Most checks against an indexOf value compare it with -1 because 0 is a valid index. Any checks which look for values >0 ignore the first element, which is likely a bug. If the intent is merely to check inclusion of a value in a String or a List, consider using the contains method instead.

For strings, if the intent is truly to find the first index after a specific character index, then use the version of indexOf which takes a start position argument.

This rule raises an issue any time an indexOf value retrieved either from a String or a List is tested for a positive value.

Noncompliant Code Example

String color = "blue";
String name = "ishmael";

List<String> strings = new ArrayList<String>();
strings.add(color);
strings.add(name);

if (strings.indexOf(color) > 0) {  // Noncompliant
  // ...
}
if (name.indexOf("ish") > 0) { // Noncompliant
  // ...
}
if (name.indexOf("hma") > 2) { // Noncompliant
  // ...
}

Compliant Solution

String color = "blue";
String name = "ishmael";

List<String> strings = new ArrayList<String>();
strings.add(color);
strings.add(name);

if (strings.indexOf(color) > -1) {
  // ...
}
if (name.indexOf("ish") >= 0) {
  // ...
}
if (name.indexOf("hma") > -1) {
  // ...
}