gyrodraw/GyroDraw

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)

Before Java 8, the only way to partially support closures in Java was by using anonymous inner classes. But the syntax of anonymous classes may seem unwieldy and unclear.

With Java 8, most uses of anonymous inner classes should be replaced by lambdas to highly increase the readability of the source code.

Note that this rule is automatically disabled when the project's sonar.java.source is lower than 8.

Noncompliant Code Example

myCollection.stream().map(new Mapper<String,String>() {
  public String map(String input) {
    return new StringBuilder(input).reverse().toString();
  }
});

Predicate<String> isEmpty = new Predicate<String> {
    boolean test(String myString) {
        return myString.isEmpty();
    }
}

Compliant Solution

myCollection.stream().map(input -> new StringBuilder(input).reverse().toString());

Predicate<String> isEmpty = myString -> myString.isEmpty();