[Solved] How do I return/implement the toString for the ArrayList? Also, just want to check that I’ve correctly created my objects?

You have a lot of error in your code :

First
Don’t ever name your variables with Upper letter in beginning, java use camelCase

Second
Don’t declare your variable with private public in your method.

private ArrayList<Object> List = new ArrayList<Object>();

Third
You can’t declare a method inside another method you have to close the first when you finish:

public static void main(String args[]){//------Start
  ...
}//---End

public String toString(){//---Start
  ...
}//---End

Forth
When you want to call a method with paramettres you can pass them like this :

method(list);

Fifth
ArrayList already impliment toString so you don’t need to create it again, you can use :

list.toString()

If you want to implement it again you can use :

public static void main(String[] args) {
    King newLoan = new King();
    Date theDate = new java.util.Date();
    Circle newCircle = new Circle();
    String s = new String();

    ArrayList<Object> list = new ArrayList<Object>();

    list.add(newLoan);

    list.add(theDate);

    list.add(newCircle);

    list.add(s);

    System.out.println(newLoan.toString(list));
}

public String toString(ArrayList<Object> list) {
    String results = "";
    for (Object d : list) {
        results += "," + d.toString();
    }
    return results;
}