117 lines
2.4 KiB
Java
117 lines
2.4 KiB
Java
// reuse/CADSystem.java
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// (c)2020 MindView LLC: see Copyright.txt
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// We make no guarantees that this code is fit for any purpose.
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// Visit http://OnJava8.com for more book information.
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// Ensuring proper cleanup
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// {java reuse.CADSystem}
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package reuse;
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class Shape {
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Shape(int i) {
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System.out.println("Shape constructor");
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}
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void dispose() {
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System.out.println("Shape dispose");
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}
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}
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class Circle extends Shape {
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Circle(int i) {
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super(i);
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System.out.println("Drawing Circle");
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}
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@Override
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void dispose() {
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System.out.println("Erasing Circle");
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super.dispose();
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}
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}
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class Triangle extends Shape {
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Triangle(int i) {
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super(i);
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System.out.println("Drawing Triangle");
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}
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@Override
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void dispose() {
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System.out.println("Erasing Triangle");
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super.dispose();
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}
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}
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class Line extends Shape {
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private int start, end;
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Line(int start, int end) {
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super(start);
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this.start = start;
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this.end = end;
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System.out.println(
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"Drawing Line: " + start + ", " + end);
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}
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@Override
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void dispose() {
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System.out.println(
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"Erasing Line: " + start + ", " + end);
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super.dispose();
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}
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}
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public class CADSystem extends Shape {
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private Circle c;
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private Triangle t;
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private Line[] lines = new Line[3];
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public CADSystem(int i) {
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super(i + 1);
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for(int j = 0; j < lines.length; j++)
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lines[j] = new Line(j, j*j);
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c = new Circle(1);
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t = new Triangle(1);
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System.out.println("Combined constructor");
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}
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@Override
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public void dispose() {
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System.out.println("CADSystem.dispose()");
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// The order of cleanup is the reverse
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// of the order of initialization:
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t.dispose();
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c.dispose();
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for(int i = lines.length - 1; i >= 0; i--)
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lines[i].dispose();
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super.dispose();
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}
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public static void main(String[] args) {
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CADSystem x = new CADSystem(47);
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try {
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// Code and exception handling...
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} finally {
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x.dispose();
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}
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}
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}
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/* Output:
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Shape constructor
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Shape constructor
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Drawing Line: 0, 0
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Shape constructor
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Drawing Line: 1, 1
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Shape constructor
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Drawing Line: 2, 4
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Shape constructor
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Drawing Circle
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Shape constructor
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Drawing Triangle
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Combined constructor
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CADSystem.dispose()
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Erasing Triangle
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Shape dispose
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Erasing Circle
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Shape dispose
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Erasing Line: 2, 4
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Shape dispose
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Erasing Line: 1, 1
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Shape dispose
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Erasing Line: 0, 0
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Shape dispose
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Shape dispose
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*/
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