Greenfoot

manster2008 wrote ...

2011/6/20

How to recognize left-clicking even if the mosue isn't moving...

manster2008

2011/6/20

For my code...

MouseInfo m = getWorld().getMouseInfo();
if(m != null && m.getButton() == 1) {
     instructions...
     instructions...
     instructions...
}

I use this. The problem is though, that since I have used the if(m != null) {}, If I don't move the mouse and click, it will only do the instructions 2 times, one for clicking, and one for letting go of my finger... how do I do it so that it does the instructions infinitely even if the mouse is not being moved when clicked? Thanks...

Busch2207

2011/6/20

Use this Code:

if(Greenfoot.mouseClicked(null))
{
MouseInfo M = Greenfoot.getMouseInfo();
if(M.getButton()==1)
{
[...]
}
}

davmac

2011/6/20

If I understand the question right, you want to keep doing something while the mouse button is down? Just track the button state in a separate instance variable. Inside your class (outside the method!), declare an instance variable as follows:

// Declare an instance variable:
private boolean mouseButtonDown;

Then change your existing code to:

MouseInfo m = getWorld().getMouseInfo();
if(m != null) {
    mouseButtonDown = (m.getButton() == 1);
}

if (mouseButtonDown) {
     instructions...
     instructions...
     instructions...
}

manster2008

2011/6/23

First of all, davmac, you're a genius. Second, sorry for typing mouse wrong I was trying to type quickly. Would your code be the same as the following?

MouseInfo m = getWorld().getMouseInfo();  
if(m != null && m.getButton() == 1) {  
    mouseButtonDown = true;
}  
  
if (mouseButtonDown) {  
     instructions...  
     instructions...  
     instructions...  
}

manster2008

2011/6/23

Correction: There also has to be an else "mouseButtonDown = false;".

davmac

2011/6/23

Thankyou, I don't get called a genius everyday! That's right, there also has to be an else "mouseButtonDown = false"; I think you would need to write it something like this:

MouseInfo m = getWorld().getMouseInfo();  
if(m != null) {
    if (m.getButton() == 1) {  
        mouseButtonDown = true;
    }
    else {
        mouseButtonDown = false;
    }
}  
  
if (mouseButtonDown) {  
     instructions...  
     instructions...  
     instructions...  
}

manster2008

2011/6/23

I have one more problem... I am making this game where a rocket starts in the middle of a grid, and it's location is 0, 0. There are three different planets in different locations, such as -1, 0 & 5, 2 & etc. What I would like to do is set a random location for all 3 planets. I have done so like this. For the following code, p stands for planet.

p1x = Greenfoot.getRandomNumber(21) - 9;
if(p1x < 1) {
    p1x--;
}
p1y = Greenfoot.getRandomNumber(21) - 9;
if(p1y < 1) {
    p1y--;
}
p2x = Greenfoot.getRandomNumber(21) - 9;
if(p2x < 1) {
    p2x--;
}

& so on.... Instead of this... I want to set up a public void randomInt(String varname) {} So all I have to do is put the name of my variable in the method, and a random number between -10 & 10, not counting 0, is entered into the variable. The problem is, how do I de-string the String varname so that I can do the follozing?:

varname = Greenfoot.getRandomNumber(20) - 9;
        if(varname < 1) {
            varname--;
        }

davmac

2011/6/24

You can't do that exactly in Java. You have a few options: First option: store the values in a HashMap eg:

public void randomInt(HashMap<String,Integer> varMap, String varname)
{
    int var = Greenfoot.getRandomNumber(20) - 9;
    if (var < 1) {
        var--;
    }
    varMap.put(varname, var);
}

For this to work you'll need to import the HashMap class at the top of your class:

import java.util.HashMap;

You'll also have to create a new map (new HashMap<String,Integer>()) and pass it to the randomInt method. Replace your code above with:

HashMap<String,Integer> varMap = new HashMap<String,Integer>();
randomInt(varMap, "p1x");
randomInt(varMap, "p1y";
randomInt(varMap, "p2x";
...

To get values out of the map, use "hashmap.get(varname)" (where "varname" is a String). Second option: use an array:

int [] planetCoords = new int[6];  // 3 x and 3 y coordinates
for (int i = 0; i < 6; i++) {
   randomInt(planetCoords, i);
}

and

public void randomInt(int [] array, int index)
{
    int var = Greenfoot.getRandomNumber(20) - 9;
    if (var < 1) {
        var--;
    }
    array[index] = var;
}

Now the p1x value is planetCoords, p1y is planetCoords, p2x is planetCoords, etc. There are other possibilities, but this should get you started!

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How to recognize left-clicking even if the mosue isn't moving...