TriStateDecorator
has 25 methods (exceeds 20 allowed). Consider refactoring. Open
private final class TriStateDecorator implements ButtonModel {
private final ButtonModel other;
private TriStateDecorator(final ButtonModel other) {
this.other = other;
Add a nested comment explaining why this method is empty, throw an UnsupportedOperationException or complete the implementation. Open
public void addMouseListener(final MouseListener l) {
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There are several reasons for a method not to have a method body:
- It is an unintentional omission, and should be fixed to prevent an unexpected behavior in production.
- It is not yet, or never will be, supported. In this case an
UnsupportedOperationException
should be thrown. - The method is an intentionally-blank override. In this case a nested comment should explain the reason for the blank override.
Noncompliant Code Example
public void doSomething() { } public void doSomethingElse() { }
Compliant Solution
@Override public void doSomething() { // Do nothing because of X and Y. } @Override public void doSomethingElse() { throw new UnsupportedOperationException(); }
Exceptions
Default (no-argument) constructors are ignored when there are other constructors in the class, as are empty methods in abstract classes.
public abstract class Animal { void speak() { // default implementation ignored } }
Make this method "synchronized" to match the parent class implementation. Open
public void addMouseListener(final MouseListener l) {
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When @Overrides
of synchronized
methods are not themselves synchronized
, the result can be improper
synchronization as callers rely on the thread-safety promised by the parent class.
Noncompliant Code Example
public class Parent { synchronized void foo() { //... } } public class Child extends Parent { @Override public void foo () { // Noncompliant // ... super.foo(); } }
Compliant Solution
public class Parent { synchronized void foo() { //... } } public class Child extends Parent { @Override synchronized void foo () { // ... super.foo(); } }
See
- CERT, TSM00-J - Do not override thread-safe methods with methods that are not thread-safe
Make "decorator" transient or serializable. Open
private final TriStateDecorator decorator;
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Fields in a Serializable
class must themselves be either Serializable
or transient
even if the class is
never explicitly serialized or deserialized. For instance, under load, most J2EE application frameworks flush objects to disk, and an allegedly
Serializable
object with non-transient, non-serializable data members could cause program crashes, and open the door to attackers. In
general a Serializable
class is expected to fulfil its contract and not have an unexpected behaviour when an instance is serialized.
This rule raises an issue on non-Serializable
fields, and on collection fields when they are not private
(because they
could be assigned non-Serializable
values externally), and when they are assigned non-Serializable
types within the
class.
Noncompliant Code Example
public class Address { //... } public class Person implements Serializable { private static final long serialVersionUID = 1905122041950251207L; private String name; private Address address; // Noncompliant; Address isn't serializable }
Compliant Solution
public class Address implements Serializable { private static final long serialVersionUID = 2405172041950251807L; } public class Person implements Serializable { private static final long serialVersionUID = 1905122041950251207L; private String name; private Address address; }
Exceptions
The alternative to making all members serializable
or transient
is to implement special methods which take on the
responsibility of properly serializing and de-serializing the object. This rule ignores classes which implement the following methods:
private void writeObject(java.io.ObjectOutputStream out) throws IOException private void readObject(java.io.ObjectInputStream in) throws IOException, ClassNotFoundException;
See
- MITRE, CWE-594 - Saving Unserializable Objects to Disk
- Oracle Java 6, Serializable
- Oracle Java 7, Serializable
Parameter name 'e' must match pattern '^[a-z][a-z0-9][a-zA-Z0-9]*$'. Open
public void mousePressed(final MouseEvent e) {
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Checks that method parameter names conform to a specified pattern.By using accessModifiers
property it is possibleto specify different formats for methods at different visibility levels.
To validate catch
parameters please useCatchParameterName.
To validate lambda parameters please useLambdaParameterName.
This documentation is written and maintained by the Checkstyle community and is covered under the same license as the Checkstyle project.
Extra separation in import group before 'javax.swing.*' Open
import javax.swing.*;
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Checks that the groups of import declarations appear in the order specifiedby the user. If there is an import but its group is not specified in theconfiguration such an import should be placed at the end of the import list.
This documentation is written and maintained by the Checkstyle community and is covered under the same license as the Checkstyle project.
Parameter name 'l' must match pattern '^[a-z][a-z0-9][a-zA-Z0-9]*$'. Open
public void addMouseListener(final MouseListener l) {
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Checks that method parameter names conform to a specified pattern.By using accessModifiers
property it is possibleto specify different formats for methods at different visibility levels.
To validate catch
parameters please useCatchParameterName.
To validate lambda parameters please useLambdaParameterName.
This documentation is written and maintained by the Checkstyle community and is covered under the same license as the Checkstyle project.
Using the '.*' form of import should be avoided - javax.swing.*. Open
import javax.swing.*;
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Checks that there are no import statements that use the *
notation.
Rationale: Importing all classes from a package or staticmembers from a class leads to tight coupling between packagesor classes and might lead to problems when a new version of alibrary introduces name clashes.
This documentation is written and maintained by the Checkstyle community and is covered under the same license as the Checkstyle project.
Parameter name 'e' must match pattern '^[a-z][a-z0-9][a-zA-Z0-9]*$'. Open
public void actionPerformed(final ActionEvent e) {
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Checks that method parameter names conform to a specified pattern.By using accessModifiers
property it is possibleto specify different formats for methods at different visibility levels.
To validate catch
parameters please useCatchParameterName.
To validate lambda parameters please useLambdaParameterName.
This documentation is written and maintained by the Checkstyle community and is covered under the same license as the Checkstyle project.
First sentence of Javadoc is missing an ending period. Open
/**
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Checks thatJavadoc summary sentence does not contain phrases that are not recommended to use.Summaries that contain only the {@inheritDoc}
tag are skipped. Check alsoviolate Javadoc that does not contain first sentence.
This documentation is written and maintained by the Checkstyle community and is covered under the same license as the Checkstyle project.