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POJava: checked vs unchecked exception explanation
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  1. POJava: checked vs unchecked exception explanation
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    copied!<p>I have read multiple posts on StackOverFlow about checked vs unchecked exceptions. I'm honestly still not quite sure how to use them properly. </p> <p>Joshua Bloch in "<em>Effective Java</em>" said that </p> <blockquote> <p>Use checked exceptions for recoverable conditions and runtime exceptions for programming errors (Item 58 in 2nd edition)</p> </blockquote> <p>Let's see if I understand this correctly.</p> <p>Here is my understanding of a checked exception:</p> <pre><code>try{ String userInput = //read in user input Long id = Long.parseLong(userInput); }catch(NumberFormatException e){ id = 0; //recover the situation by setting the id to 0 } </code></pre> <p><strong>1. Is the above consider a checked exception?</strong></p> <p><strong>2. Is RuntimeException an unchecked exception?</strong></p> <p>Here is my understanding of an unchecked exception:</p> <pre><code>try{ File file = new File("my/file/path"); FileInputStream fis = new FileInputStream(file); }catch(FileNotFoundException e){ //3. What should I do here? //Should I "throw new FileNotFoundException("File not found");"? //Should I log? //Or should I System.exit(0);? } </code></pre> <p><strong>4. Now, couldnt the above code also be a checked exception? I can try to recover the situation like this? Can I?</strong> (Note: my 3rd question is inside the <code>catch</code> above)</p> <pre><code>try{ String filePath = //read in from user input file path File file = new File(filePath); FileInputStream fis = new FileInputStream(file); }catch(FileNotFoundException e){ //Kindly prompt the user an error message //Somehow ask the user to re-enter the file path. } </code></pre> <p><strong>5. Why do people do this?</strong></p> <pre><code>public void someMethod throws Exception{ } </code></pre> <p>Why do they let the exception bubble up? Isn't handling the error sooner better? Why bubble up? </p> <p><strong>EDIT: Should I bubble up the exact exception or mask it using Exception?</strong></p> <p><strong>Below are my readings</strong></p> <p><a href="https://stackoverflow.com/questions/499437/in-java-when-should-i-create-a-checked-exception-and-when-should-it-be-a-runtim">In Java, when should I create a checked exception, and when should it be a runtime exception?</a></p> <p><a href="https://stackoverflow.com/questions/27578/when-to-choose-checked-and-unchecked-exceptions">When to choose checked and unchecked exceptions</a></p>
 

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