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import java.util.List; // interface
import java.util.Vector; // implementation of interface List
interface TestInterface {
public void run();
}
class Test0 implements TestInterface {
// simple inheritance and method overriding -> polymorphism
class Thing {
public void sayHello() { System.out.println(" class Thing says I'm a "+this.getClass().getName()); }
}
class Chicken extends Thing {
@Override
public void sayHello() { System.out.println(" class Chicken says I'm a "+this.getClass().getName()); }
}
class Egg extends Thing {
@Override
public void sayHello() { System.out.println(" class Egg says I'm a "+this.getClass().getName()); }
}
public void talk(Thing t) { t.sayHello(); }
@Override
public void run() {
System.out.println(this.getClass().getName());
talk(new Thing());
talk(new Chicken());
talk(new Egg());
}
}
class Test1 implements TestInterface {
// simple inheritance and method overriding -> polymorphism
// forcing method override with abstract class (can't be instanciated) and method
abstract class Thing {
// no default behavior
public abstract void sayHello();
// usage of abstract method that can't be modified
public final void talk() { sayHello(); }
}
class Chicken extends Thing {
@Override
public void sayHello() { System.out.println(" class Chicken says I'm a "+this.getClass().getName()); }
}
class Egg extends Thing {
@Override
public void sayHello() { System.out.println(" class Egg says I'm a "+this.getClass().getName()); }
}
@Override
public void run() {
System.out.println(this.getClass().getName());
(new Chicken()).talk();
(new Egg()).talk();
}
}
class Test2 implements TestInterface {
// wrong usage of an interface, this should be used for non related classes that would implement something in common
// ie: Interface Comparable, which specify the behavior of a particular data type
// or to take advantage of multiple inheritance of types.
interface Thing {
public void sayHello();
}
class Chicken implements Thing {
@Override
public void sayHello() { System.out.println(" class Chicken says I'm a "+this.getClass().getName()); }
}
class Egg implements Thing {
@Override
public void sayHello() { System.out.println(" class Egg says I'm a "+this.getClass().getName()); }
}
public void talk(Thing t) { t.sayHello(); }
@Override
public void run() {
System.out.println(this.getClass().getName());
talk(new Chicken());
talk(new Egg());
}
}
public class PatternInterfaceInheritance
{
public static void main (String [] args )
{
List<TestInterface> tests = new Vector<TestInterface>();
tests.add(new Test0());
tests.add(new Test1());
tests.add(new Test2());
for (TestInterface test : tests) test.run();
}
}
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