HELP - How to get a random string item from list

[d0t (Mike)]

Hello,

I’m trying to get a random string from a list of quotes defined inside of an OpenHAB rule, and having difficulty understanding how to do it. I’ve tried a variety of seemingly standard java ways to do this, but to no avail; must be missing something. For instance, lets say we’re working with the following rule:

rule "VoiceCMD"
when
  Item VoiceCMD received update
then
  var String voicecmd = VoiceCMD.state.toString.toLowerCase   
    if (voicecmd.contains('say a quote')) {
    	var Quotes = newArrayList(
				"Power to four-hundred percent capacity.",
				"You are malfunctioning.",
				"You are in distress.",
				"I believe your intentions to be hostile.",
				"Sir, I think I need to sleep now..."
				)
    Random r = new Random()
    var msg = r.nextInt(Quotes.length)
    sendCommand(VoiceCMD_Response, msg)
    }
end

In this example, ‘Random r’ throws errors in OpenHAB Designer and everything below it does not work. How can we access a random string value from the list, to set ‘var msg’ before calling the SendCommand()?

Thanks in advance for any assistance…

.

[samverner777 (Joel)]

i think you only need to include random or use the complete path.

check this post:

[solved] Random numbers not so random? (new java.util.Random).nextInt

This has to do with how Random number generators work. They use an equation that generates a pseudorandom sequence using a formula. But that formula needs a seed value to get started. If you give it the same seed it will produce the same sequence of numbers every time. By creating a new Random object every time you need a number you are relying on what ever mechanism Random uses to generate a seed when you don’t provide one for it (probably based on the time of day or something like that). I’m …

[d0t (Mike)]

@samverner777 - thanks for that! I had already included the global ‘import java.util.Random’, and had also briefly looked at the ‘val’ approach. This (linked) approach seemingly works for random integers but I’m still at a loss to get this working for random strings from a list. (also attempted this further per your suggestion!) Guessing I need to use the int to select the list value by key/id, but don’t understand the DSL syntax well enough, yet

.

[rlkoshak (Rich Koshak)]

@d0t

Guessing I need to use the int to select the list value by key/id, but don’t understand the DSL syntax well enough, yet

Correct. Create an ArrayList with your Strings, or a HashMap, though an ArrayList is probably more appropriate.

Use the random number generator to create a number between 0 and the number of items in your list. Then call myList.get(rndm) where myList is the list with Strings in it and rndm is your randomly generated Int.

[d0t (Mike)]

Thanks all for the help. Here is my working solution for getting a random string from the Array!

val java.util.Random rand = new java.util.Random
	
rule "VoiceCMD"
when
  Item VoiceCMD received update
then
  var String voicecmd = VoiceCMD.state.toString.toLowerCase   
  if (voicecmd.contains('say a quote')) {
    	var Quotes = newArrayList(
				"Power to four-hundred percent capacity.",
				"You are malfunctioning.",
				"You are in distress.",
				"I believe your intentions to be hostile.",
				"Sir, I think I need to sleep now..."
				)
        var i = rand.nextInt(5);
        var msg = Quotes.get(i)
        sendCommand(VoiceCMD_Response, msg)
  }
end

Best regards,
.