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.
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
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);