Question

hello everyone I am newto programming and I am just a little bit confused. I have three files in java

Product.java this file defines the product attributes like product name, quantity, ID
in this file i dont have a main

ProductCollection.java
this file create a vector to hold data temporarily when accessing database

Database.java
database connection

EServer
communicate with client and retrieve access database

rs = query.executeQuery(queryString);
pColl = new ProductCollection();<-------------------confuse
product extractedProduct; <------------------------ confuse
while(rs.next())
{

    extractedProduct = (Product).addProduct(rs);
    // Object [ ] extractedProduct  = ProductCollection.addProduct(rs);
}

EClient.java

can someone explain this two line please

[ pColl = new ProductCollection();] [ product extractedProduct;]

also I am struggling to add an object to store the result temporary. Can someone help me please I want extract out the contents of a row and set up a Product object extractedProduct

Answer 1

pColl = new ProductCollection();

This is as simple assignment. On the left hand side you have a variable, pColl, and on the right hand side you have an expression that creates a new object of type ProductCollection and returns a reference to it.

product extractedProduct;

This is a variable declaration which says, “from this line on, I want to be able to use a variable which I call extractedProduct and it refers to a product” (or, put another way, you declare a variable of type product).

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The Java convention says that class names should start with a capital letter, so you probably want to change the name of the class so it reads

Product extractedProduct;

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Useful links:

• Official trail on Java Variables