问题描述

为什么需要标示符，求大神。在第三行代码，编译时出错。

class Point{
double x,y,z;

 Point(double_x,double_y,double_z ) {
x=_x;
y=_y;
z=_z;
}

void setX(double _x){
x=_x;
}
void setY(double _y){
y=_y;
}
void setZ(double_z){
z=_z;
}
double getDistance(Point P){
    return(x-p.x)*(x-p.x)+(y-p.y)*(y-p.y)+(z-p.z)*(z-p.z);
}

}
public class TestPoint{
public static void main(String[]args){
Point p=new Point(1.0,2.0,3.0);
Point p1=new Point(0.0,0.0,0.0);
System.out.println(p.getdistance(p1));

    p.setX(5.0);在