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// reusing/Airplane.java

// TIJ4, Chapter Reusing, Exercise 1, page 241

/* Create a simple class. Inside a second class, define a reference to an object of

* the first class. Use lazy initialization to instantiate this object.

*/

import static org.greggordon.tools.Print.*;

class Engine {

private String s;

Engine() {

println("Engine()");

s = "Constructed";

}

public String toString() { return s; }

}

public class Airplane {

private String fuselage, wings, tail;

private Engine e;

public Airplane() {

println("Inside Airplane()");

fuselage = "Body";

wings = "Airfoils";

tail = "Empennage";

}

public String toString() {

if(e == null) // lazy (delayed) initialization:

e = new Engine();

return "fuselage = " + fuselage + ", " +

"wings = " + wings + ", " +

"tail = " + tail + ", " +

"Engine = " + e;

}

public static void main(String[] args) {

Airplane N1234 = new Airplane();

print(N1234);

}

}