/*
* Copyright 2013 Google Inc. All Rights Reserved.
*
* 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.
*/
package com.google.errorprone.bugpatterns;
import static com.google.errorprone.BugPattern.Category.JDK;
import static com.google.errorprone.BugPattern.MaturityLevel.MATURE;
import static com.google.errorprone.BugPattern.SeverityLevel.ERROR;
import static com.google.errorprone.matchers.Matchers.compoundAssignment;
import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.CompoundAssignmentTreeMatcher;
import com.google.errorprone.fixes.Fix;
import com.google.errorprone.fixes.SuggestedFix;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.matchers.Matcher;
import com.google.errorprone.matchers.Matchers;
import com.sun.source.tree.CompoundAssignmentTree;
import com.sun.source.tree.ExpressionTree;
import com.sun.source.tree.Tree.Kind;
/**
* @author adgar@google.com (Mike Edgar)
*/
@BugPattern(name = "ArrayToStringCompoundAssignment",
summary = "Implicit toString used on an array (String += Array)",
explanation =
"When concatenating-and-assigning an array to a string, the implicit toString call on " +
"the array will yield its identity, such as [I@4488aabb. This is almost never needed. " +
"Use Arrays.toString to obtain a human-readable array summary.",
category = JDK, severity = ERROR, maturity = MATURE)
public class ArrayToStringCompoundAssignment
extends BugChecker implements CompoundAssignmentTreeMatcher {
private static final Matcher<CompoundAssignmentTree> assignmentMatcher =
compoundAssignment(
Kind.PLUS_ASSIGNMENT,
Matchers.<ExpressionTree>isSameType("java.lang.String"),
Matchers.<ExpressionTree>isArrayType());
/**
* Matchers when a string concatenates-and-assigns an array.
*/
@Override
public Description matchCompoundAssignment(CompoundAssignmentTree t, VisitorState state) {
if (!assignmentMatcher.matches(t, state)) {
return Description.NO_MATCH;
}
/*
* Replace instances of implicit array toString() calls due to string
* concatenation-and-assignment with Arrays.toString(array). Also adds
* the necessary import statement for java.util.Arrays.
*/
String receiver = t.getVariable().toString();
String expression = t.getExpression().toString();
Fix fix = SuggestedFix.builder()
.replace(t, receiver + " += Arrays.toString(" + expression + ")")
.addImport("java.util.Arrays")
.build();
return describeMatch(t, fix);
}
}