Java chatbot mirroring and canned responses

So I got this java chatbot program that I'm working on.

Depending on what the user says, the chatbot either gives a canned response canned_phrases or a mirrored response if the user's response has one of the keywords I love pizza --> you love pizza.

The problem is that the chatbot does not give back the mirrored version. I think the problem is that the words are being overwritten by each other but I'm not sure how to fix that.

Thank for your help!

import java.util.Random;
import java.util.Scanner;

public class Conversation {

    public static void main(String[] args) {
        String[] canned_phrases = {"Yes",
                                   "Hmmm. Please tell me more news",
                                   "Of course",
                                   "Okay",
                                   "Interesting...",
                                   "Indeed"};
        int canned_times = canned_phrases.length;

        Scanner conversation_start = new Scanner(System.in);
        System.out.println("\nWelcome!\n");
        System.out.println("How many rounds of conversation would you like to have?\n");
        int rounds = conversation_start.nextInt();
        conversation_start.nextLine();
        String[] transcript = new String[2 * rounds + 1];
        transcript[0] = "Sounds great! How are you doing today?";
        System.out.println(transcript[0]);
        for (int i = 0; i < rounds; i++) {
            String user_words = conversation_start.nextLine();
            String mirrored;
            String new_version = user_words.replace("I", "you");
            new_version = new_version.replace("me", "you");
            new_version = new_version.replace("am", "are");
            new_version = new_version.replace("you", "I");
            new_version = new_version.replace("my", "your");
            new_version = new_version.replace("your", "my");
            new_version = new_version.replace("my", "you");
            if (!new_version.equals(user_words)) {
                mirrored = new_version;
            }
            else {
                mirrored = canned_phrases[(int) Math.floor(canned_times * Math.random())];
            }
            System.out.println(mirrored);
            transcript[2 * i + 1] = user_words;
            transcript[2 * i + 1] = mirrored;
        }
        System.out.println("Thank you for chatting with me! Come back soon!");
        System.out.println(" ");
        System.out.println("TRANSCRIPT ");
        for (int i = 0; i <= transcript.length; i++) {
            System.out.println(transcript[i]);
        }
        System.exit(0);
    }
}

I think the best way to achieve what you want is to split the user-entered sentence into words and change the individual words according to your rules, for example if the word is my then change it to your. In the below code, I iterate through all the words in order, changing each word as needed and appending them to a StringBuilder so that after iterating through all the words, the StringBuilder contains the mirrored sentence.

(More notes after the code.)

import java.util.Random;
import java.util.Scanner;

public class Conversation {

    public static void main(String[] args) {
        String[] cannedPhrases = {"Yes",
                                  "Hmmm. Please tell me more news",
                                  "Of course",
                                  "Okay",
                                  "Interesting...",
                                  "Indeed"};
        int cannedTimes = cannedPhrases.length;
        Random rand = new Random();
        Scanner conversationStart = new Scanner(System.in);
        System.out.println("\nWelcome!\n");
        System.out.println("How many rounds of conversation would you like to have?\n");
        int rounds = conversationStart.nextInt();
        conversationStart.nextLine();
        String[] transcript = new String[2 * rounds];
        transcript[0] = "Sounds great! How are you doing today?";
        System.out.println(transcript[0]);
        int index = -1;
        for (int i = 0; i < rounds; i++) {
            String userWords = conversationStart.nextLine();
            String mirrored;
            StringBuilder result = new StringBuilder();
            String[] words = userWords.split(" ");
            boolean first = true;
            for (String word : words) {
                if (first) {
                    first = false;
                }
                else {
                    result.append(' ');
                }
                switch (word) {
                    case "I":
                        word = "you";
                        break;
                    case "me":
                        word = "you";
                        break;
                    case "am":
                        word = "are";
                        break;
                    case "you":
                        word = "I";
                        break;
                    case "my":
                        word = "your";
                        break;
                    case "your":
                        word = "my";
                        break;
                }
                result.append(word);
            }
            String newVersion = result.toString();
            if (!newVersion.equals(userWords)) {
                mirrored = newVersion;
            }
            else {
                mirrored = cannedPhrases[rand.nextInt(cannedTimes)];
            }
            System.out.println(mirrored);
            transcript[++index] = userWords;
            transcript[++index] = mirrored;
        }
        System.out.println("Thank you for chatting with me! Come back soon!");
        System.out.println(" ");
        System.out.println("TRANSCRIPT ");
        for (int i = 0; i < transcript.length; i++) {
            System.out.println(transcript[i]);
        }
        System.exit(0);
    }
}

• You should try to adhere to Java naming conventions. I changed the variable names in your code accordingly.
• Rather than manipulate the [first] for loop variable i to handle both the conversation round and the transcript index, I used a separate variable, named index for the transcript.
• Switching on string was added in Java 7.
• The for loop that prints the transcript was wrong. The terminating condition should be i < transcript.length (and not i <= transcript.length).
• The above code assumes that the user-entered sentence consists of words separated by single spaces. If you want more sophisticated handling of the user-entered sentence, for example handling punctuation, like commas, periods, etc, then you will need to change the split method's regular expression.

Here is output from a sample run:

Welcome!

How many rounds of conversation would you like to have?

2
Sounds great! How are you doing today?
OK
Of course
Why do you say that
Why do I say that
Thank you for chatting with me! Come back soon!
 
TRANSCRIPT 
OK
Of course
Why do you say that
Why do I say that