/*
* Copyright 2012 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.instanceMethod;
import static com.google.errorprone.matchers.Matchers.methodSelect;
import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
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.google.errorprone.util.ASTHelpers;
import com.sun.source.tree.ExpressionTree;
import com.sun.source.tree.MethodInvocationTree;
/**
* @author adgar@google.com (Mike Edgar)
*/
@BugPattern(name = "ArrayToString",
summary = "Calling toString on an array does not provide useful information",
explanation =
"The toString method on an array will print its identity, such as [I@4488aabb. This " +
"is almost never needed. Use Arrays.toString to print a human-readable array summary.",
category = JDK, severity = ERROR, maturity = MATURE)
public class ArrayToString extends BugChecker implements MethodInvocationTreeMatcher {
/**
* Matches calls to Throwable.getStackTrace().
*/
private static final Matcher<MethodInvocationTree> getStackTraceMatcher = methodSelect(
instanceMethod(Matchers.<ExpressionTree>isSubtypeOf("java.lang.Throwable"), "getStackTrace"));
/**
* Matches calls to a toString instance method in which the receiver is an array type.
*/
@Override
public Description matchMethodInvocation(MethodInvocationTree methodTree, VisitorState state) {
if (!methodSelect(instanceMethod(Matchers.<ExpressionTree>isArrayType(), "toString"))
.matches(methodTree, state)) {
return Description.NO_MATCH;
}
/*
* Fixes instances of calling toString() on an array. If the array is the result of calling
* e.getStackTrace(), replaces e.getStackTrace().toString() with Guava's
* Throwables.getStackTraceAsString(e).
* Otherwise, replaces a.toString() with Arrays.toString(a).
*/
Fix fix;
ExpressionTree receiverTree = ASTHelpers.getReceiver(methodTree);
if (receiverTree instanceof MethodInvocationTree &&
getStackTraceMatcher.matches((MethodInvocationTree) receiverTree, state)) {
String throwable = ASTHelpers.getReceiver(receiverTree).toString();
fix = SuggestedFix.builder()
.replace(methodTree, "Throwables.getStackTraceAsString(" + throwable + ")")
.addImport("com.google.common.base.Throwables")
.build();
} else {
fix = SuggestedFix.builder()
.replace(methodTree, "Arrays.toString(" + receiverTree + ")")
.addImport("java.util.Arrays")
.build();
}
return describeMatch(methodTree, fix);
}
}