passing an array between classes

[gisler]

Hi,

Ok when i pass my array to another class it modifies the array. i am not sure why. I get the value of the array from a class and then i pass the value of the array to a different class. when i then modify the values in the class it changes the original values of the array. Hope that makes sense.

Many thanks

Gisler

[Supamagier]

It's probably because the array you think to modify actually points to the original array. What you should do is use a loop (or System.arraycopy) to copy all values in the original array to the array to be modified.

[CJSLMAN]

Couple of things...
First you say that you are passing an array between classes:

when i pass my array to another class it modifies the array

Then you say you are passing an array value between classes:

I get the value of the array from a class and then i pass the value of the array to a different class.

Which is it?
I would suggest you post some code showing what you are trying to do.

Luck,
CJSL

[kbindumadhavi]

when i then modify the values in the class it changes the original values of the array.

Gisler

Did you mean ...you are changing values of some other variables other than array or changing values of array?

[gisler]

Hi, thanks for the quick reply. Here is some of my code

randomNumbers = newGame.getarray(); //gets the array
totalGuesses++;
guessNumbers[0]= guessN1.getNumber();
guessNumbers[1]= guessN2.getNumber();
guessNumbers[2]= guessN3.getNumber();
guessNumbers[3]= guessN4.getNumber();
results = calculateGuess.getGuessresults(guessNumbers ,randomNumbers);
score=(results[2]/totalGuesses)+score;

the first line gets the values of the array and puts it into a new array called randomNumbers. I then pass the values of the array randomNumbers and guessNumbers to a new class called calculateGuess. The methods for that class is...

public int[] getGuessresults(int[] guessed,int [] randomNum)
{
results = calculateResults(guessed, randomNum);
return results;
}

private int[] calculateResults(int[] guesses,int[]randomNums)
{
//Edit the array here.

Thanks for your help.

gisler

[CJSLMAN]

I'm still fuzzy about were the problem is. What array elements get changed? Have you tried to debug the problem (with printlns)? If not, try putting printlns throughout your code so you can follow the flow of data and find where it's being changed.

Luck,
CJSL

[gisler]

the problem is when i change the values of the array in my calculateGuess class

private int[] calculateResults(int[] guesses,int[]randomNums)
{
//Edit the array here.

it also changes the values of the array in my newgame class.

randomNumbers = newGame.getarray(); //gets the array

I have tried debugging this load and can't figure it out. i think it might have something to do with making my methods or classes public when they should be private.

Many thanks
gisler

[kbindumadhavi]

Can you please specify where the values are getting changed in your main class?

[kbindumadhavi]

One more thing...you can directly call calculateResults() method from your main class as nothing is done in getGuessresults() except you are calling calculateResults() method.

[emceenugget]

It's probably because the array you think to modify actually points to the original array. What you should do is use a loop (or System.arraycopy) to copy all values in the original array to the array to be modified.

this. arrays are objects. therefore, when you pass it along, you pass a reference to the original array. it's behaving how it is meant to behave.

[gisler]

thanks emceenugget. that makes perfect sense. i will just copy the array to a new array and my problem should be solved. Also thanks Kbindumadhavi. I have gotten rid of the useless method.

Thanks eveyone else.

gisler