Android Studio Java - How do I use a random array without repeating?

Question

I've got an array of random messages, but I want it so that it doesn't pick a message that has already been picked and then reset once all messages have been picked.

public void showRandomMsg(){
        shuffleMsg();
        answer1.setText((messageArray[0].getmAns()));
        message2.setText((messageArray[0].getmMsg()));
        toyView1.setImageResource(messageArray[0].getmImage());
    }

Messages m01 = new Messages(R.drawable.crown1, "Mesage 0 A","Message 0 B");
Messages m02 = new Messages(R.drawable.crown2,"Mesage 1 A","Message 1 B");
Messages m03 = new Messages(R.drawable.crown3,"Mesage 2 A","Message 2 B");
Messages m04 = new Messages(R.drawable.crown4,"Mesage 3 A","Message 3 B");
Messages m05 = new Messages(R.drawable.crown5,"Mesage 4 A","Message 4 B");

Messages [] messageArray=new Messages[]{
        m01, m02, m03, m04, m05
};

public void shuffleMsg(){
    Collections.shuffle(Arrays.asList(messageArray));

}

For non-repetition you could shuffle the message array and work through the shuffled array in order. Only reshuffle when you have used all the messages. — rossum
– rossum, Commented Dec 23, 2020 at 12:53

Tim Biegeleisen · Accepted Answer · 2020-12-23 02:22:38Z

4

You could write logic for the message getter which removes one message, and in the event that no message be available, repopulates:

List<Messages> messageList;

public void showRandomMsg(){
    if (Objects.isNull(messageList) || messageList.size() == 0) {
        refillMsg();
    }
    answer1.setText(messageList.remove(0).getmAns());
    message2.setText(messageList.remove(0).getmMsg());
    toyView1.setImageResource(messageList.remove(0).getmImage());
}

public void refillMsg() {
    messageList = Arrays.asList(new Messages[] {
        m01, m02, m03, m04, m05
    });
    Collections.shuffle(messageList);
}

answered Dec 23, 2020 at 2:22

Tim Biegeleisen

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1 Comment

Areki Over a year ago

Hi Tim, thanks a lot, this is actually an elegant way of doing it!

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