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POLast.fm java.lang.ClassCastException - reading in User objects from file
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2013-12-03T17:50:40.483
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2013-12-03T18:04:20.437
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I would really appreciate if anyone can help me with this issue. I'm getting an error when I run this class UniqueUsersData.java <pre><code>Exception in thread "main" java.lang.ClassCastException: java.lang.String cannot be cast to java.util.HashSet at gettingData.UniqueUsersData.main(UniqueUsersData.java:30) </code></pre> UniqueUsersData.java: <pre><code>package gettingData; import java.io.BufferedInputStream; import java.io.BufferedWriter; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.FileWriter; import java.io.IOException; import java.io.InputStream; import java.io.ObjectInput; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import java.util.ArrayList; import java.util.HashSet; import java.io.Serializable; import de.umass.lastfm.User; public class UniqueUsersData { public static void main(String[] args) throws IOException, ClassNotFoundException{ HashSet<User> userData = null; String fileName = "users.csv"; ObjectInputStream in = new ObjectInputStream(new FileInputStream(fileName)); try{ while(in != null ){ // keep reading if there are more lines in the file userData = (HashSet<User>) in.readObject(); } }catch(IOException e){ e.printStackTrace(); } String file = "usersInfo.csv"; BufferedWriter out = new BufferedWriter(new FileWriter(file, true)); for(User u: userData){ System.out.println(u.getId() + "," + u.getName() + "\n"); } out.close(); } // end main method } // end class </code></pre> I have another class which gets the data using the last.fm api, stores User objects to an arraylist and then writes those objects to a file (users.csv). That all works fine, and I write to the file using an <code>ObjectOutputStream</code>. I've read things about the class needing to be <code>Serializable</code>, but I'm assuming that <code>de.umass.lastfm.User</code> doesn't implement it. Is there something I'm missing here? Thanks for any help! 
Tags
<java><serializable><objectinputstream><last.fm>
Title
Last.fm java.lang.ClassCastException - reading in User objects from file
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