Minor Description
Google has a tool at http://errorprone.info. From that page
Using Error Prone to augment the compiler’s type analysis, you can catch more mistakes before they cost you time, or end up as bugs in production.
It requires java 1.8. In the top level pom, replacing
<plugin> <artifactId>maven-compiler-plugin</artifactId> <configuration> <source>${java.ver}</source> <target>${java.ver}</target> <optimize>true</optimize> <showDeprecation>true</showDeprecation> <showWarnings>true</showWarnings> </configuration> </plugin>
with
<plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.3</version> <configuration> <compilerId>javac-with-errorprone</compilerId> <forceJavacCompilerUse>true</forceJavacCompilerUse> <!-- maven-compiler-plugin defaults to targeting Java 5, but our javac only supports >=6 --> <source>${java.ver}</source> <target>${java.ver}</target> <compilerArgs> <arg>-Xep:ChainingConstructorIgnoresParameter:WARN</arg> <arg>-Xep:LongLiteralLowerCaseSuffix:OFF</arg> <arg>-Xep:SizeGreaterThanOrEqualsZero:WARN</arg> <arg>-Xep:InvalidPatternSyntax:WARN</arg> <arg>-Xep:TryFailThrowable:WARN</arg> <arg>-Xep:NonOverridingEquals:OFF</arg> </compilerArgs> <showWarnings>true</showWarnings> </configuration> <dependencies> <!-- override plexus-compiler-javac-errorprone's dependency on Error Prone with the latest version --> <dependency> <groupId>com.google.errorprone</groupId> <artifactId>error_prone_core</artifactId> <version>2.0.8</version> </dependency> <dependency> <groupId>org.codehaus.plexus</groupId> <artifactId>plexus-compiler-javac-errorprone</artifactId> <version>2.5</version> </dependency> </dependencies> </plugin>
in the 1.6 branch and runing 'mvn compile' yielded the following.
[INFO] Scanning for projects...
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Build Order:
[INFO]
[INFO] Apache Accumulo Project
[INFO] Apache Accumulo Trace
[INFO] Apache Accumulo Fate
[INFO] Apache Accumulo Start
[INFO] Apache Accumulo Core
[INFO] Apache Accumulo Simple Examples
[INFO] Apache Accumulo Server Base
[INFO] Apache Accumulo GC Server
[INFO] Apache Accumulo Master Server
[INFO] Apache Accumulo Monitor Server
[INFO] Apache Accumulo Tracer Server
[INFO] Apache Accumulo Tablet Server
[INFO] Apache Accumulo MiniCluster
[INFO] Apache Accumulo Native Libraries
[INFO] Apache Accumulo Testing
[INFO] Apache Accumulo Proxy
[INFO] Apache Accumulo
[INFO] Apache Accumulo Documentation
[INFO] Apache Accumulo Maven Plugin
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building Apache Accumulo Project 1.6.6-SNAPSHOT
[INFO] ------------------------------------------------------------------------
...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building Apache Accumulo Trace 1.6.6-SNAPSHOT
[INFO] ------------------------------------------------------------------------
...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building Apache Accumulo Fate 1.6.6-SNAPSHOT
[INFO] ------------------------------------------------------------------------
...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building Apache Accumulo Start 1.6.6-SNAPSHOT
[INFO] ------------------------------------------------------------------------
...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building Apache Accumulo Core 1.6.6-SNAPSHOT
[INFO] ------------------------------------------------------------------------
...
[INFO] --- maven-compiler-plugin:3.3:compile (default-compile) @ accumulo-core ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 595 source files to /Users/mjwall/NetBeansProjects/accumulo-mjwall/core/target/classes
/Users/mjwall/NetBeansProjects/accumulo-mjwall/core/src/main/java/org/apache/accumulo/core/data/Value.java:80: warning: [ChainingConstructorIgnoresParameter] The called constructor accepts a parameter with the same name and type as one of its caller's parameters, but its caller doesn't pass that parameter to it. It's likely that it was intended to.
this(toBytes(bytes), false);
^
(see http://errorprone.info/bugpattern/ChainingConstructorIgnoresParameter)
Did you mean 'this(toBytes(bytes), copy);'?
/Users/mjwall/NetBeansProjects/accumulo-mjwall/core/src/main/java/org/apache/accumulo/core/client/mapreduce/AccumuloOutputFormat.java:510: warning: [SizeGreaterThanOrEqualsZero] Comparison of a size >= 0 is always true, did you intend to check for non-emptiness?
if (e.getAuthorizationFailuresMap().size() >= 0) {
^
(see http://errorprone.info/bugpattern/SizeGreaterThanOrEqualsZero)
Did you mean 'if (!e.getAuthorizationFailuresMap().isEmpty()) {'?
