Exercise03_01

import javax.swing.JOptionPane;
public class TheDirection {
    public static void main(String[] args){
        double a,b,c,t,r1,r2;
        String number;
        int messageType=JOptionPane.INFORMATION_MESSAGE;
        number=JOptionPane.showInputDialog(null,"输入a"); 
        a=Double.parseDouble(number);
        number=JOptionPane.showInputDialog(null,"输入b"); 
        b=Double.parseDouble(number);
        number=JOptionPane.showInputDialog(null,"输入c"); 
        c=Double.parseDouble(number);
        t = b*b-4*a*c;
        if(t>0){
            r1 = (-b+Math.pow(t,0.5))/(2*a);
            r2 = (-b-Math.pow(t,0.5))/(2*a);
            String message="The equation has two roots " + r1 + " and "+ r2;
            JOptionPane.showMessageDialog(null,message,"result",messageType);
        }
        else if(t==0){
            r1 = (-b+Math.pow(t,0.5))/(2*a);
            String message="The equation has one roots " + r1;
            JOptionPane.showMessageDialog(null,message,"result",messageType);
        }
        else{
            String message="The equation has no real roots ";
            JOptionPane.showMessageDialog(null,message,"result",messageType);
        }
        
    }
}