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POjava. Method return Null. What exception I must generated?
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  1. POjava. Method return Null. What exception I must generated?
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    copied!<p>I have this line code:</p> <pre><code>String name = Book.getName(); /*next lines of code*/ </code></pre> <p>Next, variable <code>name</code> processing in other code without any checks. In some cases, possible situation, when <code>name=null</code> and other code will exit with an error.</p> <p>It is bad. </p> <p>Also, I cant access to the other code.</p> <p><strong>So, what do you think, my next implementation is correct</strong>:</p> <pre><code> try { String name = Book.getName(); if(null== name) throw new NullPointerException("method 'getName' return null"); /*next lines of code*/ } catch(NullPointerException e) { System.out.print("Hey! Where book name? I exit!"); System.exit(); } </code></pre> <p><strong>I have any other choose in this case?</strong></p> <p>It is possible to generate any other type of <code>Exception</code> or only <code>NullPointerException</code>?</p> <p>Thanks.</p> <p><strong>Edit:</strong></p> <p>Ok, </p> <pre><code> String name = Book.getName(); </code></pre> <p>it's imagine code line. In real case, I have more complex code:</p> <pre><code>List&lt;Book&gt; bookList= new ArrayList&lt;Book&gt;(); String name = null; Iterator i = BookShop.getBooks.iterator(); //BookShop it is input parameter! while(i.hasNext()) { Book book = (Book) i.next; name = book.getName(); nameList.add(name); } </code></pre> <p>This example more full.</p> <p>So, in this code input parameter <code>BookShop</code> Object.</p> <p>What problem I can have with this Object?</p> <ol> <li>BookShop can be <code>NULL</code>;</li> <li>method <code>BookShop.getBooks()</code> can return <code>NULL</code>;</li> </ol> <p>Also, <code>getName()</code> can return <code>NULL</code> too.</p> <p>So, general problem next: <strong>there is no guarantee the correctness of input parameter BookShop!</strong></p> <p>And I must to consider every possible option (3 <code>NULL</code>)</p> <p>For me, add General <code>try-catch</code> block and that all.</p> <p>No?</p>
 

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