I realize that this program is for beginners. In any case, I can't find
the problem. Here it is:
(It's supposed to print out alice: balance = 625; bob = 436; I don't
think it's adding the interest and I can't see why)

public class BankDemo {
 public static void main(String[]  args)  {
   BankAccount alice = new BankAccount(0);
   BankAccount bob = new BankAccount(0);
   alice.deposit(500);
   bob.deposit(500);

   System.out.println("Alice's balance: " + alice.getBalance());
   System.out.println("Bob's balance: " + bob.getBalance());

   alice.addInterest(5);
   alice.transferFunds(bob, 100);
   bob.addInterest(6);
   bob.transferFunds(alice, 200);

   System.out.println("Alice's balance: " + alice.getBalance());
   System.out.println("Bob's balance: " + bob.getBalance());

   System.out.println("Alice:\t" + alice);
   System.out.println("Bob:\t" + bob);

 }
}
class BankAccount  {
 public BankAccount(double initialBalance)  {
   double balance = initialBalance;
  }

 public void deposit(double amount)  {
   balance = balance + amount;
 }

 public void withdraw()  {
    balance = balance - 100;
 }

 public void withdraw(double amount)  {
   balance = balance - amount;
 }

 public double getBalance()  {
   return balance;
 }

 public String toString()  {
   return "BankAccount [balance=" + balance + "]";
 }

 private double balance = 0;

 public void addInterest(double interestRate) {
    double Interest = interestRate / 100;
 }

 public void setBalance(double amount)  {
   withdraw(getBalance());
   deposit(amount);
 }

 public void transferFunds(BankAccount name, double amount)  {
   withdraw(amount);
   name.deposit(amount);
 }

 }

// add 5% interest to alice's account balance
//alice.addInterest(5);

// move $100 from alice's account into bob's
// alice.transferFunds(bob, 100);

// add 6% interest to bob's account balance
//bob.addInterest(6);

// move $200 from bob's account into alice's
//bob.transferFunds(alice, 200);

//System.out.println("Alice:\t" + alice);
//System.out.println("Bob:\t" + bob);