Thread: Function that compares two arrays and stores the result in a third one

Hello, I'm really new to Java. I have to do an exercice where a function compares two String arrays (one randomly generated by the computer and the other chosen by the user. And each time it finds an identical element, it puts it in a third array that's String too. The problem is that the main totally ignore the function and doesn't want to call her. And I got this error message :
(in thread "main" java.lang.NullPointerException
at Mastermind_ho.compareColor(Mastermind_ho.java:80)
at Mastermind_ho.main(Mastermind_ho.java:31))

I did this (I post the main as well as the function in question, to lighten I'm not posting the random function unless it's necessary). Thank you in adavnce

--------------- the main
import java.util.Scanner;
public class Mastermind_ho {
static Scanner sc = new Scanner(System.in);
static String [] TAB_REF_COLORS = {"rouge","jaune","vert","bleu","orange","blanc","v iolet","fuchsia"};
static int NB_COLORS = 4;
static int compteur=0;
static String [] combination;
static String [] tabJoueur;
static String [] tabCorrect= {" "," "," "," "};

public static void main(String[] args) {

String [] combinaisonSecrete = generateRandomCombination();
for(int i=0;i<4;i++) {
System.out.print(combinaisonSecrete[i]+ "|");
}
String [] combinaisonJoueur;
System.out.println();
do {
combinaisonJoueur = choixNumerote();
for(int i=0;i<4;i++) {
System.out.print(combinaisonJoueur[i]+ "|");
}
//??
}while (compteur<=12 && (12-compteur)>0);

compareColor (tabJoueur, combination);
for(int k=0;k<4;k++) {
System.out.print(tabCorrect[k]+ "|");
}

sc.close();
}

--------------- the function

static void compareColor (String [] tabPlayer, String [] tabOrdi) {
int sizeTj = tabPlayer.length;
int sizeTm = tabOrdi.length;
int k=0;
for (int i=0;i<sizeTj;i++) {
for(int j=0; j<sizeTm; j++) {
if (tabOrdi[j]==tabPlayer[i]) {
System.out.print("Vous avez trouver une couleur");
tabCorrect[k]=tabOrdi[j];
k++;
}
else {
continue;
}
}
}

Are you talking about tabPlayer? if that's the case the

static void compareColor (String [] tabPlayer, String [] tabOrdi

) has got 2 arguments and the function in the main that calls it has also 2 arguments compareColor (tabJoueur, combination); and both of them have returned value : return tabJoueur; and return combination. So, I don't understand why they have null value then?

The entire code :

import java.util.Scanner;
public class Mastermind_ho {
 
static Scanner sc = new Scanner(System.in);
static String [] TAB_REF_COLORS = {"rouge","jaune","vert","bleu","orange","blanc","violet","fuchsia"};
static int NB_COLORS = 4;
static int compteur=0;
static String [] combination;
static String [] tabJoueur;
static String [] tabCorrect= {" "," "," "," "};
 
 
			public static void main(String[] args) {
 
						String [] combinaisonSecrete = generateRandomCombination();
						for(int i=0;i<4;i++) {
							System.out.print(combinaisonSecrete[i]+ "|");
						}
						String [] combinaisonJoueur;
						System.out.println();
						do {
							combinaisonJoueur = choixNumerote();
							for(int i=0;i<4;i++) {
								System.out.print(combinaisonJoueur[i]+ "|");
							}
							//??
						}while (compteur<=12 && (12-compteur)>0);
 
						compareColor (tabJoueur, combination);
					    for(int k=0;k<4;k++) {
							System.out.print(tabCorrect[k]+ "|");
						}
 
						sc.close();
				}
 
    // Generate random combination of 4 colors 
    static String [] generateRandomCombination() {
        String [] combination = new String[NB_COLORS];
        int currentPosition = 0;
        while(currentPosition!=NB_COLORS) {
            int indexRandom = (int)(Math.random()*TAB_REF_COLORS.length);
            String color = TAB_REF_COLORS[indexRandom];
            if(!isIn(color, combination)) {
                combination[currentPosition] = color;
                currentPosition++;
            }
        }
        return combination;
    }
 
    static boolean isIn(String iStringToFind, String [] iTab) {
        int size = iTab.length;
        for(int i=0;i<size;i++) {
            if(iStringToFind.equalsIgnoreCase(iTab[i])) return true;
        }
        return false;
    }
// fonction pour récupérer le tableau de l'utilisateur
    static String [] choixNumerote() {
        String [] tabJoueur = new String[NB_COLORS];
        for(int i=0;i<NB_COLORS;i++) {
            System.out.println();
            System.out.println("Choisissez une couleur :");
            tabJoueur[i]=sc.nextLine();
        }
        compteur++;
		System.out.println("Il te reste : " + (12-compteur) + " tentative(s)");
		if (compteur==12) {
			System.out.println("La partie est finie. Tu as perdu !");
 
		}
		return tabJoueur;
 
    }
 
// fonction pour faire la comparaison entre les 2 tableaux et stocker les élément en communs
    static void compareColor (String [] tabPlayer, String [] tabOrdi) {
        int sizeTj = tabPlayer.length;
        int sizeTm = tabOrdi.length;
        int k=0;						
                for (int i=0;i<sizeTj;i++) {
                    for(int j=0; j<sizeTm; j++) {
                        if (tabOrdi[j]==tabPlayer[i]) {
                        System.out.print("Vous avez trouver une couleur");
                        tabCorrect[k]=tabOrdi[j];
                        k++;
                    }
                        else {
                        	continue;
                        }
                    }
            }
 
        }
}

I make this for the statement :

        int sizeTj = 0;
        sizeTj = tabPlayer.length;
 
        int sizeTm = 0;
        sizeTm = tabOrdi.length;
 
        int k=0;

but the problem remains. For me there are 2 variables is this statement and both of them are declared and initialisized. I really don't know.

I think I see where the problem is. Just a minute please. Thank you very much

--- Update ---

No .. big deception. I've written this :

static String [] tabPlayer = new String[NB_COLORS];
static String [] tabOrdi = new String[NB_COLORS];

.
But doesn't work. I've even been skeptical about initializing funnction's argument

"defines a String array but does not assign any values to the array's elements. " but I am defining the function. In the main, there will be the values of the array's elements, that are given by the previous return tabJoueur; and return combination; .... isn't right ?
I removed the word static and renamed the variables as suggested by Eclipse.

static void compareColor (String [] tabPlayer, String [] tabOrdi) {
    	String [] tabPlayer1 = new String[NB_COLORS];
    	String [] tabOrdi1 = new String[NB_COLORS];

And it seems working ... at least I didn't have the NullPOinterException message anymore.

Thank you Norm