请教：什么原因Exception in thread "main" java.lang.NoSuchMethodError: Point.pointNum()I

Question

public class Example3_2 {
public static void main(String[] args) {
        Point p1,p2,p3;
    p1=new Point();
p2=new Point(40,50);
p3=new Point(p1.getX()+p2.getX(),p1.getY()+p2.getY());
System.out.println("P3.x="+p3.getX()+",p3.y="+p3.getY());
Point p4=new Point(p1.x,p2.y);
System.out.println("P4.x="+p4.x+",p4.y="+p4.y);
System.out.println("程序共有Point对象"+Point.pointNum()+"个");
}
}
class Point{
int x,y;
static int pCount=0;
Point(){
x=10;y=20;pCount++;
}
Point(int x,int y){
this.x=x;
this.y=y;
pCount++;
}
static int pointNum(){return pCount;}
int getX(){return x;}
int getY(){return y;}
}
编译时出现：“Exception in thread "main" java.lang.NoSuchMethodError: Point.pointNum()I”，什么原因？

Answer 1

Point.pointNum()I,后面有个I莫非代码中打错了吧