org.sonar.java.checks.ObjectEqualsNullCheck Maven / Gradle / Ivy
/*
* SonarQube Java
* Copyright (C) 2012-2016 SonarSource SA
* mailto:contact AT sonarsource DOT com
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 3 of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
package org.sonar.java.checks;
import org.sonar.api.server.rule.RulesDefinition;
import org.sonar.check.Priority;
import org.sonar.check.Rule;
import org.sonar.plugins.java.api.JavaFileScanner;
import org.sonar.plugins.java.api.JavaFileScannerContext;
import org.sonar.plugins.java.api.tree.BaseTreeVisitor;
import org.sonar.plugins.java.api.tree.ExpressionTree;
import org.sonar.plugins.java.api.tree.MemberSelectExpressionTree;
import org.sonar.plugins.java.api.tree.MethodInvocationTree;
import org.sonar.plugins.java.api.tree.Tree;
import org.sonar.squidbridge.annotations.SqaleConstantRemediation;
import org.sonar.squidbridge.annotations.SqaleSubCharacteristic;
@Rule(
key = "S1318",
name = "\"object == null\" should be used instead of \"object.equals(null)\"",
priority = Priority.CRITICAL,
status = "DEPRECATED",
tags = {})
@SqaleSubCharacteristic(RulesDefinition.SubCharacteristics.INSTRUCTION_RELIABILITY)
@SqaleConstantRemediation("5min")
public class ObjectEqualsNullCheck extends BaseTreeVisitor implements JavaFileScanner {
private JavaFileScannerContext context;
@Override
public void scanFile(final JavaFileScannerContext context) {
this.context = context;
scan(context.getTree());
}
@Override
public void visitMethodInvocation(MethodInvocationTree tree) {
super.visitMethodInvocation(tree);
if (isCallToEquals(tree.methodSelect()) &&
tree.arguments().size() == 1 &&
isNull(tree.arguments().get(0))) {
context.reportIssue(this, tree, "Use \"object == null\" instead of \"object.equals(null)\" to test for nullity to prevent null pointer exceptions.");
}
}
private static boolean isCallToEquals(ExpressionTree tree) {
if (!tree.is(Tree.Kind.MEMBER_SELECT)) {
return false;
}
MemberSelectExpressionTree memberSelect = (MemberSelectExpressionTree) tree;
return "equals".equals(memberSelect.identifier().name());
}
private static boolean isNull(ExpressionTree tree) {
return tree.is(Tree.Kind.NULL_LITERAL);
}
}
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