Why is this an issue?
Just as you can’t cut something into three halves, you can’t grab a substring that starts or ends outside the original
String's bounds, you can’t use substring to get a reversed portion of a String, and you can’t get the
charAt a value that’s before the String starts or after it ends.
This rule detects when negative literal or String::length is passed as an argument to the String::substring,
String::charAt and related methods.
Noncompliant code example
String speech = "Now is the time for all good people to come to the aid of their country.";
String substr1 = speech.substring(-1, speech.length()); // Noncompliant; start and end values both bad
String substr2 = speech.substring(speech.length(), 0); // Noncompliant, start value must be < end value
char ch = speech.charAt(speech.length()); // Noncompliant
Compliant solution
String speech = "Now is the time for all good people to come to the aid of their country.";
String substr1 = speech; // Closest correct values to original code yield whole string
String substr2 = new StringBuilder(speech).reverse().toString()
char ch = speech.charAt(speech.length()-1);
