Notes

SHAPEE

public class Shape {
private String color;
public Shape(String color){
setColor(color);
}
public String getColor(){
return color;
}
public void setColor(String color) {
this.color = color;
}
@Override
public String toString() {
return "Shape[color=" + color + "]";
}

/** All shapes must provide a method called getArea() */
public double getArea() {
// We have a problem here!
// We need to return some value to compile the program.
System.err.println("Shape unknown! Cannot compute area!");
return 0;
}
}
RECTANGLEE
public class Rectangle extends Shape {
// Private member variables
private int length, width;

/** Constructs a Rectangle instance with the given color, length and width */
public Rectangle(String color, int length, int width) {
super(color);
this.length = length;
this.width = width;
}

/** Returns a self-descriptive string */
@Override
public String toString() {
return "Rectangle[length=" + length + ",width=" + width + "," + super.toString() + "]";
}

/** Override the inherited getArea() to provide the proper implementation for rectangle */
@Override
public double getArea() {
return length*width;
}


public void rectSpecMethod() {
System.out.println("rectangle...");

}
}
TRİANGLEE
public class Triangle extends Shape {
// Private member variables
private int base, height;

/** Constructs a Triangle instance with the given color, base and height */
public Triangle(String color, int base, int height) {
super(color);
this.base = base;
this.height = height;
}

/** Returns a self-descriptive string */
@Override
public String toString() {
return "Triangle[base=" + base + ",height=" + height + "," + super.toString() + "]";
}

/** Override the inherited getArea() to provide the proper implementation for triangle */
@Override
public double getArea() {
return 0.5*base*height;
}
public void triSpecMethod(){
System.out.println("triangle...");
}
}
TESTPOLYMORPİSHM

public class TestPolymorphism {

public static void main(String[] args) {
// TODO Auto-generated method stub
Shape[] shapes = new Shape[3];
shapes[0] = new Rectangle("red", 6, 4);
shapes[1] = new Triangle("blue", 8, 9);
shapes[2] = new Rectangle("black", 4,3);
System.out.println(shapes[0]); //System.out.println(shapes[0].toString());
System.out.println(shapes[1]); //System.out.println(shapes[1].toString());
System.out.println(shapes[2]); //System.out.println(shapes[2].toString());
for(int i = 0; i < shapes.length; i++) {
System.out.println(shapes[i]);
polyMethod(shapes[i]);
}
}
public static void polyMethod(Shape s) {
if(s instanceof Rectangle)
((Rectangle) s).rectSpecMethod();
else if( s instanceof Triangle)
((Triangle) s).triSpecMethod();
}

}