为什么不能解析这些变量？

Question

I need to write a program and, in one step of it, I need to construct a function that calculates the number of rabbits.

The problem is that Eclipse shows a message saying that the variable I created "cannot be resolved to a variable" and I don't understand why it happens. Can someone help me?

Here is part of my code

I am showing all my code because it would get bigger and it is not needed, in order to solve this problem

class Rabbits {
    static int nbRabbits = initRabbits;        // ERROR HERE!!!!!!!!!!!!!!!!!!!!!!!!!!
    static int nbFoxes = initFoxes;           // ERROR HERE!!!!!!!!!!!!!!!!!!!!!!!!!!
    int rabbits = 0;

    public static int calculateRabbits(int rabbits, int foxes, double AttackRate) {
        for (int i = 0; i < Duration; ++i) {
            rabbits = nbRabbits;
            nbRabbits *= (1.0 + Rabbits_growth_rate - AttackRate * nbFoxes);
        }
        return nbRabbits;
    }

    public static void main(String[] args) {
        Scanner keyb = new Scanner(System.in);

        // Enter initial population
        int initFoxes = enterPopulation("foxes", 2, keyb); //at least 2 foxes
        int initRabbits = enterPopulation("rabbits", 5, keyb); //at least 5 rabbits

        // SOME MORE CODE HERE
    }   // end main
} // end of class

initRabbits and initFoxes are variables entered by the user when I call enterPopulation method.

I'm new to Java and, unfortunately, I cannot change the logic of this code. For example, I cannot put the calculateRabbits method inside the main neither change the begin or the end of the code.

Answer 1

initRabbits only exists within the main method. That is it's scope .

You are attempting to statically reference something it can't see. You are attempting to populate nRabbits before a value for innitRabbits exists. This is impossible.

Answer 2

Your trying to assign a value to your nb variables from a variable that hasn't been created yet. Skip making four variables and just assign the nbs to 0 outside of your main class, then give them the value you want inside it. They will then retain that value outside of the main class and be visible.

static int nbRabbits = 0;
static int nbFoxes = 0;

//in main class
nbFoxes = enterPopulation("foxes", 2, keyb); //at least 2 foxes
nbRabbits = enterPopulation("rabbits", 5, keyb); //at least 5 rabbits