Describe the different types of numeric variables in Java.
There are two main types of numeric variables: integers, which are whole numbers, and floating point variables, which contain decimals. The four types or integers are a byte, short, int, and long. The difference between each of these is how much size is used on the computer when they are stored. A byte uses one byte, a short uses 2 bytes, an int uses 4 bytes and a long uses 8 bytes. It is common to use 'int' unless it is possible for the variable to become very large, requiring more space than the 4 bytes used in an int. If the variable needs to contain decimals, you can use a float or a double. Again, these differ by size. A float is stored in bytes and a double is stored in 8 bytes.
What is the difference between a Doubly Linked List and a Singly Linked List?
First of all, a Linked List is a data structure containing items as independent nodes linked to each other. Each node contains its own information and points to the next node. Each node can only point to one node. Imagine this list: A, B, C. In a Linked List it would look like this: A -> B -> C As you can see, A points to B. This means that if you are running through the linked list when you get to A you can only see that B is next, you have no information on C. This example is a singly linked list because each node is only linked to the node that follows. In a doubly linked list, each node has a reference to the node after it as well as the node before it. A doubly linked list looks like this: A <--> B <--> C If you are currently at node B, you can move to node A or node C because B is linked to both of them. In short, a singly linked list contains nodes that are only linked to the node that follows them and nodes in a doubly linked list contains links to the nodes before and after them.
What is the best way to approach an ACT problem?
It depends on the subject. There are four subjects with multiple choice answers: English, Math, Reading, and Science. I find some general methods work well in each test, such as making a running list as you go of questions that haven't been answered and a separate list of questions you want to double check and returning to them after you complete everything else. I also find it helpful to look at the number of questions in the section as well as the total allotted time and calculate the average time per question, that way you can see if you're ahead or behind schedule as you move through. However, many subjects have specific tactics that deserve their own explanation. For example, if you are stuck on a Math problem it may save time and frustration to plug in each answer into the question and see if one works.