java : add PatternInterfaceInheritance.java

1 files changed, 102 insertions, 0 deletions

diff --git a/java/PatternInterfaceInheritance.java b/java/PatternInterfaceInheritance.java
new file mode 100644
index 0000000..a4897df
--- /dev/null
+++ b/java/PatternInterfaceInheritance.java
@@ -0,0 +1,102 @@
+
+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();
+    }
+}
+