kotlin

问题 I am trying to call the following Kotlin function from Java override fun First(list: LinqList<ElementType>, condition: (ElementType) -> Boolean) : ElementType like this int first = list.First(list,(x) -> x == 5); but i get the following error Error java: cannot access kotlin.jvm.functions.Function1 class file for kotlin.jvm.functions.Function1 not found I have tried googling it but i can not find the answer anywhere Thanks in advance 回答1: My problem got fixed when I configured Kotlin compiler

问题 I do not know how to implement a filter query properly inside the Repository and the ViewModel to use it to display the filtered string in a Textview or anything else really. My Entity, Dao, Repository, and ViewModel are as follows: User.kt @Entity(tableName = "user_data") data class User ( @PrimaryKey(autoGenerate = true) val id: Int, @ColumnInfo(name = "name") val name: String ) UserDao.kt @Dao interface UserDao { @Insert fun addUser(user: User) @Query("SELECT name FROM user_data WHERE name

问题 I'm trying to show call logs from Sim1 and Sim2 separately. I'm getting all call logs, but not able to differentiate it whether it is from Sim1 or Sim2. I have tried below code, val managedCursor = activity?.contentResolver?.query(CallLog.Calls.CONTENT_URI, null, null, null, null) managedCursor?.let { val number = managedCursor.getColumnIndex(CallLog.Calls.NUMBER) val name = managedCursor.getColumnIndex(CallLog.Calls.CACHED_NAME) val type = managedCursor.getColumnIndex(CallLog.Calls.TYPE) val

问题 I need leave something to do later on my code and TODO() auto generated produces a very long comment like follow TODO("not implemented") //To change body of created functions use File | Settings | File Templates. The above line tell me to go to File -> Setting -> File Template to change it, but this option not exists to TODO() functions. How to solve it? 回答1: Go to the Preferences window in Android Studio, select Editor -> File and Code Templates , open the Code tab, there you will find an

问题 As explained in some answers: On Android, Firebase automatically manages connection state to reduce bandwidth and battery usage. When a client has no active listeners, no pending write or onDisconnect operations, and is not explicitly disconnected by the goOffline method, Firebase closes the connection after 60 seconds of inactivity. The problem is that after 60s, even after I go to an activity with a complete new reference, event listener, etc.. It still says it is disconnect, when in fact,

问题 As explained in some answers: On Android, Firebase automatically manages connection state to reduce bandwidth and battery usage. When a client has no active listeners, no pending write or onDisconnect operations, and is not explicitly disconnected by the goOffline method, Firebase closes the connection after 60 seconds of inactivity. The problem is that after 60s, even after I go to an activity with a complete new reference, event listener, etc.. It still says it is disconnect, when in fact,

问题 What is the main difference in these two: val array: Array<Double> = arrayOf() vs val array: DoubleArray = doubleArrayOf() I know that one is using primitive data type double and the second its object based countrepart Double . Is there any penalty or disadvatnage in using plain DoubleArray ? Why I want to know: I am using JNI and for Double , I have to call jclass doubleClass = env->FindClass("java/lang/Double"); jmethodID doubleCtor = env->GetMethodID(doubleClass, "<init>", "(D)V");

问题 I am listing all my media files in a recycler view. Suppose a media file is in a folder, then I want to show that folder in my recycler view too. Here is my code to list media files var projection = arrayOf(MediaStore.Video.Media.DISPLAY_NAME) var cursor = CursorLoader(applicationContext, MediaStore.Video.Media.EXTERNAL_CONTENT_URI, projection, null, null, null).loadInBackground() if (cursor != null) { while (cursor.moveToNext()) { val name = cursor.getString(cursor.getColumnIndex(MediaStore

问题 I am listing all my media files in a recycler view. Suppose a media file is in a folder, then I want to show that folder in my recycler view too. Here is my code to list media files var projection = arrayOf(MediaStore.Video.Media.DISPLAY_NAME) var cursor = CursorLoader(applicationContext, MediaStore.Video.Media.EXTERNAL_CONTENT_URI, projection, null, null, null).loadInBackground() if (cursor != null) { while (cursor.moveToNext()) { val name = cursor.getString(cursor.getColumnIndex(MediaStore

问题 I want to convert a date string to unix timestamp from a date string e.g. 14-02-2018 Can someone help? 回答1: Since JDK 8 you can do: val l = LocalDate.parse("14-02-2018", DateTimeFormatter.ofPattern("dd-MM-yyyy")) val unix = l.atStartOfDay(ZoneId.systemDefault()).toInstant().epochSecond Note that the example uses your system's default timezone. 回答2: use this to convert the date string to UNIX timestamp val date = SimpleDateFormat("dd-MM-yyyy").parse("14-02-2018") println(date.time) 来源： https:/