Random sentence generator returning numbers and not sentence

I am suppose to create a random sentence generator. I have done everything but when I run a test, instead of returning a sentence it returns a number.

Ex: If it should return "A beautiful car explodes.", returns 0100. instead.

I am pretty sure I am missing something but at this point I cannot figure it out. I believe my test is written wrong, but I am not sure. Any help would be appreciated. Thank you!

public class set2{

 public static void main(String[] args) {

    String[] article = new String[4];
    String[] adj = new String[2];
    String[] noun = new String[2];
    String[] verb = new String[3];

    article[0] = "A";
    article[1] = "The";
    article[2] = "One";
    article[3] = "That";

    adj[0] = "hideous";
    adj[1] = "beautiful";

    noun[0] = "car";
    noun[1] = "woman";

    verb[0] = "explodes";
    verb[1] = "is dying";
    verb[2] = "is moving";

    // Test for randomSentence
    System.out.println(randomSentence(article, adj, noun, verb));

  public static String randomSentence(String[] article, String[] adj, String[] noun, String[] verb) {

    Random rand = new Random();

    int articledx = rand.nextInt(article.length);
    int adjdx = rand.nextInt(adj.length);
    int noundx = rand.nextInt(noun.length);
    int verbdx = rand.nextInt(verb.length);

    String sentence = articledx + "" + adjdx + "" + noundx + "" + verbdx + ".";

    return sentence;