oliver456
发贴: 12
积分: 1
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于 2005-09-27 18:37
class Point { protected int x,y; public Point(int a,int b) { x=a; y=b; System.out.println("1: " + this); // print this } public String toString() { return "[" + x + "," + y + "]"; } } class Circle extends Point { protected double radius=9.0; public Circle(int a,int b) { super(a,b); System.out.println("2: " + this); // print this } public Circle(double r,int a,int b) { super(a,b); radius=r; System.out.println("2: " + this); // print this } public String toString() { return "Center = " + super.toString() + ", Radius = " + radius; } } public class Test { public static void main(String[] args) { Point p1,p11; // from Circle to Point, we don't need to cast here p11=new Circle(72,29); p1 = new Circle(4.5,72,29); } } 下面是运行结果
C:\>javac Test.java C:\>java -cp . Test 1: Center = [72,29], Radius = 0.0 2: Center = [72,29], Radius = 9.0 1: Center = [72,29], Radius = 0.0 2: Center = [72,29], Radius = 4.5
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