Exercise02_15

 import javax.swing.JOptionPane;
 public class Distance {
     public static void main(String[] args){
         String number;
         double x1,x2,y1,y2,distance;
         number=JOptionPane.showInputDialog(null,"输入x1");
         x1=Double.parseDouble(number);
         number=JOptionPane.showInputDialog(null,"输入x2");
         x2=Double.parseDouble(number);
         number=JOptionPane.showInputDialog(null,"输入y1");
         y1=Double.parseDouble(number);
         number=JOptionPane.showInputDialog(null,"输入y2");
         y2=Double.parseDouble(number);
         distance=Math.pow((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1), 0.5);
         int messageType=JOptionPane.INFORMATION_MESSAGE;
         String message="The distance between the two points is " + distance;
         JOptionPane.showMessageDialog(null,message,"result",messageType);

     }
 }