NullPointerException.. Where is the flaw in my logic?

In Main:

Equipe Eq1 = new Equipe(J,E);
Equipe Eq2 = new Equipe(J,E);
while(Eq1.equals(Eq2))
Eq2 = new Equipe(J,E);

Match m = new Match(Eq1,Eq2);
String ChercherJoueur = m.QuelEquipe(m.hasBall());

In Class Equipe:

public Vector<Joueur> VJ;
public Equipe(Vector<Joueur> E, Vector<Entraineur> Ent) {
   VJ = new Vector<Joueur>();
   //rest of the logic
}
public Equipe() {
}

In Class Match:

Equipe Eq1 = new Equipe();
Equipe Eq2 = new Equipe();
public Match(Equipe Eq1, Equipe Eq2) {
Eq1 = this.Eq1;
Eq2 = this.Eq2;
}

public String QuelEquipe(Joueur J)
{
    boolean found = Eq1.ChercherJoueur(J);
    if(found == true)
        return "EQ1";
    else
        return "EQ2";
}

public Joueur hasBall()
{
    Joueur J = null;
    int i = 0;
    boolean found = false;

NullPointerException------->  System.out.println(Eq1.VJ.get(i).isBall());

System.out.println(Eq2.VJ.get(i).isBall());
    while(!found)
    {

        if((Eq1.VJ.get(i).isBall())==true)
        {
            found = true;
            J= Eq1.VJ.get(i);
        }

        else if((Eq2.VJ.get(i).isBall())==true)
        {
            found =开发者_运维百科 true;
            J= Eq2.VJ.get(i);
        }
        i++;
    }
return J;
}
}

I think is all I need to include here to inform u about the situation.. I get a NullPointerException when I do "m.QuelEquipe(m.hasBall());" that can be traced back to where I pointed in The Class Match.. I know exactly what the exception means, and I'm changing their references with "Eq1 = this.Eq1;Eq2 = this.Eq2;" anyway.. sooo where is flow to get the code to work??

Your constructor using two args does initialize the vector but the parameterless constructor doesn't

public Equipe(Vector<Joueur> E, Vector<Entraineur> Ent) {
    VJ = new Vector<Joueur>(); //<-- OK
    //rest of the logic
}
public Equipe() {
        //<-- errrk
}

Then when you invoke:

System.out.println(Eq2.VJ.get(i).isBall());

You're using really invoking:

Eq2.null.get  <-- NullPointerException 

But the real problem though is in the Match constructor:

public Match(Equipe Eq1, Equipe Eq2) {
    Eq1 = this.Eq1;
    Eq2 = this.Eq2;
}

Here you're assigning to the local variable Eq1 the value of the instance variable Eq1 you really want it the other way around:

public Match(Equipe Eq1, Equipe Eq2) {
    this.Eq1 = Eq1;
    this.Eq2 = Eq2;
}

BTW, this is not C# and in Java as a coding conventions both, methods and attributes start with lowecase and opening brace goes in the same line ( although this last part is not as relevant as the naming convention )

I hope this helps.

You are calling the default constructor public Equipe() which does not initialize VJ. Just remove the constructor if you are not going to use it.

This will fix your problem:

Match.java

private final Equipe eq1;
private final Equipe eq2;
public Match(final Equipe eq1, final Equipe eq2) 
{
   this.eq1 = eq1;
   this.eq2 = eq2;
}