// references/CopyConstructor.java

// (c)2016 MindView LLC: see Copyright.txt

// We make no guarantees that this code is fit for any purpose.

// Visit http://mindviewinc.com/Books/OnJava/ for more book information.

// A constructor to copy an object of the same

// type, as an attempt to create a local copy

import java.lang.reflect.*;

class FruitQualities {

private int weight;

private int color;

private int firmness;

private int ripeness;

private int smell;

// etc.

// No-arg constructor:

public FruitQualities() {

// Do something meaningful...

}

// Other constructors:

// ...

// Copy constructor:

public FruitQualities(FruitQualities f) {

weight = f.weight;

color = f.color;

firmness = f.firmness;

ripeness = f.ripeness;

smell = f.smell;

// etc.

}

}

class Seed {

// Members...

public Seed() { /* No-arg constructor */ }

public Seed(Seed s) { /* Copy constructor */ }

}

class Fruit {

private FruitQualities fq;

private int seeds;

private Seed[] s;

public Fruit(FruitQualities q, int seedCount) {

fq = q;

seeds = seedCount;

s = new Seed[seeds];

for(int i = 0; i < seeds; i++)

s[i] = new Seed();

}

// Other constructors:

// ...

// Copy constructor:

public Fruit(Fruit f) {

fq = new FruitQualities(f.fq);

seeds = f.seeds;

s = new Seed[seeds];

// Call all Seed copy-constructors:

for(int i = 0; i < seeds; i++)

s[i] = new Seed(f.s[i]);

// Other copy-construction activities...

}

// This allows derived constructors (or other

// methods) to put in different qualities:

protected void addQualities(FruitQualities q) {

fq = q;

}

protected FruitQualities getQualities() {

return fq;

}

}

class Tomato extends Fruit {

public Tomato() {

super(new FruitQualities(), 100);

}

public Tomato(Tomato t) { // Copy-constructor

super(t); // Upcast to base copy-constructor

// Other copy-construction activities...

}

}

class ZebraQualities extends FruitQualities {

private int stripedness;

// No-arg constructor:

public ZebraQualities() {

super();

// do something meaningful...

}

public ZebraQualities(ZebraQualities z) {

super(z);

stripedness = z.stripedness;

}

}

class GreenZebra extends Tomato {

public GreenZebra() {

addQualities(new ZebraQualities());

}

public GreenZebra(GreenZebra g) {

super(g); // Calls Tomato(Tomato)

// Restore the right qualities:

addQualities(new ZebraQualities());

}

public void evaluate() {

ZebraQualities zq =

(ZebraQualities)getQualities();

// Do something with the qualities

// ...

}

}

public class CopyConstructor {

public static void ripen(Tomato t) {

// Use the "copy constructor":

t = new Tomato(t); // (1)

System.out.println("In ripen, t is a " +

t.getClass().getName());

}

public static void slice(Fruit f) {

f = new Fruit(f); // Hmmm... will this work? (2)

System.out.println("In slice, f is a " +

f.getClass().getName());

}

@SuppressWarnings("unchecked")

public static void ripen2(Tomato t) {

try {

Class c = t.getClass();

// Use the "copy constructor":

Constructor ct =

c.getConstructor(new Class[] { c });

Object obj =

ct.newInstance(new Object[] { t });

System.out.println("In ripen2, t is a " +

obj.getClass().getName());

} catch(NoSuchMethodException |

SecurityException |

InstantiationException |

IllegalAccessException |

IllegalArgumentException |

InvocationTargetException e) {

System.out.println(e);

}

}

@SuppressWarnings("unchecked")

public static void slice2(Fruit f) {

try {

Class c = f.getClass();

Constructor ct =

c.getConstructor(new Class[] { c });

Object obj =

ct.newInstance(new Object[] { f });

System.out.println("In slice2, f is a " +

obj.getClass().getName());

} catch(NoSuchMethodException |

SecurityException |

InstantiationException |

IllegalAccessException |

IllegalArgumentException |

InvocationTargetException e) {

System.out.println(e);

}

}

public static void main(String[] args) {

Tomato tomato = new Tomato();

ripen(tomato); // OK

slice(tomato); // OOPS!

ripen2(tomato); // OK

slice2(tomato); // OK

GreenZebra g = new GreenZebra();

ripen(g); // OOPS!

slice(g); // OOPS!

ripen2(g); // OK

slice2(g); // OK

g.evaluate();

}

}

/* Output:

In ripen, t is a Tomato

In slice, f is a Fruit

In ripen2, t is a Tomato

In slice2, f is a Tomato

In ripen, t is a Tomato

In slice, f is a Fruit

In ripen2, t is a GreenZebra

In slice2, f is a GreenZebra

*/