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POJava Serialization Conundrum
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copied!<p>I am having some problem with Serialization</p> <p>Here goes my code for writing mClassifier object to a file:</p> <pre><code>FileOutputStream fileOut = new FileOutputStream("C:\\polarity.model"); ObjectOutputStream objOut = new ObjectOutputStream(fileOut); mClassifier.compileTo(objOut); objOut.close(); </code></pre> <p>It works fine and writes stuff to the file.</p> <p>But there is a catch: <code>myClassifier</code> object is of type <code>DynamicLMClassifier</code>. <code>compileTo</code> method above however returns an instance of LMClassifier (superclass)</p> <p>Here goes my code for reading the object:</p> <pre><code>FileInputStream in = new FileInputStream("C:\\polarity.model"); ObjectInputStream ois = new ObjectInputStream(in); mClassifier = (DynamicLMClassifier)(ois.readObject()); ois.close(); </code></pre> <p>When I read the object I typecast it to <code>DynamicLMClassifier</code> and it too works fine but I dont get the output I desired. While reading the object again should it not be typecasted to <code>LMClassifier</code> rather than <code>DynamicLMClassifier</code>. However if I do that, compiler complains that it should be of type <code>DynamicLMClassifier</code>.</p> <p>Can the above be problems or am I doing something wrong some where else. I mean the code without serialization is working perfectly fine and I get the desired output, I mean when the object is in memory.</p> <p>EDIT: Here is the complete code (just remove the serialization part in the <code>train()</code> and <code>getSentiments()</code> method and it works as intended), Also note that in (1) With Serialization I am not calling <code>getSentiments()</code> and I am just training i.e. calling the train () method (2) Now i have a serialized model after (1) and I am not calling the <code>train()</code> method just calling <code>getSentiment()</code> by just commenting out appropriate code in main:</p> <pre><code>public class PolarityBasic{ File mPolarityDir; String[] mCategories; DynamicLMClassifier<NGramProcessLM> mClassifier,readClassifier; PolarityBasic(String[] args) { System.out.println("\nBASIC POLARITY DEMO"); mPolarityDir = new File("C:\\review_polarity","txt_sentoken"); System.out.println("\nData Directory=" + mPolarityDir); mCategories = mPolarityDir.list(); int nGram = 8; mClassifier = DynamicLMClassifier .createNGramProcess(mCategories,nGram); } void run() throws ClassNotFoundException, IOException { train(); } boolean isTrainingFile(File file) { return file.getName().charAt(2) != '9'; // test on fold 9 } void train() throws IOException { int numTrainingCases = 0; int numTrainingChars = 0; System.out.println("\nTraining."); for (int i = 0; i < mCategories.length; ++i) { String category = mCategories[i]; Classification classification = new Classification(category); File file = new File(mPolarityDir,mCategories[i]); File[] trainFiles = file.listFiles(); for (int j = 0; j < trainFiles.length; ++j) { File trainFile = trainFiles[j]; if (isTrainingFile(trainFile)) { ++numTrainingCases; String review = Files.readFromFile(trainFile,"ISO-8859-1"); numTrainingChars += review.length(); Classified<CharSequence> classified = new Classified<CharSequence>(review,classification); mClassifier.handle(classified); } } } FileOutputStream fileOut = new FileOutputStream("C:\\review_polarity/polarity.model"); ObjectOutputStream objOut = new ObjectOutputStream(fileOut); mClassifier.compileTo(objOut); objOut.close(); System.out.println(" # Training Cases=" + numTrainingCases); System.out.println(" # Training Chars=" + numTrainingChars); } String getSentiment(String text) { try{ FileInputStream in = new FileInputStream("C:\\review_polarity/polarity.model"); ObjectInputStream ois = new ObjectInputStream(in); mClassifier = (DynamicLMClassifier)(ois.readObject()); ois.close(); } catch(Exception e){} Classification classification = null; classification = readClassifier.classify(text); System.out.println("classification: " + classification); return (classification.bestCategory()); } public static void main(String[] args) { try { PolarityBasic pB = new PolarityBasic(args); pB.run(); String text = null; text = "It was awesome !"; System.out.println("The text \"" + text + "\" is " + pB.getSentiment(text)); } catch (Throwable t) { System.out.println("Thrown: " + t); t.printStackTrace(System.out); } } } </code></pre>

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