[jvm-packages] update checkstyle (#7335)

* [jvm-packages] update scalastyle

1. bump scalastyle-maven-plugin and maven-checkstyle-plugin to latest
2. remove unused imports

* fix code style check

jvm-packages/checkstyle.xml

@@ -64,6 +64,11 @@
         <property name="message" value="No trailing whitespace allowed."/>
     </module>
 
+    <module name="LineLength">
+        <property name="max" value="100"/>
+        <property name="ignorePattern" value="^package.*|^import.*|a href|href|http://|https://|ftp://"/>
+    </module>
+
     <module name="TreeWalker">
         <module name="OuterTypeFilename"/>
         <module name="IllegalTokenText">
@@ -77,11 +82,6 @@
             <property name="allowNonPrintableEscapes" value="true"/>
         </module>
         
-        <module name="LineLength">
-            <property name="max" value="100"/>
-            <property name="ignorePattern" value="^package.*|^import.*|a href|href|http://|https://|ftp://"/>
-        </module>
-        
         <module name="NoLineWrap"/>
         <module name="EmptyBlock">
             <property name="option" value="TEXT"/>

jvm-packages/pom.xml

@@ -385,7 +385,7 @@
             <plugin>
                 <groupId>org.scalastyle</groupId>
                 <artifactId>scalastyle-maven-plugin</artifactId>
-                <version>0.8.0</version>
+                <version>1.0.0</version>
                 <configuration>
                     <verbose>false</verbose>
                     <failOnViolation>true</failOnViolation>
@@ -413,7 +413,7 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-checkstyle-plugin</artifactId>
-                <version>2.17</version>
+                <version>3.1.2</version>
                 <configuration>
                     <configLocation>checkstyle.xml</configLocation>
                     <failOnViolation>true</failOnViolation>

jvm-packages/scalastyle-config.xml

@@ -48,21 +48,22 @@ This file is divided into 3 sections:
 
   <check level="error" class="org.scalastyle.file.HeaderMatchesChecker" enabled="true">
     <parameters>
-       <parameter name="header"><![CDATA[/*
+      <parameter name="regex">true</parameter>
-				  Copyright (c) 2014 by Contributors
+      <parameter name="header"><![CDATA[/\*
+ Copyright \(c\) \d{4}.* by Contributors
 
-					 Licensed under the Apache License, Version 2.0 (the "License");
+ Licensed under the Apache License, Version 2\.0 \(the "License"\);
-					  you may not use this file except in compliance with the License.
+ you may not use this file except in compliance with the License\.
-						 You may obtain a copy of the License at
+ You may obtain a copy of the License at
 
-						  http://www.apache.org/licenses/LICENSE-2.0
+ http://www\.apache\.org/licenses/LICENSE-2\.0
 
-							 Unless required by applicable law or agreed to in writing, software
+ Unless required by applicable law or agreed to in writing, software
-							  distributed under the License is distributed on an "AS IS" BASIS,
+ distributed under the License is distributed on an "AS IS" BASIS,
-								 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied\.
-								  See the License for the specific language governing permissions and
+ See the License for the specific language governing permissions and
-									 limitations under the License.
+ limitations under the License\.
-									  */]]></parameter>
+ \*/]]></parameter>
     </parameters>
   </check>
 

jvm-packages/xgboost4j-gpu/src/main/java/ml/dmlc/xgboost4j/gpu/java/CudfUtils.java

@@ -90,9 +90,9 @@ class CudfUtils {
       shapeNode.add(shape);
       ArrayNode dataNode = objNode.putArray("data");
       dataNode.add(ptr)
-        .add(false);
+          .add(false);
       objNode.put("typestr", typeStr)
-        .put("version", 1);
+          .put("version", 1);
       return objNode;
     }
   }

jvm-packages/xgboost4j-spark/src/main/scala/ml/dmlc/xgboost4j/scala/spark/DataUtils.scala

@@ -1,5 +1,5 @@
 /*
- Copyright (c) 2014 by Contributors
+ Copyright (c) 2014,2021 by Contributors
 
  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
@@ -21,10 +21,8 @@ import ml.dmlc.xgboost4j.{LabeledPoint => XGBLabeledPoint}
 import org.apache.spark.HashPartitioner
 import org.apache.spark.ml.feature.{LabeledPoint => MLLabeledPoint}
 import org.apache.spark.ml.linalg.{DenseVector, SparseVector, Vector, Vectors}
-import org.apache.spark.ml.param.Param
 import org.apache.spark.rdd.RDD
 import org.apache.spark.sql.{Column, DataFrame, Row}
-import org.apache.spark.sql.functions.col
 import org.apache.spark.sql.types.{FloatType, IntegerType}
 
 object DataUtils extends Serializable {

jvm-packages/xgboost4j-spark/src/main/scala/ml/dmlc/xgboost4j/scala/spark/XGBoost.scala

@@ -1,5 +1,5 @@
 /*
- Copyright (c) 2014 by Contributors
+ Copyright (c) 2014,2021 by Contributors
 
  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
@@ -32,7 +32,7 @@ import org.apache.commons.io.FileUtils
 import org.apache.commons.logging.LogFactory
 import org.apache.hadoop.fs.FileSystem
 import org.apache.spark.rdd.RDD
-import org.apache.spark.{SparkContext, SparkParallelismTracker, TaskContext, TaskFailedListener}
+import org.apache.spark.{SparkContext, SparkParallelismTracker, TaskContext}
 import org.apache.spark.sql.SparkSession
 import org.apache.spark.storage.StorageLevel
 

jvm-packages/xgboost4j-spark/src/main/scala/ml/dmlc/xgboost4j/scala/spark/XGBoostClassifier.scala

