I'm trying to understand why I'm receiving "String seems to be unrelated to String[]&-CodePudding

Im creating a project where the area or volume of certain shapes are calculated using dropdown menus in java. I don't have any errors when compiling however I'm getting the message that "Unlikely argument type for equals(): String seems to be unrelated to String[]". As stated, it complies fine, but when running it allows area/volume to be selected, but it does not reach the next option pane to select the shapes.

The message appears on: if (choices.equals("Area")) and : if (choices.equals("Volume"))

import javax.swing.JOptionPane;
public class Shapes 
{
    public static void main(String[] args)
    {

//Dropdown menu for area and volume
        String[] choices = {"Area", "Volume"};
        String question = (String) JOptionPane.showInputDialog(null, "What would you like to calculate?",
            "Shapes", JOptionPane.QUESTION_MESSAGE, null,
            choices,
            choices[0]);
        System.out.println(question);

        if (choices.equals("Area"))
        {
//user chooses area
            String[] choices2D = {"triangle", "parallelogram", "rectangle", "trapezoid", "circle"};
            String question2D = (String) JOptionPane.showInputDialog(null, "What shape will you choose?",
                "Shapes", JOptionPane.QUESTION_MESSAGE, null,
                choices2D,
                choices2D[0]);
            System.out.println(question2D);
        }
//user chooses volume
        if (choices.equals("Volume"))
        {
            String[] choices3D = {"cone", "cylinder", "rectanglular prism", "trapezoid prism", "sphere"};
            String question3D = (String) JOptionPane.showInputDialog(null, "What figure will you choose?",
                "Shapes", JOptionPane.QUESTION_MESSAGE, null,
                choices3D,
                choices3D[0]);
            System.out.println(question3D);
        }
    }
}

I originally had the options linked to a switch but would keep running into errors, after changing it to an if statement it will compile but not run properly.

CodePudding user response：

Your comparisons are choices.equals(…), but you meant to compare the selection from the dropbox, and this is stored in question. So the comparisons should be question.equals(…).

Alternatively, try this:

import javax.swing.JOptionPane;
public class Shapes 
{
    public static void main(String... args)
    {
        //Dropdown menu for area and volume
        String[] choices = {"Area", "Volume"};
        String question = (String) JOptionPane.showInputDialog( null, 
            "What would you like to calculate?",
            "Shapes", 
            JOptionPane.QUESTION_MESSAGE, 
            null,
            choices,
            choices[0]) ;
        System.out.println(question);

        switch( question )
        {
            case "Area":
            {
                //user chooses area
                String[] choices2D = {"triangle", "parallelogram", "rectangle", "trapezoid", "circle"};
                String question2D = (String) JOptionPane.showInputDialog( null,
                    "What shape will you choose?",
                    "Shapes", 
                    JOptionPane.QUESTION_MESSAGE, 
                    null,
                    choices2D,
                    choices2D[0] );
                System.out.println( question2D );
                break;
            }

            case "Volume":
            {
                //user chooses volume
                String[] choices3D = {"cone", "cylinder", "rectanglular prism", "trapezoid prism", "sphere"};
                String question3D = (String) JOptionPane.showInputDialog( null, 
                    "What figure will you choose?",
                    "Shapes", 
                    JOptionPane.QUESTION_MESSAGE, 
                    null,
                    choices3D,
                    choices3D[0] );
                System.out.println( question3D );
                break;
            }
        }
    }
}

You can also use the new switch-case syntax and optimise further, by using enums for the various choices.

CodePudding user response：

You are comparing the whole array with a single string. Use choices[0].equals("Area"). Now this will compare choices array with string at index 0 with Area.