Solution for RandomStringChooser FRQ from 2016

ClientCode.java

String[] wordArray = {"wheels", "on", "the", "bus"};
RandomStringChooser sChooser = new RandomStringChooser(wordArray);
for (int k = 0; k < 6; k++) {
  System.out.print(sChooser.getNext() + " "); 
}

// Possible output
// bus the wheels on NONE NONE

ClientCode_Letter.java

RandonLetterChooser letterChooser = new RandomLetterChooser("cat");
for (int k=0; k<4; k++) {
  System.out.print(letterChooser.getNext()); 
}

// Possible output
// actNONE

RandomLetterChooser.java

public class RandomLetterChooser extends RandomStringChooser {

    public RandomLetterChooser( String str ) {
        super( getSingleLetters( str ) );
    }

    public static String[] getSingleLetters( String str ) {
        String[] out = new String[str.length()];
        
        for (int i=0; i<str.length(); i++) {
            out[i] = str.substring(i, i+1); 
        }
        
        return out; 
    }

}

RandomLetterChooser_Starter.java

public class RandomLetterChooser extends RandomStringChooser {
  public RandomLetterChooser(String str) {
    // To be implemented in Part (B) 
  }
  
  public static String[] getSingleLetters(String str) {
    // Implementation not shown 
  }
}

RandomStringChooser.java

import java.util.ArrayList;

public class RandomStringChooser {

    private ArrayList<String> wordList;

    public RandomStringChooser( String[] words ) {
        wordList = new ArrayList<>();

        for ( String word : words ) {
            wordList.add( word );
        }

    }

    public String getNext() {
        if ( wordList.size() == 0 ) {
            return "NONE";
        }

        int rnd = (int)(Math.random() * wordList.size());
        
        return wordList.remove( rnd ); 
        
    }

}