title: Java: StringIndexOutOfBoundsException
body: <p>I'm getting StringIndexOutOfBoundsException:</p>
  
  <blockquote>
    <p>Exception in thread "main" java.lang.StringIndexOutOfBoundsException: begin 3, end 4, length 3
        at java.base/java.lang.String.checkBoundsBeginEnd(String.java:3116)
        at java.base/java.lang.String.substring(String.java:1885)
        at ReadZILLA.main(Main.java:26)</p>
  </blockquote>
  
  <p>from the following code:</p>
  
  <pre><code>import java.io.*;
  import java.text.*;
  
  class ReadZILLA {
  
  public static void main(String[] args) throws IOException {
      int vowel = 0;
      int words = 0;
      int line = 10;
      int line_no = 11-line;
      int n = 1;
      String a = "a";
      String e = "e";
      String i = "i";
      String o = "o";
      String u = "u";
      String A = "A";
      String E = "E";
      String I = "I";
      String O = "O";
      String U = "U";
      String space = " ";
      BufferedReader in_text = new BufferedReader(new InputStreamReader(System.in));
      String text = in_text.readLine();
  
      while(line &gt; 1){
          String char_def = text.substring(n-1,n);
          System.out.println(char_def);
  
          if (char_def == a || char_def == e || char_def == i || char_def == o || char_def == u || char_def == A || char_def == E || char_def == I|| char_def == O || char_def == U){
              vowel = vowel + 1;
          } else if (char_def == space){
              words = words +1;
          } else if (char_def == "\n"){
              System.out.println ("Numbers of vowels: " + vowel + "in line " + line_no);
              vowel = 0;
              line = line-1;
  
          }
  
          n = n +1;
  
      }
  
      int words_avg = words/10;
      System.out.println("Number of words: " + words);
      System.out.println("Average number of words: " + words_avg);
  
  }
  </code></pre>
  
  <p>The program is called ReadZILLA and it's supposed to output the numbers of vowels, words and average words in a line from the input.
  E.G input: tHe DoG is BrOWN /n thE cat IS rED
  output: vowels: 8, words: 8, average words per line: 4</p>