How do I fix my "java.util.InputMismatchException" error? -
all need loop again user can continuously use program if to. let me know if there reference can read to, me understand more problem. in advance.
import java.util.scanner; public class module3assignment1 { // public variables public static string letterchosen; public static int loop = 0; public static double radius, area; public static scanner scanner = new scanner(system.in); public static void main(string[] args) { // tells user program system.out.println("welcome round object calculator"); system.out.println("this program calculate area of circle of colume of sphere."); system.out.println("the calculations based on user input radius."); system.out.println(""); // loops while user wants calculate information while (loop == 0){ input(); system.out.print(answer()); system.out.println("do want calculate round object (y/n)? "); string input = scanner.next().touppercase(); if (input == "n"){ loop = 1; } } // ending message/goodbye goodbye(); scanner.close(); } private static void input(){ // prompts user input system.out.print("enter c circle or s sphere: "); letterchosen = scanner.nextline().touppercase(); system.out.print("thank you. radius of circle (in inches): "); radius = scanner.nextdouble(); } private static double areacircle(){ // calculates area of circle area = math.pi * math.pow(radius, 2); return area; } private static double areasphere(){ // calculates area of sphere area = (4/3) * (math.pi * math.pow(radius, 3)); return area; } private static string answer(){ //local variables string answer; if(letterchosen == "c"){ // builds string circle answer , sends answer = string.format("%s %f %s %.3f %s %n", "the volume of circle radius of", radius, "inches is:", areacircle(), "inches"); return answer; }else{ // builds string sphere answer , sends answer = string.format("%s %f %s %.3f %s %n", "the volume of sphere radius of", radius, "inches is:", areasphere(), "cubic inches"); return answer; } } private static string goodbye(){ // local variables string goodbye; // says , returns goodbye message goodbye = string.format("%s", "thank using round object calculator. goodbye"); return goodbye; } } the below console output , error getting after execution
welcome round object calculator program calculate area of circle of colume of sphere. calculations based on user input radius. enter c circle or s sphere: c thank you. radius of circle (in inches): 12 volume of sphere radius of 12.000000 inches is: 5428.672 cubic inches want calculate round object (y/n)? y enter c circle or s sphere: thank you. radius of circle (in inches): c exception in thread "main" java.util.inputmismatchexception @ java.util.scanner.throwfor(scanner.java:840) @ java.util.scanner.next(scanner.java:1461) @ java.util.scanner.nextdouble(scanner.java:2387) @ module3assignment1.input(module3assignment1.java:48) @ module3assignment1.main(module3assignment1.java:24)
import java.util.scanner; public class module3assignment1 { // public static variables discouraged... private static char letterchosen; //char takes less memory private static char useagain = 'y'; //just use answer loop... private static double radius, area; private static string answer; private static scanner scanner = new scanner(system.in); //you might want clear screen after user gave answer round object private static void clearscreen(){ for(int =0;i<50;i++){system.out.print("\n");} } public void input(){ // prompts user input system.out.print("enter c circle or s sphere: "); letterchosen = scanner.next().charat(0); system.out.print("thank you. radius of circle (in inches): "); radius = scanner.nextdouble(); this.answer= answer(letterchosen); } public double areacircle(double radius){ // calculates area of circle area = math.pi * math.pow(radius, 2); return area; } public double areasphere(double radius){ // calculates area of sphere area = (4/3) * (math.pi * math.pow(radius, 3)); return area; } public string answer(char letterchosen){ //local variables string answer = ""; if(letterchosen=='c'||letterchosen=='c'){ answer = string.format("%s %f %s %.3f %s %n", "the volume of circle radius of", radius, "inches is:", areacircle(radius), "inches"); }else{ answer = string.format("%s %f %s %.3f %s %n", "the volume of sphere radius of", radius, "inches is:", areasphere(radius), "cubic inches"); } return answer; } private static string goodbye(){ // local variables string goodbye; // says , returns goodbye message goodbye = string.format("%s", "thank using round object calculator. goodbye"); return goodbye; } public static void main(string[] args) { // tells user program system.out.println("welcome round object calculator"); system.out.println("this program calculate area of circle of colume of sphere."); system.out.println("the calculations based on user input radius."); system.out.println(""); module3assignment1 ass1 = new module3assignment1(); // loops while user wants calculate round object while (useagain == 'y'||useagain=='y'){ ass1.input(); system.out.print(answer); system.out.println("do want calculate round object (y/n)? "); useagain = scanner.next().charat(0); system.out.println(useagain); clearscreen(); } // ending message/goodbye system.out.println(goodbye()); scanner.close(); } }
some things changed:
- i used char instead of string. string takes more memory char.
- added clearscreen() method "clears" screen when you're using console.
i added parameter radius areasphere , areacircle methods. makes methods reusable.
i changed public static variables private static. using public static variables highly discouraged. may read this find out why.
and prevent public static variables, created instance of module3assignment1 instead of having in static.
changed casing of method names. please follow camel-casing, means first letter of method lowercase , other words have first letter in uppercase (e.g. input(), areasphere() )
a comment comparing strings:
== compares references object , not values
use .equals() or .equalsignorecase() if want compare values of 2 strings. here sample syntax:
if(string1.equals(string2)){ //do } 
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