Details

import java.util.Scanner;

public class Echo
{
  public static void main (String[] args)
  {
    String inData;
    Scanner scan = new Scanner( System.in );

    System.out.println("Enter the data:");
    inData = scan.nextLine();

    System.out.println("You entered:" + inData );
  }
}

Later on we will do something special to convert strings of digits into primitive numeric types. This program does not do that.

public class Echo

The program defines a class named Echo that contains a single method, its main() method.

public static void main ( String[] args )

All main() methods start this way. Every program should have a main() method.

String inData;

The program creates a reference variable inData which will soon refer to a String object.

Scanner scan = new Scanner( System.in );

This creates a Scanner object, referred to by the reference variable scan.