/* The following code example is taken from the book
 * "The C++ Standard Library - A Tutorial and Reference"
 * by Nicolai M. Josuttis, Addison-Wesley, 1999
 *
 * (C) Copyright Nicolai M. Josuttis 1999.
 * Permission to copy, use, modify, sell and distribute this software
 * is granted provided this copyright notice appears in all copies.
 * This software is provided "as is" without express or implied
 * warranty, and with no claim as to its suitability for any purpose.
 */
#include <iostream>
#include <valarray>
using namespace std;

// print three-dimensional valarray line-by-line
template<class T>
void printValarray3D (const valarray<T>& va, int dim1, int dim2)
{
    for (int i=0; i<va.size()/(dim1*dim2); ++i) {
        for (int j=0; j<dim2; ++j) {
            for (int k=0; k<dim1; ++k) {
                cout << va[i*dim1*dim2+j*dim1+k] << ' ';
            }
            cout << '\n';
        }
        cout << '\n';
    }
    cout << endl;
}

int main()
{
    /* valarray with 24 elements
     * - two groups
     * - four rows
     * - three columns
     */
    valarray<double> va(24);

    // fill valarray with values
    for (int i=0; i<24; i++) {
        va[i] = i;
    }

    // print valarray
    printValarray3D (va, 3, 4);

    // we need two two-dimensional subsets of three times 3 values
    // in two 12-element arrays
    size_t lengthvalues[] = {  2, 3 };
    size_t stridevalues[] = { 12, 3 };
    valarray<size_t> length(lengthvalues,2);
    valarray<size_t> stride(stridevalues,2);

    // assign the second column of the first three rows
    // to the first column of the first three rows
    va[gslice(0,length,stride)]
        = valarray<double>(va[gslice(1,length,stride)]);

    // add and assign the third of the first three rows
    // to the first of the first three rows
    va[gslice(0,length,stride)]
        += valarray<double>(va[gslice(2,length,stride)]);

    // print valarray
    printValarray3D (va, 3, 4);
}

/*
0 1 2
3 4 5
6 7 8
9 10 11

12 13 14
15 16 17
18 19 20
21 22 23


3 1 2
9 4 5
15 7 8
9 10 11

27 13 14
33 16 17
39 19 20
21 22 23



 */

&&&&&&&&&&&&&&&&&&&
Example demonstrating the use of packages.

    * Class1.java defined in package1.
    * Class2.java defined in package2.
    * Class3.java defined in package2.package3.
    * Class1.java defined in package4.
    * PackageExample.java Driver for package example
&&&&&&&&&&&&&&&&&&&&&
~~~~~~~~~~~~~~~~~~~~~
Class1.java defined in package1.
~~~~~~~~~~~~~~~~~~~~~
package package1;

*****************
 
public class Class1 {
  public static void printInfo() {
    System.out.println("This is Class1 in package1.");
  }
}
&&&&&&&&&&&&&&&&&&&&&
~~~~~~~~~~~~~~~~~~~~~
Class2.java defined in package2. 
~~~~~~~~~~~~~~~~~~~~~
package package2;
$$$$$$$$$$$$$$$$

public class Class2 {
  public static void printInfo() {
    System.out.println("This is Class2 in package2.");
  }
}
&&&&&&&&&&&&&&&&&&&&&&
~~~~~~~~~~~~~~~~~~~~~~
Class3.java defined in package2.package3
~~~~~~~~~~~~~~~~~~~~~~
package package2.package3;

@@@@@@@@@@@@@@@@@@@@@@@@@

public class Class3 {
  public static void printInfo() {
    System.out.println("This is Class3 in " +
                       "package2.package3.");
  }
}
&&&&&&&&&&&&&&&&&&&&&&&&&
~~~~~~~~~~~~~~~~~~~~~~~~~
Class1.java defined in package4.
~~~~~~~~~~~~~~~~~~~~~~~~~
package package4;

@@@@@@@@@@@@@@@@

public class Class1 {
  public static void printInfo() {
    System.out.println("This is Class1 in package4.");
  }
}
&&&&&&&&&&&&&&&&&&&&&&&&&&
~~~~~~~~~~~~~~~~~~~~~~~~~~
PackageExample.java Driver for package example.
~~~~~~~~~~~~~~~~~~~~~~~~~~
import package1.*;
import package2.Class2;
import package2.package3.*;

***************************

public class PackageExample {
  public static void main(String[] args) {
    Class1.printInfo();
    Class2.printInfo();
    Class3.printInfo();
    package4.Class1.printInfo();
  }
}
****************************

