Thread: my program for calculating the circumference and area isn't working

Here is the program I wrote for calculating the circumference of a circle

//circumference.java
//program that calculates the area and circumference of a circle

import java.util.Scanner; //program uses class scanner

public class circumference{

//main method begins execution of Java application

public static void main(String args[]){

//create scanner to obtain input from the command line

Scanner input = new Scanner(System.in);

double a; //declares Area
double c; //declares circumference

double r; //declares the radius

System.out.printf("Enter the radius"); //prompt
r=input.nextInt(); //read first number the user

c=2*3.14*r;

System.out.printf("The circumference is",c); //display circumference;

}//end method main

}//end class circumference

Even though my code compiles and runs without any errors, the program doesn't calculate the circumference.

Actually, I wanted to add when I add %d\n in the line of my code that displays the circumference, I get a large error message when I run the code.

--- Update ---

Here is what my code now looks like :"

//circumference.java
//program that calculates the area and circumference of a circle

import java.util.Scanner; //program uses class scanner

public class circumference{

//main method begins execution of Java application

public static void main(String args[]){

//create scanner to obtain input from the command line

Scanner input = new Scanner(System.in);

double a; //declares Area
double c; //declares circumference

double r; //declares the radius

System.out.print("Enter the radius"); //prompt
r=input.nextInt(); //read first number the user

c=2*3.14*r;

System.out.printf("The circumference is %d\n",c); //display circumference;

}//end method main

}//end class circumference

Even though my code compiles correctly, when I run it and it ask me to enter a value for the radius, I get a large error message. I can't displayed the error message here because the windows command line will not allow me to copy my error message

Welcome to the forum! Please read this topic to learn how to post code in code or highlight tags and other useful info for new members.

Please post your code in code tags per the above link.

Originally Posted by GregBrannon

Welcome to the forum! Please read this topic to learn how to post code in code or highlight tags and other useful info for new members.

Please post your code in code tags per the above link.

Okay I will repost my last post :


Actually, I wanted to add when I add %d\n in the line of my code that displays the circumference, I get a large error message when I run the code.

--- Update ---

Here is what my code now looks like :

 
//circumference.java
//program that calculates the area and circumference of a circle
 
import java.util.Scanner; //program uses class scanner
 
public class circumference{
 
//main method begins execution of Java application
 
public static void main(String args[]){
 
//create scanner to obtain input from the command line
 
Scanner input = new Scanner(System.in);
 
double a; //declares Area
double c; //declares circumference
 
double r; //declares the radius
 
System.out.print("Enter the radius"); //prompt
r=input.nextInt(); //read first number the user
 
c=2*3.14*r;
 
System.out.printf("The circumference is %d\n",c); //display circumference;
 
}//end method main
 
}//end class circumference

Even though my code compiles correctly, when I run it and it ask me to enter a value for the radius, I get a large error message. I can't displayed the error message here because the windows command line will not allow me to copy my error message

Thanks here is the output of my program after entered the radius:

Enter the radius8.90
Exception in thread "main" java.util.InputMismatchException
at java.util.Scanner.throwFor(Scanner.java:864)
at java.util.Scanner.next(Scanner.java:1485)
at java.util.Scanner.nextInt(Scanner.java:2117)
at java.util.Scanner.nextInt(Scanner.java:2076)
at circumference.main(circumference.java:22)
Press any key to continue . . .

Originally Posted by noblegas

Thanks here is the output of my program after entered the radius:

Read the error message. It clearly says "Input Mismatch", so there is something wrong with the way you retrieve input from the user.
Further down it tells us you use:

java.util.Scanner.nextInt()

But in the example you have shown us at the top you have inputted a double. That is clearly not compatible.

You are using the wrong formatter in the printf method. %d outputs integer types - not doubles.
Read up on the printf formatter types.

Thanks Ada, for coming back to life just to help me out with my java program error. What is the printf formatter type for a double?

What did you find when you Googled 'java formatter'?

When I google 'java formatter' the 1st website that pops up is oracle . (Formatter (Java Platform SE 7 ))

the formatter for 'double' is 'e' so I modify my code

Here is what my code looks like now :

/circumference.java
//program that calculates the area and circumference of a circle
 
import java.util.Scanner; //program uses class scanner
 
public class circumference{
 
	//main method begins execution of Java application
 
	public static void main(String args[]){
 
	//create scanner to obtain input from the command line
 
	Scanner input = new Scanner(System.in);
 
	double a; //declares Area
	double c; //declares circumferenceFunny How Time Slips Away
 
	double r; //declares the radius
 
	System.out.print("Enter the radius"); //prompt
	r=input.nextdouble(); //read first number the user
 
	c=2*3.14*r;
 
	System.out.printf("The circumference is %e\n",c); //display circumference;
 
}//end method main
 
}//end class circumference

the code still won't compile correctly. What did I do wrong?

What compiler errors are you getting? Always post error messages in their entirety that you want help with.