[SPARK-6428] Turn on explicit type checking for public methods.

This builds on my earlier pull requests and turns on the explicit type checking in scalastyle.

Author: Reynold Xin <rxin@databricks.com>

Closes #5342 from rxin/SPARK-6428 and squashes the following commits:

7b531ab [Reynold Xin] import ordering
2d9a8a5 [Reynold Xin] jl
e668b1c [Reynold Xin] override
9b9e119 [Reynold Xin] Parenthesis.
82e0cf5 [Reynold Xin] [SPARK-6428] Turn on explicit type checking for public methods.

5 files changed, 6 insertions, 5 deletions

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/AnalysisException.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/AnalysisException.scala
index 34fedead44..f9992185a4 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/AnalysisException.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/AnalysisException.scala
@@ -30,7 +30,7 @@ class AnalysisException protected[sql] (
     val startPosition: Option[Int] = None)
   extends Exception with Serializable {
 
-  def withPosition(line: Option[Int], startPosition: Option[Int]) = {
+  def withPosition(line: Option[Int], startPosition: Option[Int]): AnalysisException = {
     val newException = new AnalysisException(message, line, startPosition)
     newException.setStackTrace(getStackTrace)
     newException
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/package.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/package.scala
index c61c395cb4..7731336d24 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/package.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/package.scala
@@ -44,7 +44,7 @@ package object analysis {
   }
 
   /** Catches any AnalysisExceptions thrown by `f` and attaches `t`'s position if any. */
-  def withPosition[A](t: TreeNode[_])(f: => A) = {
+  def withPosition[A](t: TreeNode[_])(f: => A): A = {
     try f catch {
       case a: AnalysisException =>
         throw a.withPosition(t.origin.line, t.origin.startPosition)
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/sources/ddl.scala b/sql/core/src/main/scala/org/apache/spark/sql/sources/ddl.scala
index eb46b46ca5..319de710fb 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/sources/ddl.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/sources/ddl.scala
@@ -204,7 +204,7 @@ private[sql] object ResolvedDataSource {
       provider: String,
       options: Map[String, String]): ResolvedDataSource = {
     val clazz: Class[_] = lookupDataSource(provider)
-    def className = clazz.getCanonicalName
+    def className: String = clazz.getCanonicalName
     val relation = userSpecifiedSchema match {
       case Some(schema: StructType) => clazz.newInstance() match {
         case dataSource: SchemaRelationProvider =>
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveMetastoreCatalog.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveMetastoreCatalog.scala
index c4da34ae64..ae5ce4cf4c 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveMetastoreCatalog.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveMetastoreCatalog.scala
@@ -861,7 +861,7 @@ private[hive] case class MetastoreRelation
   /** An attribute map for determining the ordinal for non-partition columns. */
   val columnOrdinals = AttributeMap(attributes.zipWithIndex)
 
-  override def newInstance() = {
+  override def newInstance(): MetastoreRelation = {
     MetastoreRelation(databaseName, tableName, alias)(table, partitions)(sqlContext)
   }
 }
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveQl.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveQl.scala
index 5be09a11ad..077e64133f 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveQl.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveQl.scala
@@ -659,7 +659,8 @@ https://cwiki.apache.org/confluence/display/Hive/Enhanced+Aggregation%2C+Cube%2C
                   AttributeReference("value", StringType)()), true)
             }
 
-            def matchSerDe(clause: Seq[ASTNode]) = clause match {
+            def matchSerDe(clause: Seq[ASTNode])
+              : (Seq[(String, String)], String, Seq[(String, String)]) = clause match {
               case Token("TOK_SERDEPROPS", propsClause) :: Nil =>
                 val rowFormat = propsClause.map {
                   case Token(name, Token(value, Nil) :: Nil) => (name, value)