****************************
Code examples for interfaces:

    * Class1.java implements Interface1.java
    * Abstract Class2.java implements Interface1.java and Interface2.java
    * Class3.java extends abstract class Class2.java
    * Interface3.java extends Interface1.java and Interface2.java
***************************
~~~~~~~~~~~~~~~~~~~~~~~~~~~
Class1.java 
~~~~~~~~~~~~~~~~~~~~~~~~~~~

// This class is not abstract, so it must provide 
// implementations of method1 and method2.

public class Class1 extends SomeClass
                    implements Interface1 {
  public ReturnType1 method1(ArgType1 arg) {
    someCodeHere();
    ...
  }
                      
  public ReturnType2 method2(ArgType2 arg) {
        someCodeHere();
    ...
  }

  ...
}
>>>>>>>>>>>>>>>>>>>>>>>>>>
~~~~~~~~~~~~~~~~~~~~~~~~~~
Interface1.java
~~~~~~~~~~~~~~~~~~~~~~~~~~
public interface Interface1 {
   ReturnType1 method1(ArgType1 arg);
  ReturnType2 method2(ArgType2 arg);
}
>>>>>>>>>>>>>>>>>>>>>>>>>>
~~~~~~~~~~~~~~~~~~~~~~~~~~
Abstract Class2.java implements Interface1.java and Interface2.java
~~~~~~~~~~~~~~~~~~~~~~~~~~
Class2.java 
~~~~~~~~~~~~~~~~~~~~~~~~~~

// This class is abstract, so does not have to provide
// implementations of the methods of Interface 1 and 2.

public abstract class Class2 extends SomeOtherClass
                             implements Interface1,
                                        Interface2 {
  ...
}
>>>>>>>>>>>>>>>>>>>>>>>>>
~~~~~~~~~~~~~~~~~~~~~~~~~
Interface2.java
~~~~~~~~~~~~~~~~~~~~~~~~~

public interface Interface2 {
  ReturnType3 method3(ArgType3 arg);
}
~~~~~~~~~~~~~~~~~~~~~~~~~
# Class3.java extends abstract class Class2.java 
~~~~~~~~~~~~~~~~~~~~~~~~~
Class3.java
>>>>>>>>>>>>>>>>>>>>>>>>>

// This class is not abstract, so it must provide
// implementations of method1, method2, and method3.

public class Class3 extends Class2 {
  public ReturnType1 method1(ArgType1 arg) {
    someCodeHere();
    ...
  }
                      
  public ReturnType2 method2(ArgType2 arg) {
       someCodeHere();
    ...
  }

  public ReturnType3 method3(ArgType3 arg) {
     someCodeHere();
    ...
  }

  ...
}
>>>>>>>>>>>>>>>>>>>>>>>
# Interface3.java extends Interface1.java and Interface2.java
>>>>>>>>>>>>>>>>>>>>>>>
~~~~~~~~~~~~~~~~~~~~~~
Interface3.java 
~~~~~~~~~~~~~~~~~~~~~~

// This interface has three methods (by inheritance) and 
// two constants.

public interface Interface3 extends Interface1,
                                    Interface2 {
  int MIN_VALUE = 0;
  int MAX_VALUE = 1000;
}
<<<<<<<<<<<<<<<<<<<<<

************************
Ship.java A Ship class illustrating object-oriented programming concepts. Incorporates Javadoc comments. See ShipTest.java for a test. 
************************
/** Ship example to demonstrate OOP in Java.
 *
 *  @author 
 *          Larry Brown
 *  @version 2.0
 */

public class Ship {
  // Instance variables

  private double x=0.0, y=0.0, speed=1.0, direction=0.0;
  private String name;

  // Constructors

  /** Build a ship with specified parameters. */

  public Ship(double x, double y, double speed,
              double direction, String name) {
    setX(x);
    setY(y);
    setSpeed(speed);
    setDirection(direction);
    setName(name);
  }

  /** Build a ship with default values
   *  (x=0, y=0, speed=1.0, direction=0.0).
   */

  public Ship(String name) {
    setName(name);
  }

  /** Move ship one step at current speed/direction. */

  public void move() {
    moveInternal(1);
  }

  /** Move N steps. */

  public void move(int steps) {
    moveInternal(steps);
  }

  private void moveInternal(int steps) {
    double angle = degreesToRadians(direction);
    x = x + (double)steps * speed * Math.cos(angle);
    y = y + (double)steps * speed * Math.sin(angle);
  }

  private double degreesToRadians(double degrees) {
    return(degrees * Math.PI / 180.0);
  }

  /** Report location to standard output. */

  public void printLocation() {
    System.out.println(getName() + " is at (" + getX() +
                       "," + getY() + ").");
  }

  /** Get current X location. */

  public double getX() {
    return(x);
  }

  /** Set current X location. */

