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PiledroMurcia
Asked: 2020-05-24 02:27:57 +0800 CST 2020-05-24 02:27:57 +0800 CST

Randomize Random

  • 772

In my method I have a Random variable:

   public Bitmap getBmp(int nunidades,boolean base){
    Bitmap bmp = Bitmap.createBitmap(ladoWidth * nunidades, ladoHeight, Bitmap.Config.ARGB_8888);
    Canvas canvas = new Canvas(bmp);
    int nbase = 0;
    int nespacio = 0;
    if(base){
        if(baseinicial != null){
            canvas.drawBitmap(baseinicial,0,0,null);
            nbase = 1;
        }
        for(;nbase < nunidades;nbase++){
            canvas.drawBitmap(baserepeticion,nbase*ladoWidth,0,null);
        }
    }else {
        //adornos
        if(!type.equalsIgnoreCase("Columnas")){
            int random = rnd.nextInt(adornos.size());
            ObjetoAdorno obj = new ObjetoAdorno(adornos.get(random).getTiles());
            ObjetoAdorno objf = new ObjetoAdorno();
            objf.setAdornos(obj.getAdornos());
            int tile = obj.getnAdornos();
            Log.d(GLOBALES.TAG,"espacio="+nunidades);
            Log.d(GLOBALES.TAG,"random="+random);
            Log.d(GLOBALES.TAG,"tile="+tile);
            if(nunidades> tile){
                Log.d(GLOBALES.TAG,"hay espacio");
                for(;nespacio < nunidades;nespacio++){
                    baseadornos.add(baserepeticion);
                    if(tile > 1){
                        for(int i=0;i<tile;i++){
                            baseadornos.add(objf.getAdornos().get(i));
                        }
                    }else{
                        baseadornos.add(objf.getAdornos().get(0));
                    }
                }
            }else{
                Log.d(GLOBALES.TAG,"No hay espacio");
                for(;nespacio < nunidades;nespacio++){
                    baseadornos.add(baserepeticion);
                }
            }
        }else{
            for(;nbase < nunidades;nbase++){
                baseadornos.add(baserepeticion);
            }
        }
        for(int i=0;i < nunidades;i++){
            canvas.drawBitmap(baseadornos.get(i),i*ladoWidth,0,null);
        }
    }
    return bmp;
}

The problem is that the value of random is always the same

java

4 Answers

  1. Best Answer

    Check the size of your collection adornos:

    int random = rnd.nextInt(adornos.size());

    The problem is that if the size()number of decorations is very small, for example 1, the only value that will be returned is 0 (1 is excluded).

    If, for example, there were 2 ornaments, it would return 0 and 1, and if you haven't done enough testing, it can make you believe that it always returns the same result.

    Here is some information on how it works that might help you: random .nextInt(n)

    • 3

  2. From java 1.7 onwards you can use,

    int randomNum = ThreadLocalRandom.current().nextInt(0, adornos.size()+ 1);

    ThreadLocalRandombelongs to the packagejava.util.concurrent.ThreadLocalRandom;

    For versions prior to java 1.7

    int randomNum = new Random().nextInt((adornos.size() - 0) + 1) + 0;

    Extracted from this post

    • 1

  3. You Randomdon't seem to have any problem, possibly it's a coincidence that you always get the same one. Every time you call the method getBmpa new Random:

    Random rnd = new Random();
int max = 10; //Número máximo aleatorio que puede salir
int min = 1; //Número mínimo aleatorio que puede salir
int aleatorio = rnd.nextInt(max - min + 1) + min;
    • 1

  4. The problem is that the value of random is always the same

    Random rnd = new Random();
int random = rnd.nextInt(adornos.size());

    The only explanation is that the value of the measure of the decorations array is 1, for this reason a value is always obtained.

    You can perform a test for example if you define that the value of ornaments.size() is 10 and print the value, you will get random numbers from 0 to 9:

    Random rnd = new Random();
for(int i =0; i< 100;i++) {
    int random = rnd.nextInt(10);
    Log.i(TAG, "valor random: " +  random);
}
    • 0