com.google.errorprone.bugpatterns.PublicConstructorForAbstractClass Maven / Gradle / Ivy
/*
* Copyright 2020 The Error Prone Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
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package com.google.errorprone.bugpatterns;
import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
import static com.google.errorprone.matchers.Description.NO_MATCH;
import static com.google.errorprone.matchers.Matchers.allOf;
import static com.google.errorprone.matchers.Matchers.enclosingClass;
import static com.google.errorprone.matchers.Matchers.hasModifier;
import static com.google.errorprone.matchers.Matchers.methodHasVisibility;
import static com.google.errorprone.matchers.Matchers.methodIsConstructor;
import static javax.lang.model.element.Modifier.ABSTRACT;
import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.MethodTreeMatcher;
import com.google.errorprone.fixes.SuggestedFix;
import com.google.errorprone.fixes.SuggestedFixes;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.matchers.Matcher;
import com.google.errorprone.matchers.MethodVisibility;
import com.sun.source.tree.MethodTree;
import javax.lang.model.element.Modifier;
/** A {@link BugChecker}; see the associated {@link BugPattern} annotation for details. */
@BugPattern(
name = "PublicConstructorForAbstractClass",
summary =
"Constructors of an abstract class can be declared protected as there is never a need"
+ " for them to be public",
explanation =
"Abstract classes' constructors are only ever called by subclasses, never directly by"
+ " another class. Therefore they never need public constructors: protected is"
+ " accessible enough.",
severity = SUGGESTION)
public class PublicConstructorForAbstractClass extends BugChecker implements MethodTreeMatcher {
private static final Matcher PUBLIC_ABSTRACT_CONSTRUCTOR =
allOf(
methodIsConstructor(),
methodHasVisibility(MethodVisibility.Visibility.PUBLIC),
enclosingClass(hasModifier(ABSTRACT)));
@Override
public Description matchMethod(MethodTree tree, VisitorState state) {
if (!PUBLIC_ABSTRACT_CONSTRUCTOR.matches(tree, state)) {
return NO_MATCH;
}
SuggestedFix.Builder fix = SuggestedFix.builder();
SuggestedFixes.removeModifiers(tree, state, Modifier.PUBLIC).ifPresent(fix::merge);
SuggestedFixes.addModifiers(tree, state, Modifier.PROTECTED).ifPresent(fix::merge);
return describeMatch(tree, fix.build());
}
}