Integer literals should not start with zero since this denotes that the rest of literal will be interpreted as an octal value.

This rule reports exceptions thrown and caught in an enclosing try statement. This use of exceptions as a form of goto statement is discouraged, as that may hide actual exceptions, and obscures control flow, especially when debugging. To fix a violation, add the necessary validation or use an alternate control structure.

A high number of imports can indicate a high degree of coupling within an object. This rule counts the number of imports and reports a violation if the count is above the threshold. The default threshold above which a node is reported is 3.

Classes with large numbers of public methods and attributes require disproportionate testing efforts since combinational side effects grow rapidly and increase risk. The default threshold above which a node is reported is 2.

String.trim().length() == 0 and String.trim().isEmpty() are inefficient ways to check if a String is really blank. Prevent it.

Avoid instantiating String objects.

Assigning a null to a variable (outside of its declaration) is usually bad form.

Position literals first in all String comparison methods: non-overloaded 'boolean equals(Object o)' and 'equalsIgnoreCase' and 'compareTo' and 'compareToIgnoreCase' and 'contentEquals', if the second argument is null then NullPointerExceptions can be avoided, they will just return false.