第五題

import java.io.*;
import java.awt.geom.Point2D;
public class KeyIn {
public static void main(String[] args) throws IOException {
BufferedReader keyin;
keyin = new BufferedReader(new InputStreamReader(System.in));
double p1a, p1b, p2a, p2b, p3a, p3b;
System.out.println("keyin p1a： ");
String n1 = keyin.readLine();
p1a = Double.parseDouble(n1);
System.out.println("keyin p1b： ");
String e1 = keyin.readLine();
p1b = Double.parseDouble(e1);
System.out.println("keyin p2a： ");
String n2 = keyin.readLine();
p2a = Double.parseDouble(n2);
System.out.println("keyin p2b： ");
String e2 = keyin.readLine();
p2b = Double.parseDouble(e2);
System.out.println("keyin p3a： ");
String n3 = keyin.readLine();
p3a = Double.parseDouble(n3);
System.out.println("keyin p3b： ");
String e3 = keyin.readLine();
p3b = Double.parseDouble(e3);

Point2D.Double p1 = new Point2D.Double(p1a, p1b);
Point2D.Double p2 = new Point2D.Double(p2a, p2b);
Point2D.Double p3 = new Point2D.Double(p3a, p3b);

System.out.println("P1到P2的距離: " + p1.distance(p2));
System.out.println("P2到P3的距離: " + p2.distance(p3));

}
}