class Point
{
private double xCoordinate;
private double yCoordinate;
public Point(){}
public Point(double x,double y)
{
xCoordinate=x;
yCoordinate=y;
}
public String toString()
{
return "("+Double.toString(xCoordinate)+","
+Double.toString(yCoordinate)+")";
}
} class Ball
{
private Point center;
private double radius;
private String colour;
public void Ball(){}
public void Ball(double xValue,double yValue,double r)
{
center=new Point(xValue,yValue);
radius=r;
}
public void Ball(double xValue,double yValue,double r,String c)
{
this(xValue,yValue,r);
colour=c;
}
public String toString()
{
return "A ball with center"+center.toString()+",radius"+
Double.toString(radius)+",colour"+colour;
}}class MovingBall extends Ball
{
private double speed;
public MovingBall(double xValue,double yValue,double r,String c,double s)
{
super(xValue,yValue,r,c);
speed=s;
}
public String toString()
{
return super.toString()+",speed"+Double.toString(speed);
}
}public class Tester
{
public static void main(String vrgs[])
{
MovingBall mb=new MovingBall(10,20,40,"Green",25);
System.out.println(mb);
}
}
C:\Documents and Settings\AABB>d:D:\>cd javaD:\java>javac Tester.java
Tester.java:31: 对 this 的调用必须是构造函数中的第一个语句
this(xValue,yValue,r);
^
Tester.java:47: 找不到符号
符号: 构造函数 Ball(double,double,double,java.lang.String)
位置: 类 Ball
super(xValue,yValue,r,c);
^
2 错误D:\java>怎改呢!
{
private double xCoordinate;
private double yCoordinate;
public Point(){}
public Point(double x,double y)
{
xCoordinate=x;
yCoordinate=y;
}
public String toString()
{
return "("+Double.toString(xCoordinate)+","
+Double.toString(yCoordinate)+")";
}
} class Ball
{
private Point center;
private double radius;
private String colour;
public void Ball(){}
public void Ball(double xValue,double yValue,double r)
{
center=new Point(xValue,yValue);
radius=r;
}
public void Ball(double xValue,double yValue,double r,String c)
{
this(xValue,yValue,r);
colour=c;
}
public String toString()
{
return "A ball with center"+center.toString()+",radius"+
Double.toString(radius)+",colour"+colour;
}}class MovingBall extends Ball
{
private double speed;
public MovingBall(double xValue,double yValue,double r,String c,double s)
{
super(xValue,yValue,r,c);
speed=s;
}
public String toString()
{
return super.toString()+",speed"+Double.toString(speed);
}
}public class Tester
{
public static void main(String vrgs[])
{
MovingBall mb=new MovingBall(10,20,40,"Green",25);
System.out.println(mb);
}
}
C:\Documents and Settings\AABB>d:D:\>cd javaD:\java>javac Tester.java
Tester.java:31: 对 this 的调用必须是构造函数中的第一个语句
this(xValue,yValue,r);
^
Tester.java:47: 找不到符号
符号: 构造函数 Ball(double,double,double,java.lang.String)
位置: 类 Ball
super(xValue,yValue,r,c);
^
2 错误D:\java>怎改呢!
好象很多地方乱
class Ball 有继承 Point吗 ?
第二改 把构造的void全去掉
运行结果
A ball with center ( 10.0, 20.0) ,radius 40.0,colour Green ,speed 25.0
不知道对不对,没仔细看,自己再瞅瞅,我也是新手
public void Ball(){}
public void Ball(double xValue,double yValue,double r)
{
center=new Point(xValue,yValue);
radius=r;
}
public void Ball(double xValue,double yValue,double r,String c)
{
this(xValue,yValue,r);
colour=c;
}
汗~!
private double xCoordinate;
private double yCoordinate;
public Point(double x, double y) {
xCoordinate = x;
yCoordinate = y;
}
public String toString() {
return "( "+Double.toString(xCoordinate)+ ", "
+Double.toString(yCoordinate)+ ") ";
}
} class Ball {
private Point center;
private double radius;
private String colour;
public Ball(double xValue, double yValue, double r) {
center = new Point(xValue,yValue);
radius = r;
}
public Ball(double xValue,double yValue,double r,String c) {
this(xValue,yValue,r);
colour = c;
}
public String toString() {
return "A ball with center "+center.toString()+ ",radius="+
Double.toString(radius)+ ",colour is "+colour;
} } class MovingBall extends Ball {
private double speed;
public MovingBall(double xValue,double yValue, double r, String c, double s) {
super(xValue,yValue,r,c);
speed = s;
}
public String toString() {
return super.toString()+ ",speed is "+Double.toString(speed);
}
} public class Tester {
public static void main(String[] args) {
MovingBall mb=new MovingBall(10,20,40, "Green ",25);
System.out.println(mb);
}
}
结果为A ball with center ( 10.0, 20.0) ,radius=40.0,colour is Green ,speed is 25.0
主要是构造函数 void去掉