java how to program exercise 3.12

java how to program exercise 3.12
public class AccountTest {

public static void main(String[] args) {

Account account1 = new Account(50.00);
Account account2 = new Account(-7.53);

double depositAmount;
double debitamount;








}

}//end class

class Account {

private double balance;

public Account(double initialBalance) {
if (initialBalance (user greater sign here) 0.0) {
balance = initialBalance;
}
}

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

public void debit(double amount)
{
if(amount(user less than sign here)balance)
{
balance = balance-amount;
}
else
{
}
}

public double getBalance() {
return balance;
}

}