Interfaces by definition are abstract so the {@code abstract} * modifier on the interface is redundant. * *
Classes inside of interfaces by definition are public and static, * so the {@code public} and {@code static} modifiers * on the inner classes are redundant. On the other hand, classes * inside of interfaces can be abstract or non abstract. * So, {@code abstract} modifier is allowed. * *
Fields in interfaces and annotations are automatically * public, static and final, so these modifiers are redundant as * well.
* *As annotations are a form of interface, their fields are also * automatically public, static and final just as their * annotation fields are automatically public and abstract.
* *Enums by definition are static implicit subclasses of java.lang.Enum<E>. * So, the {@code static} modifier on the enums is redundant. In addition, * if enum is inside of interface, {@code public} modifier is also redundant.
* *Enums can also contain abstract methods and methods which can be overridden by the declared * enumeration fields. * See the following example:
*
* public enum EnumClass {
* FIELD_1,
* FIELD_2 {
* @Override
* public final void method1() {} // violation expected
* };
*
* public void method1() {}
* public final void method2() {} // no violation expected
* }
*
*
* Since these methods can be overridden in these situations, the final methods are not * marked as redundant even though they can't be extended by other classes/enums.
* *Final classes by definition cannot be extended so the {@code final} * modifier on the method of a final class is redundant. * *
Public modifier for constructors in non-public non-protected classes * is always obsolete:
* *
* public class PublicClass {
* public PublicClass() {} // OK
* }
*
* class PackagePrivateClass {
* public PackagePrivateClass() {} // violation expected
* }
*
*
* There is no violation in the following example, * because removing public modifier from ProtectedInnerClass * constructor will make this code not compiling:
* *
* package a;
* public class ClassExample {
* protected class ProtectedInnerClass {
* public ProtectedInnerClass () {}
* }
* }
*
* package b;
* import a.ClassExample;
* public class ClassExtending extends ClassExample {
* ProtectedInnerClass pc = new ProtectedInnerClass();
* }
*
*
* @author lkuehne
* @author liscju
* @author Andrei Selkin
* @author Vladislav Lisetskiy
*/
@StatelessCheck
public class RedundantModifierCheck
extends AbstractCheck {
/**
* A key is pointing to the warning message text in "messages.properties"
* file.
*/
public static final String MSG_KEY = "redundantModifier";
/**
* An array of tokens for interface modifiers.
*/
private static final int[] TOKENS_FOR_INTERFACE_MODIFIERS = {
TokenTypes.LITERAL_STATIC,
TokenTypes.ABSTRACT,
};
@Override
public int[] getDefaultTokens() {
return getAcceptableTokens();
}
@Override
public int[] getRequiredTokens() {
return CommonUtils.EMPTY_INT_ARRAY;
}
@Override
public int[] getAcceptableTokens() {
return new int[] {
TokenTypes.METHOD_DEF,
TokenTypes.VARIABLE_DEF,
TokenTypes.ANNOTATION_FIELD_DEF,
TokenTypes.INTERFACE_DEF,
TokenTypes.CTOR_DEF,
TokenTypes.CLASS_DEF,
TokenTypes.ENUM_DEF,
TokenTypes.RESOURCE,
};
}
@Override
public void visitToken(DetailAST ast) {
if (ast.getType() == TokenTypes.INTERFACE_DEF) {
checkInterfaceModifiers(ast);
}
else if (ast.getType() == TokenTypes.ENUM_DEF) {
checkEnumDef(ast);
}
else {
if (ast.getType() == TokenTypes.CTOR_DEF) {
if (isEnumMember(ast)) {
checkEnumConstructorModifiers(ast);
}
else {
checkClassConstructorModifiers(ast);
}
}
else if (ast.getType() == TokenTypes.METHOD_DEF) {
processMethods(ast);
}
else if (ast.getType() == TokenTypes.RESOURCE) {
processResources(ast);
}
if (isInterfaceOrAnnotationMember(ast)) {
processInterfaceOrAnnotation(ast);
}
}
}
/**
* Checks if interface has proper modifiers.
