Description
Affects PMD Version: 6.18.0
Rule: StringToString
Description:
Attached code should help to understand better the following description.
We found a false-positive case for the rule String.toString().
When you assign an object field (of type String) to a field of another object (not of type String) calling toString(), the rule emits a warning about calling toString on a String object only when the field names match (value = otherObj.value.toString()). If either one of the field name changes, Pmd stops emitting the warning (workaround).
Since the enum is not a String object, we think that the warning is a false-positive triggered by the field name equality.
Code Sample demonstrating the issue:
See attached project for a ready-to-go reproduction case.
public enum AnEnum {
A,
B,
C;
}
public class AnEnumUser {
private final String value;
public AnEnumUser(final OtherEnumUser otherUser) {
// The following line triggers the "false-positive" warning
value = otherUser.value.toString();
}
public String getValue() {
return value;
}
}
public class OtherEnumUser {
public final AnEnum value;
public OtherEnumUser(final AnEnum value) {
this.value = value;
}
}
public final class Main {
private Main() {
}
public static void main(final String[] args) {
final OtherEnumUser a = new OtherEnumUser(AnEnum.A);
System.out.println("Original " + a.value);
final AnEnumUser aCopy = new AnEnumUser(a);
System.out.println("Copy " + aCopy.getValue());
}
}Running PMD through: Gradle