//This will make int random_terrain a random number between 0 and 100
int random_terrain = Greenfoot.getRandomNumber(100);

//And this will add that number of your terrain object
for(random_terrain = random_terrain; random_terrain > 0)
{
    addObject(new Object(), int x, int y);
    random_terrain--;
}

//This will make int random_terrain a random number between 0 and 100
int random_terrain = Greenfoot.getRandomNumber(100);

//And this will add that number of your terrain object
while (random_terrain > 0)
{
    addObject(new Object(), int x, int y);
    random_terrain--;
}

for( ; random_terrain > 0 ; random_terrain-- )
{
    addObject(new Object(), int x, int y);
}

int randomNumber = Greenfoot.getRandomNumber(FinalValue-InitialValue +1) + InitialValue;

int randomNumber = Greenfoot.getRandomNumber(121) -50;

int randomNumber = Greenfoot.getRandomNumber(21) +30;

int randomNumber = Greenfoot.getRandomNumber(51) -100;

int random = Greenfoot.getRandomNumber(50);
random = -random;