Add a private constructor to hide the implicit public one. Open
public class ModelFactory {
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- Exclude checks
Utility classes, which are collections of static
members, are not meant to be instantiated. Even abstract utility classes, which can
be extended, should not have public constructors.
Java adds an implicit public constructor to every class which does not define at least one explicitly. Hence, at least one non-public constructor should be defined.
Noncompliant Code Example
class StringUtils { // Noncompliant public static String concatenate(String s1, String s2) { return s1 + s2; } }
Compliant Solution
class StringUtils { // Compliant private StringUtils() { throw new IllegalStateException("Utility class"); } public static String concatenate(String s1, String s2) { return s1 + s2; } }
Exceptions
When class contains public static void main(String[] args)
method it is not considered as utility class and will be ignored by this
rule.
Catch Exception instead of Throwable. Open
} catch (Throwable e) {
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Throwable
is the superclass of all errors and exceptions in Java. Error
is the superclass of all errors, which are not
meant to be caught by applications.
Catching either Throwable
or Error
will also catch OutOfMemoryError
and InternalError
, from
which an application should not attempt to recover.
Noncompliant Code Example
try { /* ... */ } catch (Throwable t) { /* ... */ } try { /* ... */ } catch (Error e) { /* ... */ }
Compliant Solution
try { /* ... */ } catch (RuntimeException e) { /* ... */ } try { /* ... */ } catch (MyException e) { /* ... */ }
See
- MITRE, CWE-396 - Declaration of Catch for Generic Exception
- C++ Core Guidelines E.14 - Use purpose-designed user-defined types as exceptions (not built-in types)