Jenkins pipeline, groovy map array as choises

Question

How can I pass the array variable into the global variable in groovy? It works perfectly without if-else.

choiceArray = []
if (appName == 'ms'){
                        ['78', '99', '10'].each {
                                        "${choiceArray}" << it
                        }
}
else if (appName == 'ms2'){
                        ['12', '34', '56'].each {
                                        "${choiceArray}" << it
                        }
}

  pipeline {
    parameters {
      string (name: 'Branch', defaultValue: 'master', description: 'Select Branch')
      choice(name: 'Environment', choices: choiceArray, description: 'Choose Environment')

Answer 1

if(...){
   choiceArray.addAll(['78', '99', '10'])
}