useful-kotlin-extensions

goto Function

This is simple an intuitive way to start a new activity
Place this code in a helper file

  fun Context.goto(javaClass: Class<*>) : Intent{
  val intent : Intent = Intent(this, javaClass)
  return intent
  }

  inline fun Intent.add (body: Intent.() -> Unit) { body() }

  fun Intent.start(context: Context){
  context.startActivity(this)
  }

and then you can do something like this

 context.goto(MyClass::class.java).add {
      addFlags(Intent.FLAG_ACTIVITY_NO_HISTORY)
      putExtra("ruleId", ruleId)
      putExtra("type", "Example")
      start(context)
 }

if you don't need to add flags or extras you can just do this

  context.goto(MyClass::class.java).start(context)

toPrefs function

This is a very simple way to put something into shared Preferences
I only have the int and String versions here but I'm sure you can work out how to get the other primitive types to work
Place this code in a helper file

fun Int.toPrefs(key: Int, context: Context){
    val s: String = context.resources.getString(key)
    val prefs = getDefaultSharedPreferences(context)
    prefs.edit().putInt(s, this).apply()
}

fun String.toPrefs(key: Int, context: Context){
    val s: String = context.resources.getString(key)
    val prefs = getDefaultSharedPreferences(context)
    prefs.edit().putString(s, this).apply()
}

Then all you need to do to put something into shared Preferences is:

   // for an integer
   5.toPrefs(R.string.key, context)

   // or if you have a var
   var myNumber = 0
   myNumber.toPrefs(R.string.key, context)

   // for a string
   "My string".toPrefs(R.string.key, context)
   
   // With a string var
   var myString = "My string"
   myString.toPrefs(R.string.key, context)

toast Function

A simple way to show toasts in Kotlin

  fun String.toast(context: Context)= Toast.makeText(context, this, Toast.LENGTH_SHORT).show()
  fun String.toastLong(context: Context) = Toast.makeText(context, this, Toast.LENGTH_LONG).show()

Then to show a toast

  "This is my toast".toast(context)
  
  val myString = "This is my toast"
  myString.toast(context)
  
  // or to show a long toast
  myString.toastLong(context)

forWith

This is a kotlin for loop with a with function

 inline fun <T> forWith(items: Iterable<T>, body: T.() -> Unit){
     for(item in items){
     item.body()
     }
 }

With this function you can do something like this:

  forWith (people) {
      hairColor = "blond"
      height = 5.12
      weight = 140
      age = 5
  }

instead of this

  for (person in people){
      person.hairColor = "blond"
      person.height = 5.12
      person.weight = 140
      person.age = 5       
  }