Rectangle class in the following uses a constructor to set the dimensions:
class Rectangle {
double width;
double height;
Rectangle() {
width = 10;
height = 10;
}
double area() {
return width * height;
}
}
public class Main {
public static void main(String args[]) {
Rectangle mybox1 = new Rectangle();
double area;
area = mybox1.area();
System.out.println("Area is " + area);
}
}
When this program is run, it generates the following results:
Area is 100.0
The constructors can also have parameters. Usually the parameters are used to set the initial states of the object.
class Rectangle {
double width;
double height;
Rectangle(double w, double h) {
width = w;
height = h;
}
double area() {
return width * height;
}
}
public class Main {
public static void main(String args[]) {
Rectangle mybox1 = new Rectangle(10, 20);
double area;
area = mybox1.area();
System.out.println("Area is " + area);
}
}
The output from this program is shown here:
Area is 200.0
class Rectangle {
double width;
double height;
Rectangle(Rectangle ob) { // pass object to constructor
width = ob.width;
height = ob.height;
}
Rectangle(double w, double h) {
width = w;
height = h;
}
// constructor used when no dimensions specified
Rectangle() {
width = -1; // use -1 to indicate
height = -1; // an uninitialized
}
// constructor used when cube is created
Rectangle(double len) {
width = height = len;
}
double area() {
return width * height;
}
}
public class Main {
public static void main(String args[]) {
Rectangle mybox1 = new Rectangle(10, 20);
Rectangle myclone = new Rectangle(mybox1);
double area;
// get volume of first box
area = mybox1.area();
System.out.println("Area of mybox1 is " + area);
// get volume of clone
area = myclone.area();
System.out.println("Area of clone is " + area);
}
}
The output:
Area of mybox1 is 200.0
Area of clone is 200.0| java2s.com | Contact Us | Privacy Policy |
| Copyright 2009 - 12 Demo Source and Support. All rights reserved. |
| All other trademarks are property of their respective owners. |