/Users/mjwall/NetBeansProjects/accumulo-mjwall/core/src/main/java/org/apache/accumulo/core/client/mapreduce/lib/impl/ConfiguratorBase.java:277: warning: [Finally] If you return or throw from a finally, then values returned or thrown from the try-catch block will be ignored. Consider using try-with-resources instead.
throw new RuntimeException(fileScanner.ioException());
^
(see http://errorprone.info/bugpattern/Finally)
/Users/mjwall/NetBeansProjects/accumulo-mjwall/core/src/main/java/org/apache/accumulo/core/client/impl/TabletServerBatchWriter.java:447: warning: [WaitNotInLoop] Because of spurious wakeups, wait() must always be called in a loop
wait();
^
(see http://errorprone.info/bugpattern/WaitNotInLoop)
/Users/mjwall/NetBeansProjects/accumulo-mjwall/core/src/main/java/org/apache/accumulo/core/volume/VolumeImpl.java:109: warning: [EqualsHashCode] Classes that override equals should also override hashCode.
public boolean equals(Object o) {
^
(see http://errorprone.info/bugpattern/EqualsHashCode)
/Users/mjwall/NetBeansProjects/accumulo-mjwall/core/src/main/java/org/apache/accumulo/core/file/blockfile/cache/LruBlockCache.java:444: warning: [EqualsHashCode] Classes that override equals should also override hashCode.
public boolean equals(Object that) {
^
(see http://errorprone.info/bugpattern/EqualsHashCode)
/Users/mjwall/NetBeansProjects/accumulo-mjwall/core/src/main/java/org/apache/accumulo/core/file/FileOperations.java:17: warning: [MultipleTopLevelClasses] Expected at most one top-level class declaration, instead found: DispatchingFileFactory, FileOperations
package org.apache.accumulo.core.file;
^
(see http://errorprone.info/bugpattern/MultipleTopLevelClasses)
/Users/mjwall/NetBeansProjects/accumulo-mjwall/core/src/main/java/org/apache/accumulo/core/util/shell/commands/ConfigCommand.java:211: warning: [InvalidPatternSyntax] Invalid syntax used for a regular expression: "." is a valid but useless regex
siteVal = sysVal = dfault = curVal = curVal.replaceAll(".", "*");
^
(see http://errorprone.info/bugpattern/InvalidPatternSyntax)
Did you mean 'siteVal = sysVal = dfault = curVal = curVal.replaceAll("\\.", "*");'?
/Users/mjwall/NetBeansProjects/accumulo-mjwall/core/src/main/java/org/apache/accumulo/core/client/mapred/AccumuloOutputFormat.java:509: warning: [SizeGreaterThanOrEqualsZero] Comparison of a size >= 0 is always true, did you intend to check for non-emptiness?
if (e.getAuthorizationFailuresMap().size() >= 0) {
^
(see http://errorprone.info/bugpattern/SizeGreaterThanOrEqualsZero)
Did you mean 'if (!e.getAuthorizationFailuresMap().isEmpty()) {'?
/Users/mjwall/NetBeansProjects/accumulo-mjwall/core/src/main/java/org/apache/accumulo/core/client/impl/OfflineScanner.java:17: warning: [MultipleTopLevelClasses] Expected at most one top-level class declaration, instead found: OfflineIterator, OfflineScanner
package org.apache.accumulo.core.client.impl;
^
(see http://errorprone.info/bugpattern/MultipleTopLevelClasses)
/Users/mjwall/NetBeansProjects/accumulo-mjwall/core/src/main/java/org/apache/accumulo/core/client/impl/ConditionalWriterImpl.java:211: warning: [SynchronizeOnNonFinalField] Synchronizing on non-final fields is not safe: if the field is ever updated, different threads may end up locking on different objects.
synchronized (serverQueues) {
^
(see http://errorprone.info/bugpattern/SynchronizeOnNonFinalField)
/Users/mjwall/NetBeansProjects/accumulo-mjwall/core/src/main/java/org/apache/accumulo/core/client/impl/ConditionalWriterImpl.java:487: warning: [SynchronizeOnNonFinalField] Synchronizing on non-final fields is not safe: if the field is ever updated, different threads may end up locking on different objects.
synchronized (cachedSessionIDs) {
^
(see http://errorprone.info/bugpattern/SynchronizeOnNonFinalField)
/Users/mjwall/NetBeansProjects/accumulo-mjwall/core/src/main/java/org/apache/accumulo/core/client/impl/ConditionalWriterImpl.java:505: warning: [SynchronizeOnNonFinalField] Synchronizing on non-final fields is not safe: if the field is ever updated, different threads may end up locking on different objects.
