commands).

Classpath contains path of packages. packages can be stored in folder or .jar files

JAR files are java's version of ZIP files. In fact, JAR uses the ZIP file format.

uses:

- to compress a number of . class files into one file

- to make a java executable JAR file.

Unwrapping is also called as unpacking or unboxing.

Getting the private data stored in the object by using methods is called unpacking or unwrapping.

Wrapping is also called as packing or boxing.

Storing the data inside the object as private data which can accessed outside the class only by using methods.

String class objects are immutable objects and they represents strings( sequence of characters)

StringBuffer class objects are mutable objects representing strings and they are Thread safe

StringBuild class objects are also mutable objects representing strings and they are not Thread safe

new ClassName( arg1, arg2, .... argN);

Ex:

Class sample {

   Sample(int a) {

   System.out.println("arg con a =" +a);

   }

}

class Demo {

    Public static void main( String[] args) {

     Sample s1= new Sample(23);

     Sample s2= new Sample(45);

    }

}

Constructor is not a special method.

Constructor is block of code that is executed automatically whenever object of the class is created.

Method contains name, parameters, return type and executable body. But block does not contains name, parameters, return type.It contains only executable body.

Methods are executed by method call statements. Blocks are executed automatically with class loading and with object creation.