JAVA 第章第一部分程序.doc

示例程序4-1 Rectangle类 public class Retangle { public Retangle(double l, double w) { length = l; width = w; } public double calcPerimeter() { return 2 * (length + width); } public double calcArea() { return length * width; } public String toString() { return 长为 + length + 宽为 + width + 的长方形; } protected double length; private double width; } 示例程序4-2 Square类 public class Square extends Retangle { public Square(double side) { super(side,side); } public double calcPerimeter() { return length * 4; } public String toString() { return 边长为 + length + 的正方形; } } 示例程序4-3 几何形状的测试程序 public class ShapeTest { public static void main(String[] args) { Retangle retangle = new Retangle(10.0, 20.0); Square square = new Square(10.0); System.out.println(retangle + 周长： + retangle.calcPerimeter()); System.out.println(retangle + 面积： + retangle.calcArea()); System.out.println(square + 周长： + square.calcPerimeter()); System.out.println(square + 面积： + square.calcArea()); } } 示例程序4-4 Berry public class Berry extends Fruit { public Berry(String fname, int in) { super(fname, in); } public int gain() { int g ; if (input200) { g = super.gain()-200; //种植浆果类则需要另外缴纳200元的许可证费用 } else { g = 0; } System.out.println(fruitName + 投入 + input + 净收益 + g); return g; } } 示例程序4-5 CitrusFruit public class CitrusFruit extends Fruit { public CitrusFruit(String fname, int in) { super(fname, in); } public int gain() { int g = input * 3; // 种植柑橘类净收益是投入的3倍 System.out.println(fruitName + 投入 + input + 净收益 + g); return g; } } 示例程序4-6 TropicalFruit public class TropicalFruit extends Fruit { public TropicalFruit (String fname, int in) { super(fname, in); } public int gain() { i