The Basic Ruleset contains a collection of good practices which everyone should follow. Empty Catch Block finds instances where an exception is caught, but nothing is done. In most circumstances, this swallows an exception which should either be acted on or reported. 3 false Empty If Statement finds instances where a condition is checked but nothing is done about it. 3 Empty While Statement finds all instances where a while statement does nothing. If it is a timing loop, then you should use Thread.sleep() for it; if it's a while loop that does a lot in the exit expression, rewrite it to make it clearer. 3 Avoid empty try blocks - what's the point? 3 Avoid empty finally blocks - these can be deleted. 3 Avoid empty switch statements. 3 Avoid jumbled loop incrementers - it's usually a mistake, and it's confusing even if it's what's intended. 3 Some for loops can be simplified to while loops - this makes them more concise. 3 1] [not(ForInit)] [not(ForUpdate)] [not(Type and Expression and Statement)] ]]> Avoid unnecessary temporaries when converting primitives to Strings 3 Override both public boolean Object.equals(Object other), and public int Object.hashCode(), or override neither. Even if you are inheriting a hashCode() from a parent class, consider implementing hashCode and explicitly delegating to your superclass. 3 Partially created objects can be returned by the Double Checked Locking pattern when used in Java. An optimizing JRE may assign a reference to the baz variable before it creates the object the reference is intended to point to. For more details see http://www.javaworld.com/javaworld/jw-02-2001/jw-0209-double.html. 1 Avoid returning from a finally block - this can discard exceptions. 3 Avoid empty synchronized blocks - they're useless. 3 Avoid unnecessary return statements 3 An empty static initializer was found. 3 Do not use "if" statements that are always true or always false. 3 An empty statement (aka a semicolon by itself) that is not used as the sole body of a for loop or while loop is probably a bug. It could also be a double semicolon, which is useless and should be removed. 3 Avoid instantiating Boolean objects; you can reference Boolean.TRUE, Boolean.FALSE, or call Boolean.valueOf() instead. 2 When a class has the final modifier, all the methods are automatically final. 3 Sometimes two 'if' statements can be consolidated by separating their conditions with a boolean short-circuit operator. 3 The overriding method merely calls the same method defined in a superclass 3 if you need to get an array of a class from your Collection, you should pass an array of the desidered class as the parameter of the toArray method. Otherwise you will get a ClassCastException. 3 One might assume that "new BigDecimal(.1)" is exactly equal to .1, but it is actually equal to .1000000000000000055511151231257827021181583404541015625. This is so because .1 cannot be represented exactly as a double (or, for that matter, as a binary fraction of any finite length). Thus, the long value that is being passed in to the constructor is not exactly equal to .1, appearances notwithstanding. The (String) constructor, on the other hand, is perfectly predictable: 'new BigDecimal(".1")' is exactly equal to .1, as one would expect. Therefore, it is generally recommended that the (String) constructor be used in preference to this one. 3 An operation on an Immutable object (String, BigDecimal or BigInteger) won't change the object itself. The result of the operation is a new object. Therefore, ignoring the operation result is an error. 3 The null check here is misplaced. if the variable is null you'll get a NullPointerException. Either the check is useless (the variable will never be "null") or it's incorrect. 3 After checking an object reference for null, you should invoke equals() on that object rather than passing it to another object's equals() method. 3 Avoid using ThreadGroup; although it is intended to be used in a threaded environment it contains methods that are not thread safe. 3 The null check is broken since it will throw a NullPointerException itself. It is likely that you used || instead of && or vice versa. 2 Don't create instances of already existing BigInteger (BigInteger.ZERO, BigInteger.ONE) and for 1.5 on, BigInteger.TEN and BigDecimal (BigDecimal.ZERO, BigDecimal.ONE, BigDecimal.TEN) 3 3 3 3 2 An empty initializer was found. 3