java.lang.ArrayIndexOutOfBoundsException 和 If 逗号后面的条目不是整数

Question

我的代码中不断收到错误:java.lang.ArrayIndexOutOfBoundsException: 1。这是我学习 java 的第一个学期，所以任何帮助将不胜感激。还有，一石二鸟。我的 if 语句之一遇到问题。

如果逗号后面的条目不是整数:

输出:“错误:逗号后面没有跟整数。”

提前致谢。

import java.util.Scanner;
import java.util.ArrayList;
import java.io.PrintWriter;
import java.io.StringWriter;

public class DataVisualizer {
   public static void main(String[] args) {
      Scanner input = new Scanner(System.in);      
      Scanner inSS = null;
      String title = "";
      String column1header = "";
      String column2header = "";
      String dataString = "";
      String dataPoint = "";
      String dataInt = "";
      boolean inputDone = false;
      char comma = ',';

      System.out.println("Enter a title for the data: ");
      title = input.nextLine();

      System.out.println("You entered: " + title);
      System.out.println("");

      System.out.println("Enter the column 1 header: ");
      column1header = input.nextLine();

      System.out.println("You entered: " + column1header);
      System.out.println("");

      System.out.println("Enter the column 2 header: ");
      column2header = input.nextLine();

      System.out.println("You entered: " + column2header);
      System.out.println("");

      ArrayList<String> string = new ArrayList<String>();
      ArrayList<Integer> integer = new ArrayList<Integer>();

      System.out.println("Enter a data point (-1 to stop input): ");     

      while (!inputDone) {

          dataPoint = input.nextLine();
          inSS = new Scanner(dataPoint);

          if (dataPoint.equals("-1")) {
              inputDone = true;
              break;
          }

          if (!dataPoint.contains(",")) {
              System.out.println("Error: No comma in string.");

          }

 // Here is the problem I am running with my if statement.            

          if (dataPoint.indexOf(",") != dataPoint.lastIndexOf(",")) {
              System.out.println("Error: Too many commas in input.");

          }

          if (Character.isDigit(dataPoint.charAt(-1))) {
              System.out.println("Error: Comma not followed by an integer.");
              System.out.println("");
              System.out.println("Enter a data point (-1 to stop input): ");
          }


          else {

// This is where Im getting my error              

              String[] items = dataPoint.split(",");

              for (int i = 0; i < items.length; ++i){
                  dataString = items[0];
                  dataInt = items[1];
                }

              Integer dataInteger = Integer.valueOf(dataInt);
              System.out.println("Data string: " + dataString);

              System.out.println("Data integer: " + dataInteger);

              string.add(dataString);
              integer.add(dataInteger);
            }   
            System.out.println("");
            System.out.println("Enter a data point (-1 to stop input): ");

      }
      return;
   }     
}

Answer 1

您试图获取索引-1处的字符，在这里您将得到StringIndexOutOfBoundsException

Character.isDigit(dataPoint.charAt(-1))

索引应该在0到string.length()-1之间