* @param ast interface to check
*/
private void checkInterfaceModifiers(DetailAST ast) {
final DetailAST modifiers =
ast.findFirstToken(TokenTypes.MODIFIERS);
for (final int tokenType : TOKENS_FOR_INTERFACE_MODIFIERS) {
final DetailAST modifier =
modifiers.findFirstToken(tokenType);
if (modifier != null) {
log(modifier.getLineNo(), modifier.getColumnNo(),
MSG_KEY, modifier.getText());
}
}
}
/**
* Check if enum constructor has proper modifiers.
* @param ast constructor of enum
*/
private void checkEnumConstructorModifiers(DetailAST ast) {
final DetailAST modifiers = ast.findFirstToken(TokenTypes.MODIFIERS);
final DetailAST modifier = getFirstModifierAst(modifiers);
if (modifier != null) {
log(modifier.getLineNo(), modifier.getColumnNo(),
MSG_KEY, modifier.getText());
}
}
/**
* Retrieves the first modifier that is not an annotation.
* @param modifiers The ast to examine.
* @return The first modifier or {@code null} if none found.
*/
private static DetailAST getFirstModifierAst(DetailAST modifiers) {
DetailAST modifier = modifiers.getFirstChild();
while (modifier != null && modifier.getType() == TokenTypes.ANNOTATION) {
modifier = modifier.getNextSibling();
}
return modifier;
}
/**
* Checks whether enum has proper modifiers.
* @param ast enum definition.
*/
private void checkEnumDef(DetailAST ast) {
if (isInterfaceOrAnnotationMember(ast)) {
processInterfaceOrAnnotation(ast);
}
else if (ast.getParent() != null) {
checkForRedundantModifier(ast, TokenTypes.LITERAL_STATIC);
}
}
/**
* Do validation of interface of annotation.
* @param ast token AST
*/
private void processInterfaceOrAnnotation(DetailAST ast) {
final DetailAST modifiers = ast.findFirstToken(TokenTypes.MODIFIERS);
DetailAST modifier = modifiers.getFirstChild();
while (modifier != null) {
// javac does not allow final or static in interface methods
// order annotation fields hence no need to check that this
// is not a method or annotation field
final int type = modifier.getType();
if (type == TokenTypes.LITERAL_PUBLIC
|| type == TokenTypes.LITERAL_STATIC
&& ast.getType() != TokenTypes.METHOD_DEF
|| type == TokenTypes.ABSTRACT
&& ast.getType() != TokenTypes.CLASS_DEF
|| type == TokenTypes.FINAL
&& ast.getType() != TokenTypes.CLASS_DEF) {
log(modifier.getLineNo(), modifier.getColumnNo(),
MSG_KEY, modifier.getText());
break;
}
modifier = modifier.getNextSibling();
}
}
/**
* Process validation of Methods.
* @param ast method AST
*/
private void processMethods(DetailAST ast) {
final DetailAST modifiers =
ast.findFirstToken(TokenTypes.MODIFIERS);
// private method?
boolean checkFinal =
modifiers.findFirstToken(TokenTypes.LITERAL_PRIVATE) != null;
// declared in a final class?
DetailAST parent = ast.getParent();
while (parent != null && !checkFinal) {
if (parent.getType() == TokenTypes.CLASS_DEF) {
final DetailAST classModifiers =
parent.findFirstToken(TokenTypes.MODIFIERS);
checkFinal = classModifiers.findFirstToken(TokenTypes.FINAL) != null;
parent = null;
}
else if (parent.getType() == TokenTypes.LITERAL_NEW
|| parent.getType() == TokenTypes.ENUM_CONSTANT_DEF) {
checkFinal = true;
parent = null;
}
else if (parent.getType() == TokenTypes.ENUM_DEF) {
checkFinal = modifiers.findFirstToken(TokenTypes.LITERAL_STATIC) != null;
parent = null;
}
else {
parent = parent.getParent();
}
}
if (checkFinal && !isAnnotatedWithSafeVarargs(ast)) {
checkForRedundantModifier(ast, TokenTypes.FINAL);
}
if (ast.findFirstToken(TokenTypes.SLIST) == null) {
processAbstractMethodParameters(ast);
}
}
/**
* Process validation of parameters for Methods with no definition.
