Java tutorial
/* * Copyright 2018 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. */ package com.google.errorprone.bugpatterns.time; import static com.google.errorprone.BugPattern.ProvidesFix.REQUIRES_HUMAN_ATTENTION; import static com.google.errorprone.BugPattern.SeverityLevel.WARNING; import com.google.common.collect.Iterables; import com.google.errorprone.BugPattern; import com.google.errorprone.VisitorState; import com.google.errorprone.bugpatterns.BugChecker; import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher; 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.Matchers; import com.google.errorprone.util.ASTHelpers; import com.sun.source.tree.ExpressionTree; import com.sun.source.tree.MethodInvocationTree; /** Check for calls to {@code duration.withSeconds(long)}. */ @BugPattern(name = "JavaDurationWithSeconds", summary = "Use of java.time.Duration.withSeconds(long) is not allowed.", explanation = "Duration's withSeconds(long) method is often a source of bugs because it returns a copy " + "of the current Duration instance, but _only_ the seconds field is mutated (the " + "nanos field is copied directly). Use Duration.ofSeconds(seconds, " + "duration.getNano()) instead.", severity = WARNING, providesFix = REQUIRES_HUMAN_ATTENTION) public final class JavaDurationWithSeconds extends BugChecker implements MethodInvocationTreeMatcher { private static final Matcher<ExpressionTree> MATCHER = Matchers.allOf( Matchers.instanceMethod().onExactClass("java.time.Duration").named("withSeconds") .withParameters("long"), // Allow usage by java.time itself Matchers.not(Matchers.packageStartsWith("java.time"))); @Override public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) { if (!MATCHER.matches(tree, state)) { return Description.NO_MATCH; } SuggestedFix.Builder builder = SuggestedFix.builder(); ExpressionTree secondsArg = Iterables.getOnlyElement(tree.getArguments()); ExpressionTree receiver = ASTHelpers.getReceiver(tree); String replacement = SuggestedFixes.qualifyType(state, builder, "java.time.Duration") + ".ofSeconds(" + state.getSourceForNode(secondsArg) + ", " + state.getSourceForNode(receiver) + ".getNano())"; builder.replace(tree, replacement); return describeMatch(tree, builder.build()); } }