[SPARK-22452][SQL] Add getDouble to DataSourceV2Options

- Implemented getDouble method in DataSourceV2Options
- Add unit test

Author: Sunitha Kambhampati <[email protected]>

Closes #19921 from skambha/ds2.

Author: skambha

sql/core/src/main/java/org/apache/spark/sql/sources/v2/DataSourceV2Options.java

@@ -80,4 +80,13 @@ public long getLong(String key, long defaultValue) {
       Long.parseLong(keyLowerCasedMap.get(lcaseKey)) : defaultValue;
   }
 
+  /**
+   * Returns the double value to which the specified key is mapped,
+   * or defaultValue if there is no mapping for the key. The key match is case-insensitive
+   */
+  public double getDouble(String key, double defaultValue) {
+    String lcaseKey = toLowerCase(key);
+    return keyLowerCasedMap.containsKey(lcaseKey) ?
+      Double.parseDouble(keyLowerCasedMap.get(lcaseKey)) : defaultValue;
+  }
 }

sql/core/src/test/scala/org/apache/spark/sql/sources/v2/DataSourceV2OptionsSuite.scala

@@ -68,4 +68,15 @@ class DataSourceV2OptionsSuite extends SparkFunSuite {
       options.getLong("foo", 0L)
     }
   }
+
+  test("getDouble") {
+    val options = new DataSourceV2Options(Map("numFoo" -> "922337.1",
+      "foo" -> "bar").asJava)
+    assert(options.getDouble("numFOO", 0d) == 922337.1d)
+    assert(options.getDouble("numFoo2", -1.02d) == -1.02d)
+
+    intercept[NumberFormatException]{
+      options.getDouble("foo", 0.1d)
+    }
+  }
 }