Greenfoot

2021/9/30

Error: bad operand types for binary operator

2021/9/30

I have code where im trying to make it so a certain variation of the simulation runs depending on the temperature and i am getting an error with the if statements. These are in one of the worlds - beeWorld.

    public void runSimulation()
    {
        if(weatherValue >= -40 || weatherValue <= 15)
        {
            //if weatherValue is between -40 and 15 then run the low temperature simulation            
            lowTemperature();
        } else if(weatherValue >= 16 || weatherValue <= 25)
        {
            //if weatherValue is between 16 and 25 then run the regular temperature simulation            
            regularTemperature();
        } else if(weatherValue >= 26 || weatherValue <= 40)
        {
            //if weatherValue is between 26 and 40 then run the high temperature simulation            
            highTemperature();
        } else {
            //if values arent set, bring back the main menu
            Greenfoot.setWorld(new mainMenu());
        }
    }

i have weatherValue defined in the code aswell as this:

    weatherInput weatherValue;

Does anyone know how to fix this error?

MrBradley

2021/9/30

Can you provide the definition of weatherInput? Generally, you cannot use relational operators (>=, <, etc.) with your own types. They are only defined for numeric primitives (int, double, etc). Also, it is always useful to provide the error you are getting.

xixEmilyxix

2021/9/30

public class weatherInput extends Actor
{
    //create variable
    int weatherValue;
    /**
     * Act - do whatever the weatherInput wants to do. This method is called whenever
     * the 'Act' or 'Run' button gets pressed in the environment.
     */
    public void act() 
    {
      //Create input box, ask for value, set bounds for weatherValue
      setImage(new GreenfootImage("Input.png"));
      
      //show weatherValue in the box on main menu
      getWorld().showText("" + weatherValue, 400, 250);
      
      //show weatherValue in the box on the main simulation screen
      getWorld().showText("" + weatherValue, 400, 250);
      
      //set value of weather based off the input
        if(Greenfoot.mouseClicked(this))
        {
            weatherValue = Integer.parseInt(Greenfoot.ask("Please input a value for the weather"));
        if(weatherValue < -40 || weatherValue > 40)
        {
            World world = getWorld();
            world.addObject(new errorMessageweather(), 350, 200);
        } else {
            World world = getWorld();
            world.removeObjects(world.getObjects(errorMessageweather.class));
        } 
      }
    }
}

this is the code i have in my weatherinput class

xixEmilyxix

2021/9/30

the error is: bad operand types for binary operator '>=' first type: weatherInput second type: int

danpost

2021/10/1

xixEmilyxix wrote...

the error is: bad operand types for binary operator '>=' first type: weatherInput second type: int

You have weatherValue defined as a weatherInput object in your beeWorld. The value of weatherValue held by your weatherInput object would then be:

int wv = weatherValue.weatherValue;

You should probably define the object in beeWorld with:

weatherInput wi;

and then use:

int wv = wi.weatherValue;

in the method of beeWorld.

danpost

2021/10/1

By convention, class names should begin with an uppercase letter (BeeWorld, WeatherInput, etc.) and field names with a lowercase letter (weatherValue). Then you can declare the object in BeeWorld with:

WeatherInput weatherInput;

and use the following within the method:

int weatherValue = weatherInput.weatherValue;

(the weatherInput field should be assigned a WeatherInput object prior to using code in method -- assigned either in the constructor of your BeeWorld or in the declaration line) That way, when you see something beginning with an uppercase letter, it will probably be a class name and when you see something beginning with a lowercase letter, it will probably be a field name (you can keep then identifiable that way).

xixEmilyxix

2021/10/6

Thank you, and especially for the tip I changed those over :D

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Error: bad operand types for binary operator