Simplify boolean expression sonar
If you have a class that has nothing but static methods, consider making it a Singleton. Note that this doesn't apply to abstract classes, since their subclasses may well include non-static methods. Also, if you want this class to be a Singleton, remember to add simplify boolean expression sonar private constructor to prevent instantiation.
This rule is defined by the following Java class: Reassigning values to parameters is a questionable practice. Use a temporary local variable instead.
A high ratio of statements to labels in a switch statement implies that the switch statement is doing too much work. Consider moving the statements into new methods, or creating subclasses based on the switch variable. Calling overridable methods during construction poses a risk of invoking methods on an incompletely constructed object and can be difficult to discern.
It may leave the sub-class unable to construct its superclass or forced to replicate the construction process completely within itself, losing the ability to call super.
If the default constructor contains a call to an overridable method, the subclass may be completely uninstantiable. Note that this includes method calls throughout the control flow graph - i. Instantiation by way of private constructors from outside of the constructor's class often causes the generation of an accessor. A factory method, or non-privitization of the constructor can eliminate this situation.
The generated class file is actually an interface. It gives the accessing class the ability to invoke a new hidden package scope constructor that takes the interface as a supplementary parameter. This turns a private constructor simplify boolean expression sonar into one with package scope, and is challenging to discern. If a final field is assigned to a compile-time constant, it could be made static, thus saving overhead in each object at runtime. Ensure that resources like Connection, Statement, and ResultSet objects are always closed after use.
A nonstatic initializer block will be called any time a constructor is invoked just prior to invoking the constructor. While this is a valid language construct, it is rarely used and is confusing. A non-case simplify boolean expression sonar e. This legal, but confusing. It is easy to mix up the case labels and simplify boolean expression sonar non-case labels.
A call to Collection. Inexperienced programmers sometimes confuse comparison concepts and use equals to compare to null. In an "if" expression with an "else" clause, avoid negation in the test. Also, this resolves trivial ordering problems, such as "does the simplify boolean expression sonar case go first?
Avoid instantiating an object just to call getClass on it; use the. Identifies private fields whose values simplify boolean expression sonar change once they are initialized either in the declaration of the field or by a constructor. This aids in converting existing simplify boolean expression sonar to immutable classes.
When doing a String. This avoids problems with certain locales, i. Do not use protected fields in final classes since they cannot be subclassed. Clarify your intent by using private or package access modifiers instead. A class that has private constructors and does not have any static methods or fields cannot be used. Method level synchronization can backfire when new code is added simplify boolean expression sonar the method. Block-level synchronization helps to ensure that only the code that needs synchronization gets it.
If more than one thread is monitoring, then only one is chosen. The thread chosen is arbitrary; thus it's usually safer to call notifyAll instead. The abstract class does not contain any abstract methods. An abstract class suggests an incomplete implementation, which is to be completed by subclasses implementing the abstract methods. If the class is intended to be used as a base class only not to be instantiated direcly a protected constructor can be provided prevent direct instantiation.
No need to check for simplify boolean expression sonar before an instanceof; the instanceof keyword returns false when given a null argument. Position literals first in String comparisons - that way if the String is null you won't get a NullPointerException, it'll just return false. Non-thread safe singletons can result in bad state changes. Eliminate static singletons if possible by instantiating the object directly. Static singletons are usually not needed as only a single instance exists anyway.
Other possible fixes are to synchronize the entire method or to use an initialize-on-demand holder class do not use the double-check idiom. See Effective Java, item Uncommented Empty Method finds instances where a method does not contain statements, but there is no comment.
By explicitly commenting empty methods it is easier to distinguish between intentional commented and unintentional empty methods. Uncommented Empty Constructor finds instances where a constructor does not contain statements, but there is no comment.
By explicitly commenting empty constructors it is easier to distinguish between intentional commented and unintentional empty constructors. An interface should be used only to model a behaviour of a class: SimpleDateFormat is not synchronized. Sun recomends separate format instances for each thread. If multiple threads must access a static formatter, the formatter must be synchronized either on method or simplify boolean expression sonar level.
Throwing a new exception from a catch simplify boolean expression sonar without passing the original exception into the new exception will cause the true stack trace to be lost, and can make it difficult to debug effectively. The isEmpty method on java. Collection is provided to see if a collection has any elements. Comparing the value of size to 0 merely duplicates existing behavior.
A class with only private constructors should be final, unless the private constructor is called by a inner class. An empty method in an abstract class should be abstract instead, as developer may rely on this empty implementation rather than code the appropriate one. This field is used in only one method and the first usage is assigning a value to the field.
This probably means that the field can be changed to a local variable. For any method that returns an array, it's a better behavior to return an empty array rather than a null simplify boolean expression sonar. If the abstract class does not provides any methods, it may be just a data container that is not to be instantiated.
In this case, it's probably better to use a private or a protected constructor in order to prevent instantiation than make the class misleadingly abstract. Swith are designed complex branches, and allow branches to share treatement. Using a switch for only a few branches is ill advised, as switches are not as easy to understand as if. In this case, it's most likely is a good simplify boolean expression sonar to use a if statement instead, at least to increase code readability.
Overview Download PMD 4. Legend External Link Opens in a new window. Design Rules The Design Ruleset contains a collection of rules that find questionable designs.
This rule is defined by the following XPath expression: NaN - these are likely to be logic errors.
This code says the author missed some key points about booleans. You can find it in almost any language. Any code that fits into an if or while eventually becomes a boolean.
That code can be simplified down to this one-liner:. You can probably stop reading here, but thanks for stopping by. There are many other ways to tame a wild boolean — follow that link, and check the simplify boolean expression sonar table. These handy unit tests tell us how it simplify boolean expression sonar. We can just say if tooMuch. When a b is evaluated, if a is true, the expression evaluates to true, without even checking b ; but if a is false, then the expression evaluates to the value of b.
That block just becomes:. Sounds like an AND expression. We can in-line those variables, and it gets even clearer:. Most of them are easy to remember, and can be easily illustrated in real-life terms.
These rules are part of a larger topic called Boolean algebrawhich is useful for simplifying circuitsand of course programming. I found some C today that looked kind of like this. That code can be simplified down to this one-liner: What simplify boolean expression sonar your boolean values are swapped?
You can invert your condition: These handy unit tests tell us how it behaves: That block just becomes: We can in-line those variables, and it gets even clearer: