【菜鸟求助】程序错误，求大师指点，不甚感激。
新手学习Java，按照书上所说写了如下程序，目的是求两个点之间的距离。

public class point
{ public double x,y;
public double distance(point that)
{double xdiff,ydiff;
xdiff=x-that.x;
ydiff=y-that.y;
return Math.sqrt(xdiff*xdiff+ydiff*ydiff);
}
point point1=new point();
point point2=new point();
point1.x=0.0;
point1.y=0.0;
point2.x=5.0;
point2.y=10.0;
d=point1.distance(point2);
System.out.println(d);
}

编译时提示倒数第3行至倒数第六行的x和y有错误。

[解决办法]
你贴出来的是point类的完整代码吗？如果是的，你见过把代码块直接写类里面的吗？

point point1=new point();
point point2=new point();
point1.x=0.0;
point1.y=0.0;
point2.x=5.0;
point2.y=10.0;
d=point1.distance(point2);
System.out.println(d);

把这一块放方法里封装起来，还有你的变量d没有定义。

java不允许在类里面直接写代码的
[解决办法]
class point {
public double x,y;
public double distance(point that)
{double xdiff,ydiff;
xdiff=x-that.x;
ydiff=y-that.y;
return Math.sqrt(xdiff*xdiff+ydiff*ydiff);
}
}
public class yy{
public static void main(String[] args){
double d;
point point1=new point();
point point2=new point();
point1.x=0.0;
point1.y=0.0;
point2.x=5.0;
point2.y=10.0;
d=point1.distance(point2);
System.out.println(d);
}
}

帮你改了