synchronized (cachedSessionIDs) {
^
(see http://errorprone.info/bugpattern/SynchronizeOnNonFinalField)
/Users/mjwall/NetBeansProjects/accumulo-mjwall/core/src/main/java/org/apache/accumulo/core/client/impl/ConditionalWriterImpl.java:521: warning: [SynchronizeOnNonFinalField] Synchronizing on non-final fields is not safe: if the field is ever updated, different threads may end up locking on different objects.
synchronized (cachedSessionIDs) {
^
(see http://errorprone.info/bugpattern/SynchronizeOnNonFinalField)
/Users/mjwall/NetBeansProjects/accumulo-mjwall/core/src/main/java/org/apache/accumulo/core/client/impl/ConditionalWriterImpl.java:528: warning: [SynchronizeOnNonFinalField] Synchronizing on non-final fields is not safe: if the field is ever updated, different threads may end up locking on different objects.
synchronized (cachedSessionIDs) {
^
(see http://errorprone.info/bugpattern/SynchronizeOnNonFinalField)
/Users/mjwall/NetBeansProjects/accumulo-mjwall/core/src/main/java/org/apache/accumulo/core/client/impl/MultiTableBatchWriterImpl.java:218: warning: [SynchronizeOnNonFinalField] Synchronizing on non-final fields is not safe: if the field is ever updated, different threads may end up locking on different objects.
synchronized (tableWriters) {
^
(see http://errorprone.info/bugpattern/SynchronizeOnNonFinalField)
16 warnings
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building Apache Accumulo Simple Examples 1.6.6-SNAPSHOT
[INFO] ------------------------------------------------------------------------
..
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building Apache Accumulo Server Base 1.6.6-SNAPSHOT
[INFO] ------------------------------------------------------------------------
...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building Apache Accumulo GC Server 1.6.6-SNAPSHOT
[INFO] ------------------------------------------------------------------------
...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building Apache Accumulo Master Server 1.6.6-SNAPSHOT
[INFO] ------------------------------------------------------------------------
...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building Apache Accumulo Monitor Server 1.6.6-SNAPSHOT
[INFO] ------------------------------------------------------------------------
...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building Apache Accumulo Tracer Server 1.6.6-SNAPSHOT
[INFO] ------------------------------------------------------------------------
...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building Apache Accumulo Tablet Server 1.6.6-SNAPSHOT
[INFO] ------------------------------------------------------------------------
...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building Apache Accumulo MiniCluster 1.6.6-SNAPSHOT
[INFO] ------------------------------------------------------------------------
...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building Apache Accumulo Native Libraries 1.6.6-SNAPSHOT
[INFO] ------------------------------------------------------------------------
...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building Apache Accumulo Testing 1.6.6-SNAPSHOT
[INFO] ------------------------------------------------------------------------
...
[INFO]
[INFO] --- maven-compiler-plugin:3.3:compile (default-compile) @ accumulo-test ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 176 source files to /Users/mjwall/NetBeansProjects/accumulo-mjwall/test/target/classes
/Users/mjwall/NetBeansProjects/accumulo-mjwall/test/src/main/java/org/apache/accumulo/test/EstimateInMemMapOverhead.java:17: warning: [MultipleTopLevelClasses] Expected at most one top-level class declaration, instead found: MemoryUsageTest, TextMemoryUsageTest, InMemoryMapMemoryUsageTest, MutationMemoryUsageTest, IntObjectMemoryUsageTest, EstimateInMemMapOverhead
package org.apache.accumulo.test;
^
(see http://errorprone.info/bugpattern/MultipleTopLevelClasses)
/Users/mjwall/NetBeansProjects/accumulo-mjwall/test/src/main/java/org/apache/accumulo/test/IMMLGBenchmark.java:129: warning: [ElementsCountedInLoop] This code, which counts elements using a loop, can be replaced by a simpler library method
for (@SuppressWarnings("unused")
^
(see http://errorprone.info/bugpattern/ElementsCountedInLoop)
Did you mean 'count += Iterables.size(scanner);'?
