//: reusing/CADSystem.java
// Ensuring proper cleanup.
package reusing;

class Shape{
    Shape(int i){
        System.out.println("Shape construstor");
    }
    void dispose(){
        System.out.println("Shape dispose");
    }
}
class Circle extends Shape{
    Circle(int i){
        super(i);
        System.out.println("Drawing Circle");
    }
    void dispose() {
        System.out.println("Erasing Circle");
        super.dispose();
    }
}
class Triangle extends Shape {
    Triangle(int i){
        super(i);
        System.out.println("Drawing Triangle");
    }
    void dispose() {
        System.out.println("Erasing Triangle");
    }
}
class Line extends Shape {
    private int start, end;
    Line(int start, int end){
        super(start);
        this.start = start;
        this.end = end;
        System.out.println("Drawing Line:" + start + "," + end);
    }
    void dispose() {
        System.out.println("Erasing Line:" + start + "," + end);
        super.dispose();
    }
}

public class CADSystem extends Shape {
    private Circle c;
    private Triangle t;
    private Line[] lines = new Line[3];
    public CADSystem(int i){
        super(i + 1);
        for(int j = 0; j < lines.length; j++)
            lines[j] = new Line(j, j*j);
        c = new Circle(1);
        t = new Triangle(1);
        System.out.println("Combined constructor");
    }
    public void dispose() {
        System.out.println("CADSystem.dispose()");
        // The order of initialization:
        t.dispose();
        c.dispose();
        for(int i = lines.length - 1; i >= 0; i--)
            lines[i].dispose();
        super.dispose();
    }
    public static void main(String[] args){
        CADSystem x = new CADSystem(47);
        try {  // 保护区
            // Code and exception handling...
            // 特殊处理
        } finally {            // finally子句中的代码总是要被执行的
            x.dispose();
        }
    }
}