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    <blockquote> <p>private Stock [] stocks, does it mean that the stock inventory program will store the info into an array? If it is, how do I store all the details associated with a particular stock, company name, price, etcs together.</p> </blockquote> <p>Your array is like a <code>list</code> of stocks. But just because its one object, doesn't mean it only contains one piece of data. It can hold Strings, ints, and other user-defined data types. Therefore, you can store pieces of data relating to the stock inside the <code>Stock</code> object.</p> <pre><code>public class Stock { private String companyName; private String stockRating; private int price; private int numberOfShares; </code></pre> <p>Those are all stored in each Stock object, and can be accessed by the <em>getter</em> methods you defined.</p> <p><code>int stockdata = stocks[4].getPrice();</code></p> <p>However, to initialize your <code>Stock</code> array, you want to create a new <code>Stock</code> object for each area, like so:</p> <pre><code>for(int i = 0; i &lt; INVENTORY_SIZE; i++) { stocks[i] = new Stock(foo, bar, lorem, ipsum); } </code></pre> <p>The variables used here are just placeholders, so you can create your parameters by reading from the console like you're doing above.</p> <p><a href="http://codebetter.com/raymondlewallen/2005/07/19/4-major-principles-of-object-oriented-programming/" rel="nofollow">These design principles for OOP should help you understand the relationship between <em>data</em> and <em>containers</em>.</a></p> <p>For the second part of your question, you can look at just comparing one of the data values, like <code>companyName</code>, or <a href="http://docs.oracle.com/javase/tutorial/java/concepts/interface.html" rel="nofollow">implementing an interface</a> like <a href="http://docs.oracle.com/javase/1.4.2/docs/api/java/lang/Comparable.html" rel="nofollow">Comparable</a>.</p> <pre><code>for(Stock s : stocks) { if(stockName.equals(s.getCompanyName()) { // ERROR! } } </code></pre>
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    1. USDavid B
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    1. COHey David, do you have time to take a look at my updated code? The code will runs but after the user inputs the last detail, numberOfshares, the program crashes and outputs an nullPointerException error. I am not sure what went wrong.
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    2. COI think the nullPointerException is because you never create a new StockInventory, so stocks[] never gets initialized. Frank;\ly, I don't see how your code compiles, the static method shouldn't be able to refer to the field stocks. Try not to mixup static methods with fields of an object.
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