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This noncompliant code example defines a method splitWords() that finds matches between the String literal and the input sequence. Because '\b' is the escape sequence for a word boundary, the misleading notion that String literals can be used as is, can convince the implementer that the pattern matches to the word boundaries and as a result, splits a given string into individual words. Instead, the string WORDS silently compiles to a backspace character.

import java.util.regex.Pattern;

public class BadSplitter {
  private final String WORDS = "\b"; // Intend to split on word boundaries

  public String[] splitWords(String input){
    Pattern p = Pattern.compile(WORDS);
    String[] input_array = p.split(input);
    return input_array;
  }
}

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This compliant solution shows the correctly escaped value of the String literal WORDS that results in a regular expression designed to split on word boundaries.

import java.util.regex.Pattern;

public class GoodSplitter {
  private final String WORDS = "\\b"; // Will allow splitting on word boundaries

  public String[] split(String input){
    Pattern p = Pattern.compile(WORDS);
    String[] input_array = p.split(input);
    return input_array;
  }
}

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