Java Error java.lang.StringIndexOutOfBoundsException: String index out of range: 0

Question

I'm receiving this exception along with these:

java.lang.StringIndexOutOfBoundsException: String index out of range: 0 at java.lang.String.charAt(Unknown Source) at RandomWalk.matchingChoice(RandomWalk.java:50) at RandomWalk.main(RandomWalk.java:17) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at edu.rice.cs.drjava.model.compiler.JavacCompiler.runCommand(JavacCompiler.java:267)

when running this code:

import java.util.*;
import java.awt.*;
public class RandomWalk{
  public static final Scanner CONSOLE = new Scanner(System.in);
  public static void main(String[] args){
    System.out.println("Enter Circle Radius (50-400):");
    int radius = CONSOLE.nextInt();
    while (radius < 50 || radius > 400){
      System.out.println("Radius Invalid; Try Again");
      System.out.println("Enter Circle Radius (50-400):");
      radius = CONSOLE.nextInt();
    }
    int diameter = radius*2;
    int panelD = diameter/4;
    System.out.println("Enter Color of Circle (Blue or Green)");
    String colorChoice = CONSOLE.nextLine();
    boolean test = matchingChoice(colorChoice, "blue");
    boolean test2 = matchingChoice(colorChoice, "green");
    while(test2 == false && test == false){
      System.out.println("Invalid Entry Try Again");
      System.out.println("Enter Color of Circle (Blue or Green)");
      colorChoice = CONSOLE.nextLine();
      test = matchingChoice(colorChoice, "blue");
      test2 = matchingChoice(colorChoice, "green");
    }
    if(test == true){
      Color circleColor = Color.BLUE;
    } else {
      Color circleColor = Color.GREEN;
    }
    System.out.println("Enter Color of Walk Path (Orange or Red)");
    colorChoice = CONSOLE.nextLine();
    test = matchingChoice(colorChoice, "orange");
    test2 = matchingChoice(colorChoice, "red");
    while(test2 == false && test == false){
      System.out.println("Invalid Entry Try Again");
      System.out.println("Enter Color of Circle (Orange or Red)");
      colorChoice = CONSOLE.nextLine();
      test = matchingChoice(colorChoice, "orange");
      test2 = matchingChoice(colorChoice, "red");
    }
    if(test == true){
      Color pathColor = Color.ORANGE;
    } else {
      Color pathColor = Color.RED;
    }
  }
  public static boolean matchingChoice(String input, String choice){
    input = input.toLowerCase();
    char fLI = input.charAt(0);
    char fLC = choice.charAt(0);
    if(fLI == fLC){
     return true;
    } else if (input.equals(choice)){
      return true;
    } else {
      return false;
    }
  }
}

the error comes just after

System.out.println("Enter Color of Circle (Blue or Green)");

I've attempted changing the nextLine to next and that would allow input but right after input the same error would appear. Any Help would be Much Appreciated, thank you.

Answer 1

you have make a mistake in CONSOLE.nextLine();, replace it like CONSOLE.next(); and your code will run correctly.

String colorChoice = CONSOLE.next();

replace all CONSOLE.nextLine() to CONSOLE.next()

Answer 2

Remove the final on your declaration of your Scanner:

public static final Scanner CONSOLE = new Scanner(System.in);

to

public static Scanner CONSOLE = new Scanner(System.in);

and then you will instantiate a new Scanner on your CONSOLE because you will input a different data type on your CONSOLE Variable .

System.out.println("Enter Color of Circle (Blue or Green)");
CONSOLE = new Scanner(); // Instantiate new Scanner on your CONSOLE variable
colorChoice = CONSOLE.nextLine();

hope it helps.