global arrays

[Yahel Perman]

Hello,

i have an int array for example :  arr = {10,13,23,14}.

I want to shuffle the numbers of arr and put it in arr2. (so for example the arr2 = {23,13,10,14}

then i want to use the arr2[0] , arr2[1] in any other class i want.

Basically i dont want to use the same number twice.

Is it possible?

[Stephan van Hulst]

Welcome to CodeRanch!

Sure, it's possible. What have you tried? What are you stuck on?

[Norm Radder]

Are the other classes in the same activity with the array?

[Yahel Perman]

Hello again and thanks for your replies.

Im creating a multiple choice quiz game and i want to shuffle the answers.
Currently my code is like this

button1 {
   string aChoice0 = aChoices [a][0];
}

where [a] is the array with questions and [0] is the position of the answers array

so i want the shuffling array to be outside the button class.
Ideally i want something like.

button1 {
   string aChoice0 = aChoices [a][shuffle.array[0]];
}

where the shuffle.array[0] will be a shuffled array of integers

[Campbell Ritchie]

Welcome to the Ranch

Please indent your code and use the code button; I went back to your code and added code tags and doesn't it look better now

Beware of passing arrays around. Arrays in Java® are always mutable and all it takes is one line of code saying myArray[i] = xyz; and you have broken your code everywhere you are using that array. You can copy arrays with their clone() method.
I don't know of a shuffling technique readily available in Java® (Android might be different) but you can shuffle Lists (link) or you can copy that technique to write your own shuffle() method.

[Yahel Perman]

Thanks again!

Im using the collection.shuffle or the Fisher-Yates shuffle directly. The problem is that, if i call the shuffle() method inside the buttons class, reshuffles the answers everytime with result to have same answers in different buttons. Thats why i need to shuffle the array once (outside the button classes or maybe in different .java file) and then call the shuffled array indices one by one.

like

shuffle.java

public class shuffle{ 
array = {1,2,3,4};
shuffledArray = collection.shuffle(array);

buttons.java

button1 {
achoice = aChoices [shuffleArray[0]
}

[Campbell Ritchie]

Your shuffle technique doesn't shuffle the array everywhere. If you only use one array and don't take copies of it, you only have one array and it has the same state everywhere. Not, “shuffle everywhere,” but, “shuffle once, see the result everywhere.” You need to take copies of the array wherever you use it.

[Yahel Perman]

Right now im not in frond of my working PC so i cant test it.

But as i understand, you suggest shuffling the array inside the first button class, and then using the copy.array[1] inside the second button class?

[Campbell Ritchie]

Is that what you want? I would have thought take a copy of thee original array and shuffle the copy. Each object getting an array should copy it immediately. That way everywhere the array is used has its own copy and they will behave as independent of one another. The problem with global variables is that changes made to them are reflected everywhere.