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I'm experiencing a pretty strange thing in Kotlin. I have
var myClipboard = getSystemService(CLIPBOARD_SERVICE) as ClipboardManager? var myClip: ClipData? = ClipData.newPlainText( /* my code */ ) As a var variable, I should be able to reassign his value, but when I do
myClipboard?.primaryClip = myClip It gives me the error
Val cannot be reassigned
The strangest things is that I'm using this code by weeks and it always worked. It stopped working today when I updated to API 29
This is my build.gradle android{}
android { compileSdkVersion 29 defaultConfig { applicationId "com.arfmann.pushnotes" minSdkVersion 23 targetSdkVersion 29 versionCode 16 versionName "1.6" testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner" } buildTypes { release { minifyEnabled true proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro' } } } 
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A variable declared with `var` is mutable. A variable declared with `val` is immutable. A variable declared with `const` is immutable. Values are assigned at run time. Values are assigned at run time.
Read-only local variables are defined using the keyword val . They can be assigned a value only once. Variables that can be reassigned use the var keyword. You can declare variables at the top level.
Kotlin uses two different keywords to declare variables: val and var . Use val for a variable whose value never changes. You can't reassign a value to a variable that was declared using val . Use var for a variable whose value can change.
Kotlin, the language itself, encourages developers to write immutably, by encouraging you to use val . The result is code that literally looks cleaner. Using vals in your code makes you think about alternative, immutable, functional code.
As seen in the ClipboardManager documentation, getPrimaryClip returns a ClipData? (i.e., a nullable ClipData) while setPrimaryClip() takes a ClipData - a non-null ClipData.
Kotlin does not support var property access when the types are different (and nullability is an important part of Kotlin typing) therefore Kotlin can only give you effectively the val equivalent when you call primaryClip.
The nullability annotation on setPrimaryClip was added in API 29, which is why the behavior is different once you upgrade your compileSdkVersion.
To set the primary clip, you must explicitly use setPrimaryClip() with a non-null ClipData or, on API 28+, use clearPrimaryClip() to completely clear the primary clip.
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