Question: So here is the code, and there are few lines I don't understand. 

```
account acct = new account(); // making a new object named acct, type:account

ConsoleAccountEvents c1 = new ConsoleAccountEvents(acct); // new object created with parameters.

acct.addObserver(c1); // also not sure. 

acct.addTransaction(100.00); // not sure.... 

```

This is Java. I'm not sure how parameters are passed to the constructor.

Answer: 
In java, the constructor is invoked when the object of the class is created using the `new` keyword. So to call the constructor with a certain parameter you just have to create an object with parameter as per your requirement example in your case.

```
class ConsoleAccountEvents {

    Account account;

    public ConsoleAccountEvents(Account account) {
        this.account = account;
    }
}

class Account {

}

```

So when you create object with 

```
Account acct = new Account(); 
ConsoleAccountEvents c1 = new ConsoleAccountEvents(acct);

```

So here parameterized constructor will be called and this object will be assigned in instance variable of `ConsoleAccountEvents` class
Your `ConsoleAccountEvents` class must look like something like this-

```
class ConsoleAccountEvents {
    Account accObject; // you have an object of 'Account' class as a member variable in this class
    // other variables
    public ConsoleAccountEvents() {
        // body here
    }
    public ConsoleAccountEvents(Account accObject) {
        this.accObject = accObject; // see below
        // body here
    }
    // others
}

```

Doing this `ConsoleAccountEvents c1 = new ConsoleAccountEvents(acct);`

You are calling the parametrized constructor which takes an `Account` object as parameter and generally initialize the `accObject` (object of `Account` class) in `ConsoleAccountEvents` with it. 

Now, For `acct.addObserver(c1);`

In your `Account` class you must have a method `addObserver` that takes a `ConsoleAccountEvents` as parameter. like

```
void addObserver(ConsoleAccountEvents evOb) {
    // body
}

```

***PS:*** Please follow java naming conventions and other conventions, like capitalizing the first letter of name of a class etc.

And stackoverflow is not going to be of much help if you dont go through [Java Language Tutorial](http://docs.oracle.com/javase/tutorial/java/index.html). Good luck...!