Greenfoot

dave6969

2018/6/3

#

Hello, I am a begginer in coding and I want to make a parabolic simulation. I made the ball work. But the ask command keeps repeating once i type the answer. And I don't know how to get back an answer from the greenfoot.ask. Is it the return command and do I have to make another variable for the angle? And do I insert that into my public void act? Please help, its an easy project so it wont take long.

import greenfoot.*;  // (World, Actor, GreenfootImage, Greenfoot and MouseInfo)

public class ball extends Actor
{
    private double posx,posy,vx,vy,ax,ay,dt=0.1;
    
    public void addedToWorld(World myworld)
    {
       posx=getX(); 
       posy=getY();
       ax=0;
       ay=10;
       vx=20;
       vy=-20;
    }
    public void act() 
    {
        
        String input = Greenfoot.ask("What do you want the angle to be?");
        
        posx+=vx*dt+0.5*ax*dt*dt;
        posy+=vy*dt+0.5*ay*dt*dt;
        vx+=ax*dt;
        vy+=ay*dt;
        setLocation((int)posx,(int)posy);
        
    }    
}

danpost

2018/6/3

#

dave6969 wrote...

Hello, I am a begginer in coding and I want to make a parabolic simulation. I made the ball work. But the ask command keeps repeating once i type the answer. And I don't know how to get back an answer from the greenfoot.ask. Is it the return command and do I have to make another variable for the angle? And do I insert that into my public void act? Please help, its an easy project so it wont take long. << Code Omitted >>

Move line 19 to the addedToWorld method so it is only asked once.

dave6969

2018/6/3

#

danpost wrote...

dave6969 wrote...

Hello, I am a begginer in coding and I want to make a parabolic simulation. I made the ball work. But the ask command keeps repeating once i type the answer. And I don't know how to get back an answer from the greenfoot.ask. Is it the return command and do I have to make another variable for the angle? And do I insert that into my public void act? Please help, its an easy project so it wont take long. << Code Omitted >>

Move line 19 to the addedToWorld method so it is only asked once.

Thanks, and how do I make the answer to the question a variable and insert it into my code? Please help

danpost

2018/6/3

#

dave6969 wrote...

how do I make the answer to the question a variable and insert it into my code? Please help

Add a field to retain the variable:

private int angle;

and assign its value from the input:

angle = Integer.parseInt(input);

EDIT: you could make it a double field and use Double.parseDouble.

dave6969

2018/6/3

#

And if I want to have 2 questions and 2 answers do i do

 String input 2 = Greenfoot.ask("What do you want the angle to be?");

?

danpost

2018/6/3

#

dave6969 wrote...

And if I want to have 2 questions and 2 answers do i do << Code Omitted >> ?

Well, you would most probably change the question. If the questions are to be back-to-back, you can re-use input (so instead of

String input2 = ...

you could just use

input = ...

and parse it to the new field.

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