package Mypoint;

class Point
{
    public int x;
    public int y;

    public void Point(int a,int b)
    {
        this.x=a;
        this.y=b;
    }
    public void display()
    {
        System.out.println("您创建了一个X坐标为："+x+",Y坐标为："+y+"的点("+x+","+y+")");
        System.out.println("--------------------------------");
    }
}





import java.util.Scanner;
class PointDemo
{
    public static void distance(Point a,Point b)
    {
        float m;
        m=(float) Math.sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
        System.out.println("这两个点之间的距离为："+m);
    }
    public static void main(String[] args)
    {
        System.out.println("本程序要实现的是计算两点之间的距离，点由用户来进行输入-----");
        Scanner A=new Scanner(System.in);
        Scanner B=new Scanner(System.in);
        Scanner C=new Scanner(System.in);
        Scanner D=new Scanner(System.in);

        
        System.out.println("请输入第1.个点:");
        int a,b;
        a=A.nextInt();
        b=B.nextInt();
        Point p1=new Point(a,b);
        p1.display();


        System.out.println("请输入第2.个点：");
        int c,d;
        c=C.nextInt();
        d=D.nextInt();
        Point p2=new Point(c,d);
        p2.display();


        distance(p1,p2);
    }

   
   
}

public class PointDemo
{
当然你没有贴出错提示先这么改吧

 public void Point(int a,int b)
{
    this.x=a;
    this.y=b;
}
这块应该是个构造方法，你写成了普通方法了（eclipse应该会有警告），去掉void试试看

 public Point(int a,int b)
{
    this.x=a;
    this.y=b;
}

表示新手

我才是一个纯新手！！！看不懂！

public void Point(int a,int b)
{
    this.x=a;
    this.y=b;
}
Point类的构造函数去掉void 就好了，修改之后如下
public  Point(int a,int b)
{
    this.x=a;
    this.y=b;
}