  public void setX(double x) {
    this.x = x;
  }

  /** Get current Y location. */

  public double getY() {
    return(y);
  }

  /** Set current Y location. */

  public void setY(double y) {
    this.y = y;
  }

  /** Get current speed. */

  public double getSpeed() {
    return(speed);
  }

  /** Set current speed. */

  public void setSpeed(double speed) {
    this.speed = speed;
  }

  /** Get current heading (0=East, 90=North, 180=West,
   *  270=South).  I.e., uses standard math angles, not
   *  nautical system where 0=North, 90=East, etc.
   */

  public double getDirection() {
    return(direction);
  }

  /** Set current direction (0=East, 90=North, 180=West,
   *  270=South). I.e., uses standard math angles,not
   *  nautical system where 0=North,90=East, etc.
   */

  public void setDirection(double direction) {
    this.direction = direction;
  }

  /** Get Ship's name. Can't be modified by user. */

  public String getName() {
    return(name);
  }

  private void setName(String name) {
    this.name = name;
  }
}
*********************
ShipTest.java 
*********************
public class ShipTest {
 public static void main(String[] args) {
    Ship s1 = new Ship("Ship1"); 
    Ship s2 = new Ship(0.0, 0.0, 2.0, 135.0, "Ship2");
    s1.move();
    s2.move(3);
    s1.printLocation();
    s2.printLocation();
  }
}

Test1.java Accesses instance variables in a Ship object. 
********************************************************

// Create a class with five instance variables (fields):
// x, y, speed, direction, and name. Note that Ship1 is 
// not declared "public", so it can be in the same file as
// Test1. A Java file can only contain one "public" class
// definition.

class Ship1 {
  public double x, y, speed, direction;
  public String name;
}

// The "driver" class containing "main".

public class Test1 {
  public static void main(String[] args) {
    Ship1 s1 = new Ship1();
    s1.x = 0.0;
    s1.y = 0.0;
    s1.speed = 1.0;
    s1.direction = 0.0;   // East
    s1.name = "Ship1";
    Ship1 s2 = new Ship1();
    s2.x = 0.0;
    s2.y = 0.0;
    s2.speed = 2.0;
    s2.direction = 135.0; // Northwest
    s2.name = "Ship2";
    s1.x = s1.x + s1.speed
           * Math.cos(s1.direction * Math.PI / 180.0);
    s1.y = s1.y + s1.speed
           * Math.sin(s1.direction * Math.PI / 180.0);
    s2.x = s2.x + s2.speed
           * Math.cos(s2.direction * Math.PI / 180.0);
    s2.y = s2.y + s2.speed
           * Math.sin(s2.direction * Math.PI / 180.0);
    System.out.println(s1.name + " is at ("
                       + s1.x + "," + s1.y + ").");
    System.out.println(s2.name + " is at ("
                       + s2.x + "," + s2.y + ").");
  }
}
**********************

******************
ShowArgs.java Application that reports all command-line arguments.
******************
 */

public class ShowArgs {
  public static void main(String[] args) {
    for(int i=0; i

DropBall.java Uses a while loop to determine how long it takes a ball to fall from the top of the Washington Monument to the ground
************************************************************
/** Simulating dropping a ball from the top of the Washington
 *  Monument. The program outputs the height of the ball each
 *  second until the ball hits the ground.
 *
 *****************************************

public class DropBall {
  public static void main(String[] args) {
    int time = 0;
    double start = 550.0, drop = 0.0;
    double height = start;
    while (height > 0) {
      System.out.println("After " + time + 
                   (time==1 ? " second, " : " seconds,") + 
                   "the ball is at " + height + " feet.");
      time++;                   
      drop = freeFall(time);
      height = start - drop;
    }
    System.out.println("Before " + time + " seconds could " +
                       "expire, the ball hit the ground!");
  }
  
  /** Calculate the distance in feet for an object in 
   *  free fall. 
   */

  public static double freeFall (float time) {
    // Gravitational constant is 32 feet per second squared
    return(16.0 * time * time); // 1/2 gt^2
  }
}
@@@@@@@@@@@@@@@@@@@@