[SPARK-6990][BUILD] Add Java linting script; fix minor warnings

This replaces https://github.com/apache/spark/pull/9696

Invoke Checkstyle and print any errors to the console, failing the step.
Use Google's style rules modified according to
https://cwiki.apache.org/confluence/display/SPARK/Spark+Code+Style+Guide
Some important checks are disabled (see TODOs in `checkstyle.xml`) due to
multiple violations being present in the codebase.

Suggest fixing those TODOs in a separate PR(s).

More on Checkstyle can be found on the [official website](http://checkstyle.sourceforge.net/).

Sample output (from [build 46345](https://amplab.cs.berkeley.edu/jenkins/job/SparkPullRequestBuilder/46345/consoleFull)) (duplicated because I run the build twice with different profiles):

> Checkstyle checks failed at following occurrences:
[ERROR] src/main/java/org/apache/spark/sql/execution/datasources/parquet/UnsafeRowParquetRecordReader.java:[217,7] (coding) MissingSwitchDefault: switch without "default" clause.
> [ERROR] src/main/java/org/apache/spark/sql/execution/datasources/parquet/SpecificParquetRecordReaderBase.java:[198,10] (modifier) ModifierOrder: 'protected' modifier out of order with the JLS suggestions.
> [ERROR] src/main/java/org/apache/spark/sql/execution/datasources/parquet/UnsafeRowParquetRecordReader.java:[217,7] (coding) MissingSwitchDefault: switch without "default" clause.
> [ERROR] src/main/java/org/apache/spark/sql/execution/datasources/parquet/SpecificParquetRecordReaderBase.java:[198,10] (modifier) ModifierOrder: 'protected' modifier out of order with the JLS suggestions.
> [error] running /home/jenkins/workspace/SparkPullRequestBuilder2/dev/lint-java ; received return code 1

Also fix some of the minor violations that didn't require sweeping changes.

Apologies for the previous botched PRs - I finally figured out the issue.

cr: JoshRosen, pwendell

> I state that the contribution is my original work, and I license the work to the project under the project's open source license.

Author: Dmitry Erastov <derastov@gmail.com>

Closes #9867 from dskrvk/master.

1 files changed, 30 insertions, 0 deletions

diff --git a/dev/lint-java b/dev/lint-java
new file mode 100755
index 0000000000..fe8ab83d56
--- /dev/null
+++ b/dev/lint-java
@@ -0,0 +1,30 @@
+#!/usr/bin/env bash
+
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You 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.
+#
+
+SCRIPT_DIR="$( cd "$( dirname "$0" )" && pwd )"
+SPARK_ROOT_DIR="$(dirname $SCRIPT_DIR)"
+
+ERRORS=$($SCRIPT_DIR/../build/mvn -Pkinesis-asl -Pyarn -Phive -Phive-thriftserver checkstyle:check | grep ERROR)
+
+if test ! -z "$ERRORS"; then
+    echo -e "Checkstyle checks failed at following occurrences:\n$ERRORS"
+    exit 1
+else
+    echo -e "Checkstyle checks passed."
+fi