Java Operator Undefined Argument Type?

[Geralt]

Hey guys, I'm currently doing up a simple program in eclipse to take user input and output the data in a story with simple calculation involved (BMI)

import java.util.Scanner;public class InfoDisplay {	public static void main (String[] args) {				String name, nric, age, gender, weight, height, bmi;				Scanner in = new Scanner (System.in);				System.out.print("Enter Name: ");		name = in.nextLine();				System.out.print("Enter NRIC: ");		nric = in.nextLine();				System.out.print("Enter Age: ");		age = in.nextLine();				System.out.print("Enter Gender (Male/Female): ");		gender = in.nextLine();				System.out.print("Enter Weight: ");		weight = in.nextLine();				System.out.print("Enter Height: ");		height = in.nextLine();				bmi = ((weight * 703) /(height * height));				System.out.println("Hello! " + name);		System.out.println("Your NRIC is " + nric + "and age is" + age);		System.out.printf("Your Gender is " + gender + "and BMI is ");				in.close();	}}

The error:

The operator * is undefined for the argument type(s) String, int

Displays at the line

bmi = ((weight * 703) /(height * height));

What am I doing wrong? Previous java calculations work just fine when I type it out this way but not this time...

[,,,,,,,,,,,,,,,,,,,,,,,,,,]

Height is declared as a String, that may be your issue.

[Hominis]

You need to use Integer.parseInt() because you can't do math operations on Strings. Or you could do Double.parseDouble()

 

EDIT:

 

After looking at it again, there is no reason why age, height, or weight are String variable types. You should be able to use int, or double for them.

[Guest]

Strongly typed languages don't cast variables for you, you will need to do was the previous poster suggested.

[Speedyv]

import java.util.Scanner;

public class InfoDisplay {

public static void main (String[] args) {

 

 

Scanner in = new Scanner (System.in);

 

System.out.println("Enter Name: ");

String name = in.next();

 

System.out.println("Enter NRIC: ");

String nric = in.next();

 

System.out.println("Enter Age: ");

int age = in.nextInt();

 

System.out.println("Enter Gender (Male/Female): ");

String gender = in.next();

 

System.out.println("Enter Weight: ");

double weight = in.nextInt();

 

System.out.println("Enter Height: ");

double height = in.nextInt();

 

double bmi = ((weight * 703) /(height * height));

 

System.out.println("Hello! " + name);

System.out.println("Your NRIC is " + nric + "and age is " + age);

System.out.println("Your Gender is " + gender + "and BMI is " + bmi);

 

in.close();

}

}

[Hominis]

 

import java.util.Scanner;

public class InfoDisplay {

public static void main (String[] args) {

 

 

Scanner in = new Scanner (System.in);

 

System.out.println("Enter Name: ");

String name = in.next();

 

System.out.println("Enter NRIC: ");

String nric = in.next();

 

System.out.println("Enter Age: ");

int age = in.nextInt();

 

System.out.println("Enter Gender (Male/Female): ");

String gender = in.next();

 

System.out.println("Enter Weight: ");

double weight = in.nextInt();

 

System.out.println("Enter Height: ");

double height = in.nextInt();

 

double bmi = ((weight * 703) /(height * height));

 

System.out.println("Hello! " + name);

System.out.println("Your NRIC is " + nric + "and age is " + age);

System.out.println("Your Gender is " + gender + "and BMI is " + bmi);

 

in.close();

}

}

 

This is a good solution.

 

Although the last two output lines should be for readability:

 

System.out.println("Your NRIC is " + nric + " and age is " + age);

System.out.println("Your Gender is " + gender + " and BMI is " + bmi);

[Speedyv]

 

This is a good solution.

 

Although the last two output lines should be for readability:

 

System.out.println("Your NRIC is " + nric + " and age is " + age);

System.out.println("Your Gender is " + gender + " and BMI is " + bmi);

 

 

Oops don't know how I messed that up...

[Geralt]

Yep solved it after changing it to Double.parseDouble().

 

The declaration for each variable method seems a bit troublesome to me so I just prefer to declare it at the start rather than at each line.

 

Thanks all!

[MrSuperb]

Yep solved it after changing it to Double.parseDouble().

 

The declaration for each variable method seems a bit troublesome to me so I just prefer to declare it at the start rather than at each line.

 

Thanks all!

 

then do it at the top

import java.util.Scanner;public class InfoDisplay {	public static void main (String[] args) {			Scanner in;		String name, nric, gender;		double weight, height, bmi;		int age;		in = new Scanner (System.in);		 		System.out.println("Enter Name: ");		name = in.next();		 		System.out.println("Enter NRIC: ");		nric = in.next();		 		System.out.println("Enter Age: ");		age = in.nextInt();		 		System.out.println("Enter Gender (Male/Female): ");		gender = in.next();		 		System.out.println("Enter Weight: ");		weight = in.nextInt();		 		System.out.println("Enter Height: ");		height = in.nextInt();		 		bmi = ((weight * 703) /(height * height));		 		System.out.println("Hello! " + name);		System.out.println("Your NRIC is " + nric + "and age is " + age);		System.out.println("Your Gender is " + gender + "and BMI is " + bmi);		 		in.close();			}}

[Geralt]

 

then do it at the top

 

 

Yeap I always prefer to do it at the top in almost all of my school assignments.

 

[DavidTheWin]

Try to avoid splitting up your variable declaration and instantiation.

int number;// some other codenumber = in.nextInt();

Is not as clear or maintainable as

int number = in.nextInt();