NEED SOME GUIDANCE FOR JAVA DATA STRUCTURES

First off, I conquer one thing at a time, as inheritance and serialization are really separate concepts.

1. Inheritance: The general idea of inheritance is that one class inherit properties from another class. One example I like to use for this is Animals. Say we created a base Animal class:

public class Animal {
    public String name;
    public double weight;
    public int numberOfLegs;

    public Animal(String name, double weight, int numLegs) {
        this.name = name;
        this.weight = weight;
        this.numberOfLegs = numLegs;
    }

    ... other methods for the class...

}

This class suggests that all animals should have a name, weight and count for the number of legs.

Now we could create a subclass of an Animal, say a Cow:

public class Cow extends Animal {
    public boolean spotted;
    public boolean dairyCow;
    ...

    public Cow(String name, double weight, boolean spotted, boolean dairyCow) {
        this.name = name;
        this.weight = weight;
        this.numberOfLegs = 4; // will assume all cows have 4 legs.
        this.spotted = spotted;
        this.dairyCow = dairyCow;
    }

    ... More methods specific to cows...

    ... Can also override methods within Animal....

}

This subclass allows Cows to inherit the base properties of what an Animal should be described as (name, weight, number of Legs) as well as adding in descriptors that are specific to Cows (spots, dairyCow, etc.).

Note that in Java, multiple inheritance is not allowed. So a cow can only extend Animal, not something like extend Animal, Mammal, etc...

Hopefully, this helps with the idea of inheritance. Post more questions as you have them.

1. Serialization is a way of packaging up an Object (into a byte array/stream). Now for the why... why do we want to serialize? This can be used to save objects to disk, for persistence, for caching, for communication, etc. This one I don't have as good of a quick example for, but here are a few good links that will hopefully help a bit:

http://www.tutorialspoint.com/java/java_serialization.htm

http://stackoverflow.com/questions/447898/what-is-object-serialization

http://stackoverflow.com/questions/2232759/what-is-the-purpose-of-serialization-in-java