/Users/mjwall/NetBeansProjects/accumulo-mjwall/test/src/main/java/org/apache/accumulo/test/continuous/Histogram.java:17: warning: [MultipleTopLevelClasses] Expected at most one top-level class declaration, instead found: HistData, Histogram
package org.apache.accumulo.test.continuous;
^
(see http://errorprone.info/bugpattern/MultipleTopLevelClasses)
/Users/mjwall/NetBeansProjects/accumulo-mjwall/test/src/main/java/org/apache/accumulo/test/performance/metadata/MetadataBatchScanTest.java:225: warning: [ElementsCountedInLoop] This code, which counts elements using a loop, can be replaced by a simpler library method
for (@SuppressWarnings("unused")
^
(see http://errorprone.info/bugpattern/ElementsCountedInLoop)
Did you mean 'count += Iterables.size(bs);'?
/Users/mjwall/NetBeansProjects/accumulo-mjwall/test/src/main/java/org/apache/accumulo/test/randomwalk/Module.java:402: warning: [SynchronizeOnNonFinalField] Synchronizing on non-final fields is not safe: if the field is ever updated, different threads may end up locking on different objects.
synchronized (timer) {
^
(see http://errorprone.info/bugpattern/SynchronizeOnNonFinalField)
5 warnings
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building Apache Accumulo Proxy 1.6.6-SNAPSHOT
[INFO] ------------------------------------------------------------------------
...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building Apache Accumulo 1.6.6-SNAPSHOT
[INFO] ------------------------------------------------------------------------
...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building Apache Accumulo Documentation 1.6.6-SNAPSHOT
[INFO] ------------------------------------------------------------------------
...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building Apache Accumulo Maven Plugin 1.6.6-SNAPSHOT
[INFO] ------------------------------------------------------------------------
...
[INFO]
[INFO] --- maven-compiler-plugin:3.3:compile (default-compile) @ accumulo-maven-plugin ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 4 source files to /Users/mjwall/NetBeansProjects/accumulo-mjwall/maven-plugin/target/classes
/Users/mjwall/NetBeansProjects/accumulo-mjwall/maven-plugin/target/generated-sources/plugin/org/apache/accumulo/maven/plugin/HelpMojo.java:100: warning: [Finally] If you return or throw from a finally, then values returned or thrown from the try-catch block will be ignored. Consider using try-with-resources instead.
throw new MojoExecutionException( e.getMessage(), e );
^
(see http://errorprone.info/bugpattern/Finally)
1 warning
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary:
[INFO]
[INFO] Apache Accumulo Project ............................ SUCCESS [ 3.028 s]
[INFO] Apache Accumulo Trace .............................. SUCCESS [ 1.216 s]
[INFO] Apache Accumulo Fate ............................... SUCCESS [ 0.584 s]
[INFO] Apache Accumulo Start .............................. SUCCESS [ 2.946 s]
[INFO] Apache Accumulo Core ............................... SUCCESS [ 28.759 s]
[INFO] Apache Accumulo Simple Examples .................... SUCCESS [ 1.099 s]
[INFO] Apache Accumulo Server Base ........................ SUCCESS [ 1.251 s]
[INFO] Apache Accumulo GC Server .......................... SUCCESS [ 0.856 s]
[INFO] Apache Accumulo Master Server ...................... SUCCESS [ 0.993 s]
[INFO] Apache Accumulo Monitor Server ..................... SUCCESS [ 1.111 s]
[INFO] Apache Accumulo Tracer Server ...................... SUCCESS [ 0.808 s]
[INFO] Apache Accumulo Tablet Server ...................... SUCCESS [ 1.032 s]
[INFO] Apache Accumulo MiniCluster ........................ SUCCESS [ 2.017 s]
[INFO] Apache Accumulo Native Libraries ................... SUCCESS [ 1.591 s]
[INFO] Apache Accumulo Testing ............................ SUCCESS [ 3.486 s]
[INFO] Apache Accumulo Proxy .............................. SUCCESS [ 1.984 s]
[INFO] Apache Accumulo .................................... SUCCESS [ 2.274 s]
[INFO] Apache Accumulo Documentation ...................... SUCCESS [ 0.280 s]
[INFO] Apache Accumulo Maven Plugin ....................... SUCCESS [ 6.065 s]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 01:02 min
[INFO] Finished at: 2016-03-03T11:05:24-05:00
[INFO] Final Memory: 142M/615M
[INFO] ------------------------------------------------------------------------
Notice the LongLiteralLowerCaseSuffix and NonOverridingEquals are both off. There were lots of these. Also notice I only ran 'mvn compile', there are errors in the test classes as well like
/Users/mjwall/NetBeansProjects/accumulo-mjwall/fate/src/test/java/org/apache/accumulo/fate/zookeeper/DistributedReadWriteLockTest.java:74: warning: [NonAtomicVolatileUpdate] This update of a volatile variable is non-atomic
++counter;
^
Maybe this is useful. Thanks to drew.farris for showing me error-prone.