@@ -1,5 +1,5 @@
 /*
- Copyright (c) 2014 by Contributors
+ Copyright (c) 2014,2021 by Contributors
 
  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
@@ -26,7 +26,6 @@ import org.apache.spark.broadcast.Broadcast
 import org.apache.spark.ml.classification._
 import org.apache.spark.ml.linalg._
 import org.apache.spark.ml.param._
-import org.apache.spark.ml.param.shared.HasWeightCol
 import org.apache.spark.ml.util._
 import org.apache.spark.rdd.RDD
 import org.apache.spark.sql._

jvm-packages/xgboost4j-spark/src/main/scala/ml/dmlc/xgboost4j/scala/spark/XGBoostRegressor.scala

@@ -1,5 +1,5 @@
 /*
- Copyright (c) 2014 by Contributors
+ Copyright (c) 2014,2021 by Contributors
 
  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
@@ -19,7 +19,7 @@ package ml.dmlc.xgboost4j.scala.spark
 import scala.collection.{AbstractIterator, Iterator, mutable}
 import scala.collection.JavaConverters._
 
-import ml.dmlc.xgboost4j.java.{Rabit, XGBoost => JXGBoost}
+import ml.dmlc.xgboost4j.java.Rabit
 import ml.dmlc.xgboost4j.{LabeledPoint => XGBLabeledPoint}
 import ml.dmlc.xgboost4j.scala.spark.params.{DefaultXGBoostParamsReader, _}
 import ml.dmlc.xgboost4j.scala.{Booster, DMatrix, XGBoost => SXGBoost}
@@ -27,8 +27,7 @@ import ml.dmlc.xgboost4j.scala.{EvalTrait, ObjectiveTrait}
 import org.apache.hadoop.fs.Path
 
 import org.apache.spark.TaskContext
-import org.apache.spark.ml.linalg.{DenseVector, SparseVector, Vector}
+import org.apache.spark.ml.linalg.Vector
-import org.apache.spark.ml.param.shared.HasWeightCol
 import org.apache.spark.ml.util._
 import org.apache.spark.ml._
 import org.apache.spark.ml.param._
@@ -37,7 +36,6 @@ import org.apache.spark.sql._
 import org.apache.spark.sql.functions._
 import org.apache.spark.sql.types._
 import org.json4s.DefaultFormats
-import scala.collection.mutable.ListBuffer
 
 import org.apache.spark.broadcast.Broadcast
 

jvm-packages/xgboost4j-spark/src/main/scala/ml/dmlc/xgboost4j/scala/spark/params/CustomParams.scala

@@ -1,5 +1,5 @@
 /*
- Copyright (c) 2014 by Contributors
+ Copyright (c) 2014,2021 by Contributors
 
  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
@@ -22,7 +22,6 @@ import org.json4s.{DefaultFormats, Extraction, NoTypeHints}
 import org.json4s.jackson.JsonMethods.{compact, parse, render}
 
 import org.apache.spark.ml.param.{Param, ParamPair, Params}
-import org.apache.spark.sql.DataFrame
 
 class CustomEvalParam(
     parent: Params,

jvm-packages/xgboost4j-spark/src/main/scala/ml/dmlc/xgboost4j/scala/spark/params/GeneralParams.scala

@@ -1,5 +1,5 @@
 /*
- Copyright (c) 2014 by Contributors
+ Copyright (c) 2014,2021 by Contributors
 
  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
@@ -22,14 +22,6 @@ import ml.dmlc.xgboost4j.scala.spark.TrackerConf
 import org.apache.spark.ml.param._
 import scala.collection.mutable
 
-import ml.dmlc.xgboost4j.{LabeledPoint => XGBLabeledPoint}
-
-import org.apache.spark.ml.linalg.{DenseVector, SparseVector, Vector}
-import org.apache.spark.rdd.RDD
-import org.apache.spark.sql.{Column, DataFrame, Row}
-import org.apache.spark.sql.functions.col
-import org.apache.spark.sql.types.{FloatType, IntegerType}
-
 private[spark] trait GeneralParams extends Params {
 
   /**

jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/Booster.java

@@ -1,5 +1,5 @@
 /*
- Copyright (c) 2014 by Contributors
+ Copyright (c) 2014,2021 by Contributors
 
  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
@@ -436,7 +436,7 @@ public class Booster implements Serializable, KryoSerializable {
   }
 
   public String[] getModelDump(String[] featureNames, boolean withStats, String format)
-    throws XGBoostError {
+      throws XGBoostError {
     int statsFlag = 0;
     if (withStats) {
       statsFlag = 1;

jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/RabitTracker.java

@@ -1,7 +1,5 @@
 package ml.dmlc.xgboost4j.java;
 
-
-
 import java.io.*;
 import java.util.HashMap;
 import java.util.Map;
@@ -80,7 +78,7 @@ public class RabitTracker implements IRabitTracker {
   }
 
   public RabitTracker(int numWorkers)
-    throws XGBoostError {
+      throws XGBoostError {
     if (numWorkers < 1) {
       throw new XGBoostError("numWorkers must be greater equal to one");
     }