Java中的算术异常，如何处理？

Question

I'm making a program that counts the frequency of letters from a user-entered string, and have recently encountered the 'Arithmetic Exception' error.

I cannot for the life of me figure out what's causing it, even though I know it's because something is being divided by 0.

Here's my code:

package day1.examples;

import java.util.Scanner;

public class rl_frequency_count {

    public static int input;

    public static void main(String[] args) {

        System.out
                .println("Please enter some text that you would like to work out the occurence for.");
        System.out
                .println("However, do remember that any other characters outside of the alphabet will NOT be counted.");

        Scanner stringUser = new Scanner(System.in);
        String input = stringUser.nextLine();
        input = input.replaceAll("\\s+", "");
        input = input.toLowerCase();

        // counting occurrence of character with loop
        int i;
        int charCountA = 0;
        int charCountB = 0;
        int charCountC = 0;
        int charCountD = 0;
        int charCountE = 0;
        int charCountF = 0;
        int charCountG = 0;
        int charCountH = 0;
        int charCountI = 0;
        int charCountJ = 0;
        int charCountK = 0;
        int charCountL = 0;
        int charCountM = 0;
        int charCountN = 0;
        int charCountO = 0;

        for (i = 0; i < input.length(); i++) {
            if (input.charAt(i) == 'a') {
                charCountA++;
                getOccurence(charCountA, "A");
            }
        }
        for (i = 0; i < input.length(); i++) {
            if (input.charAt(i) == 'b') {
                charCountB++;
                getOccurence(charCountB, "B");
            }
        }
        for (i = 0; i < input.length(); i++) {
            if (input.charAt(i) == 'c') {
                charCountC++;
                getOccurence(charCountC, "C");
            }
        }
        for (i = 0; i < input.length(); i++) {
            if (input.charAt(i) == 'm') {
                charCountM++;
                getOccurence(charCountM, "M");
            }
        }
    }

    // method for the occurrence
    public static void getOccurence(int number, String letter) {
        double occ = number / input * 10; //
        System.out.println();
        System.out.println("Number of " + letter + "'s - " + number);
        System.out.println("Occurence of " + letter + " - " + occ + "%");
    }
}

I know that I only have ABC and M in at the moment but was gonna work those in later.

This is the first time i've posted on here and i'm still newish to Java so any help whatsoever is greatly appreciated!

Answer 1

I ran it and it says line 67. here is the total:

public static void getOccurence(int number,String letter){
    double occ = number / input *10; //
    System.out.println();
    System.out.println("Number of "+ letter +"'s - "+ number);
    System.out.println("Occurence of "+ letter +" - "+ occ + "%");
}

To fix:

  double occ = (number > 0) ? number/input * 10 : 0;

This sets occ to 0 in case of number being set to 0. Good luck. Hope this helps.

Answer 2

The line of code causing the error is in your method:

public static void getOccurence(int number,String letter){ 
    double occ = number / input *10; // <------ERROR FROM HERE (input is always 0)
    System.out.println();
    System.out.println("Number of "+ letter +"'s - "+ number);
    System.out.println("Occurence of "+ letter +" - "+ occ + "%");       
  }

The input variable is declared in your class here:

Line 6: public static int input;

Since you didn't initialize it nor does the value is being changed in your codes, the value of input remains as 0 through out the entire program. (Default value for an uninitialized int variable is 0)

Since it is always 0, you are always dividing a number with 0.

double occ = number / 0*10;