Exception error in "main" thread java.lang.NillPointerException in BAnco.java:36

Hello! Please someone can help me, I am learning now to program, and I am with that difficulty

In the case that it is not in the operating system,
I already referred the project to everything, all the classes, I have seen the videos innumerable times, but I am not knowing how to identify the error.

Can you help me please?

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public class ContaJ implements Cuenta {

private double balance = 0.0;

// Interest rate applied
public static final double I = 0.05;

public void extracto () {noun.
System.out.println ("Balance of account F" + balance);

}

public void deposit (double value) {
balance = balance + value;
System.out.println ("value deposited:" + value);
}

public void serve (double value) {
if (value <= balance) {
balance = balance – value;
System.out.println ("Return value:" + value);
}
} else {
System.out.println ("Insufficient balance");
}
}

public double simulaEmprestimo (double cf, int n) {}
return I / (1-1 / Math.pow (1 + I, n)) * cf;
}
}

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public class ContaF implements Cuenta {

private double balance = 0.0;

// Interest rate applied
public static final double I = 0.03;

public void extracto () {noun.
System.out.println ("Slate of account F" + balance);

}

public void deposit (double value) {
balance = balance + value;
System.out.println ("value deposited:" + value);
}

public void serve (double value) {
if (value <= balance) {
balance = balance – value;
System.out.println ("Return value:" + value);
}
} else {
System.out.println ("Insufficient balance");
}
}

public double simulaEmprestimo (double cf, int n) {}
return I / (1-1 / Math.pow (1 + I, n)) * cf;
}
}

==========================================================================================
(in English).

public void extract ();
public void deposit (double value);
public void serve (double value);

// = funded capital, n = months
public double simulaEmprestimo (double cf, int n);

}

==============================================================================
import java.util.ArrayList;

public class BAnco {

public static void main (String args[]) {}

ArrayList list_of_Clients = new ArrayList ();

Correntista c1 = new Correntista ("Matheus", new AccountF ());
list_of_Clients.add (c1);
Correntista c2 = new Correntista ("Arlindo", new AccountF ());
list_of_Clients.add (c2);
Correntista c3 = new Correntista ("Josefanilda", new AccountF ());
Customer_list.add (c3);
Correntista c4 = new Correntista ("Jucintolucio", new AccountF ());
list_of_Clients.add (C4);

(In the case of a person).
list_of_Clients.add (cJuridic);

c1.exibe_Indentfiacao ();
c2.exibe_Indentfiacao ();
c3.exibe_Indentfiacao ();
c4.exibe_Indentfiacao ();
cJuridico.exibe_Indentfiacao ();

double valueParcela = c1.getConta (). simulaEmprestimo (1000.0, 12);
System.out.println (valueParcela); // Giving error

}
}