[SPARK-11679][SQL] Invoking method " apply(fields:...

[SPARK-11679][SQL] Invoking method " apply(fields: java.util.List[StructField])" in "StructType" gets ClassCastException

In the previous method, fields.toArray will cast java.util.List[StructField] into Array[Object] which can not cast into Array[StructField], thus when invoking this method will throw "java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to [Lorg.apache.spark.sql.types.StructField;"
I directly cast java.util.List[StructField] into Array[StructField]  in this patch.

Author: mayuanwen <mayuanwen@qiyi.com>

Closes #9649 from jackieMaKing/Spark-11679.

sql/catalyst/src/main/scala/org/apache/spark/sql/types/StructType.scala

@@ -328,7 +328,8 @@ object StructType extends AbstractDataType {
   def apply(fields: Seq[StructField]): StructType = StructType(fields.toArray)
 
   def apply(fields: java.util.List[StructField]): StructType = {
-    StructType(fields.toArray.asInstanceOf[Array[StructField]])
+    import scala.collection.JavaConverters._
+    StructType(fields.asScala)
   }
 
   protected[sql] def fromAttributes(attributes: Seq[Attribute]): StructType =

sql/core/src/test/java/test/org/apache/spark/sql/JavaDataFrameSuite.java

@@ -22,6 +22,7 @@ import java.util.Arrays;
 import java.util.Comparator;
 import java.util.List;
 import java.util.Map;
+import java.util.ArrayList;
 
 import scala.collection.JavaConverters;
 import scala.collection.Seq;
@@ -209,6 +210,18 @@ public class JavaDataFrameSuite {
     Assert.assertEquals(1, result.length);
   }
 
+  @Test
+  public void testCreateStructTypeFromList(){
+    List<StructField> fields1 = new ArrayList<>();
+    fields1.add(new StructField("id", DataTypes.StringType, true, Metadata.empty()));
+    StructType schema1 = StructType$.MODULE$.apply(fields1);
+    Assert.assertEquals(0, schema1.fieldIndex("id"));
+
+    List<StructField> fields2 = Arrays.asList(new StructField("id", DataTypes.StringType, true, Metadata.empty()));
+    StructType schema2 = StructType$.MODULE$.apply(fields2);
+    Assert.assertEquals(0, schema2.fieldIndex("id"));
+  }
+
   private static final Comparator<Row> crosstabRowComparator = new Comparator<Row>() {
     @Override
     public int compare(Row row1, Row row2) {