scala

问题 I've got the answer on how to compare all attributes between two classes on this question, but my classes also have DateTime attributes that are defined on the fly, this way I cannot compare them because the DateTime on each class will have seconds of difference. How can I compare two classes attributes excluding some attributes? In this example, excluding the attribute z . case class Rect(x: Int, y: Int, z: Double) case class Squa(x: Int, y: Int, z: Double) 来源： https://stackoverflow.com

问题 I have abstract class A abstract class A{ def this(obj:Object){ this() obj match{ case s:String => stringMethod(s) case n:Int => intMethod(n) } def stringMethod(s:String) def intMethod(n:Int) } and I have a class that extends this class class B(obj:Object) extends A(obj){ var s:String = null def stringMethod(s:String){ this.s = s } def intMethod(n:Int){ this.s = n.toString } } The point of this class is to instantiate an object and its variables depending on the class type of the object used

问题 I have abstract class A abstract class A{ def this(obj:Object){ this() obj match{ case s:String => stringMethod(s) case n:Int => intMethod(n) } def stringMethod(s:String) def intMethod(n:Int) } and I have a class that extends this class class B(obj:Object) extends A(obj){ var s:String = null def stringMethod(s:String){ this.s = s } def intMethod(n:Int){ this.s = n.toString } } The point of this class is to instantiate an object and its variables depending on the class type of the object used

问题 According to this article here, when I create an aws emr cluster that will use spark to pipe data to dynamodb, I need to preface with the line: spark-shell --jars /usr/share/aws/emr/ddb/lib/emr-ddb-hadoop.jar This line appears in numerous references, including from the amazon devs themselves. However, when I run create-cluster with an added --jars flag, I get this error: Exception in thread "main" java.io.FileNotFoundException: File file:/usr/share/aws/emr/ddb/lib/emr-ddb-hadoop.jar does not

问题 I am working on the last project for the coursera course "functional programming in scala". I need to implement a function called combinations that takes a list of character occurrences and output all possible subsets of character occurrences. As an example, the subsets of the occurrence list List(('a', 2), ('b', 2)) are: List( List(), List(('a', 1)), List(('a', 2)), List(('b', 1)), List(('a', 1), ('b', 1)), List(('a', 2), ('b', 1)), List(('b', 2)), List(('a', 1), ('b', 2)), List(('a', 2), (

问题 Is there any way in scala/java to evaluate if all items in a JSON are not empty? I would like to have a validator, avoiding to have items in a json with empty values like: [{"elem1":"","elem2":"","elem3":"a"}] Where the first two elements are empty. 回答1: Using Play JSON: import play.api.libs.json._ def hasEmptyValue(json: JsValue): Boolean = { json match { case _: JsBoolean => false case _: JsNull => false // could also be true, depending on your definition case _: JsNumber => false case

问题 Is there any way in scala/java to evaluate if all items in a JSON are not empty? I would like to have a validator, avoiding to have items in a json with empty values like: [{"elem1":"","elem2":"","elem3":"a"}] Where the first two elements are empty. 回答1: Using Play JSON: import play.api.libs.json._ def hasEmptyValue(json: JsValue): Boolean = { json match { case _: JsBoolean => false case _: JsNull => false // could also be true, depending on your definition case _: JsNumber => false case

问题 Check below code. It is generating dataframe with ambiguity if duplicate keys are present . How should we modify the code to add parent column name as prefix to it. Added another column with json data. scala> val df = Seq( (77, "email1", """{"key1":38,"key3":39}""","""{"name":"aaa","age":10}"""), (78, "email2", """{"key1":38,"key4":39}""","""{"name":"bbb","age":20}"""), (178, "email21", """{"key1":"when string","key4":36, "key6":"test", "key10":false }""","""{"name":"ccc","age":30}"""), (179,

问题 Check below code. It is generating dataframe with ambiguity if duplicate keys are present . How should we modify the code to add parent column name as prefix to it. Added another column with json data. scala> val df = Seq( (77, "email1", """{"key1":38,"key3":39}""","""{"name":"aaa","age":10}"""), (78, "email2", """{"key1":38,"key4":39}""","""{"name":"bbb","age":20}"""), (178, "email21", """{"key1":"when string","key4":36, "key6":"test", "key10":false }""","""{"name":"ccc","age":30}"""), (179,

问题 class Person(name: String = "noname", age:Int = -1){} object ReflectionTester{ def main(args: Array[String]) { val m = ru.runtimeMirror(getClass.getClassLoader) val classTest = m.staticClass("Person") val theType = classTest.toType //class mirror val cm = m.reflectClass(classTest) val ctor = theType.decl(ru.termNames.CONSTRUCTOR).asMethod } } Invoking class mirror gives me the default constructor of passing name and age but there are inferred constructor too right where i can create a person