* @param ast method AST
*/
private void processAbstractMethodParameters(DetailAST ast) {
final DetailAST parameters = ast.findFirstToken(TokenTypes.PARAMETERS);
for (DetailAST child = parameters.getFirstChild(); child != null; child = child
.getNextSibling()) {
if (child.getType() == TokenTypes.PARAMETER_DEF) {
checkForRedundantModifier(child, TokenTypes.FINAL);
}
}
}
/**
* Check if class constructor has proper modifiers.
* @param classCtorAst class constructor ast
*/
private void checkClassConstructorModifiers(DetailAST classCtorAst) {
final DetailAST classDef = classCtorAst.getParent().getParent();
if (!isClassPublic(classDef) && !isClassProtected(classDef)) {
checkForRedundantModifier(classCtorAst, TokenTypes.LITERAL_PUBLIC);
}
}
/**
* Checks if given resource has redundant modifiers.
* @param ast ast
*/
private void processResources(DetailAST ast) {
checkForRedundantModifier(ast, TokenTypes.FINAL);
}
/**
* Checks if given ast has a redundant modifier.
* @param ast ast
* @param modifierType The modifier to check for.
*/
private void checkForRedundantModifier(DetailAST ast, int modifierType) {
final DetailAST astModifiers = ast.findFirstToken(TokenTypes.MODIFIERS);
DetailAST astModifier = astModifiers.getFirstChild();
while (astModifier != null) {
if (astModifier.getType() == modifierType) {
log(astModifier.getLineNo(), astModifier.getColumnNo(),
MSG_KEY, astModifier.getText());
}
astModifier = astModifier.getNextSibling();
}
}
/**
* Checks if given class ast has protected modifier.
* @param classDef class ast
* @return true if class is protected, false otherwise
*/
private static boolean isClassProtected(DetailAST classDef) {
final DetailAST classModifiers =
classDef.findFirstToken(TokenTypes.MODIFIERS);
return classModifiers.findFirstToken(TokenTypes.LITERAL_PROTECTED) != null;
}
/**
* Checks if given class is accessible from "public" scope.
* @param ast class def to check
* @return true if class is accessible from public scope,false otherwise
*/
private static boolean isClassPublic(DetailAST ast) {
boolean isAccessibleFromPublic = false;
final boolean isMostOuterScope = ast.getParent() == null;
final DetailAST modifiersAst = ast.findFirstToken(TokenTypes.MODIFIERS);
final boolean hasPublicModifier =
modifiersAst.findFirstToken(TokenTypes.LITERAL_PUBLIC) != null;
if (isMostOuterScope) {
isAccessibleFromPublic = hasPublicModifier;
}
else {
final DetailAST parentClassAst = ast.getParent().getParent();
if (hasPublicModifier || parentClassAst.getType() == TokenTypes.INTERFACE_DEF) {
isAccessibleFromPublic = isClassPublic(parentClassAst);
}
}
return isAccessibleFromPublic;
}
/**
* Checks if current AST node is member of Enum.
* @param ast AST node
* @return true if it is an enum member
*/
private static boolean isEnumMember(DetailAST ast) {
final DetailAST parentTypeDef = ast.getParent().getParent();
return parentTypeDef.getType() == TokenTypes.ENUM_DEF;
}
/**
* Checks if current AST node is member of Interface or Annotation, not of their subnodes.
* @param ast AST node
* @return true or false
*/
private static boolean isInterfaceOrAnnotationMember(DetailAST ast) {
DetailAST parentTypeDef = ast.getParent();
if (parentTypeDef != null) {
parentTypeDef = parentTypeDef.getParent();
}
return parentTypeDef != null
&& (parentTypeDef.getType() == TokenTypes.INTERFACE_DEF
|| parentTypeDef.getType() == TokenTypes.ANNOTATION_DEF);
}
/**
* Checks if method definition is annotated with.
*
* SafeVarargs annotation
* @param methodDef method definition node
* @return true or false
*/
private static boolean isAnnotatedWithSafeVarargs(DetailAST methodDef) {
boolean result = false;
final List