feed方法java if-statement

Question

decHungry() decreases hungry by 10 and incEnergy() increases energy by 10. I would like to make sure it does not go past 0 in hungry levels to negative numbers and does not go above 100 in energy levels. How do I do that?

protected void feed() {
    System.out.println("\nEating..."); 
    if (hungry <= 90 && hungry >= 0) {
        decHungry();
        incEnergy();
        System.out.println("I've just ate dumplings, my current energy state is " + energy + " and hungry state is " + hungry);
    }
    else { 
        System.out.println ("I have ate enough!"); 
    }
}

Answer 1

Before calling the function you want to make sure that hungry is greater than or equal to 10 and that energy is less than or equal to 90.

if(hungry >= 10){
    decHungry();
}
if(energy <=90){
    incEnergy();
}

Answer 2

The simplest way would probably be to add a check at the end to see if you went out of bounds, and if so return yourself to the bounds.

if(hungry<0)hungry=0;
if(energy>100)energy=100;

Answer 3

You should check for that after calling the methods decHungry and incEnergy . If the hungry or energy level exceeds the limits, then set them to the limit value:

protected void feed() {
    System.out.println("\nEating...");

    decHungry();
    incEnergy();

    if (hungry < 0)
        hungry = 0;

    if (energy > 100)
        energy = 100;

    // ...
}