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I'm trying to read objects from a file in the Internet. I have been given the object class, which is this:

import java.io.Serializable; public class Sulearvuti extends Arvuti implements Serializable { private static final long serialVersionUID = 1L; //isendiväli private int aku; //konstruktor public Sulearvuti(String tootja, String mudel, String lisainfo, int järjekorraNumber, int raskusaste, boolean kiirtellimus, int aku) throws ValeRaskusAsteErind { super(tootja, mudel, lisainfo, järjekorraNumber, raskusaste, kiirtellimus); this.aku = aku; } // meetod toString, kasutama ülemklassi meetodit public String toString() { return "Sülearvuti [aku=" + aku + ", " + super.toString() + "]"; } // meetodi ülekatmine double parandamiseAeg(){ return this.getRaskusaste()*2; } }

Now when I'm trying to read the objects (Sulearvuti), I get ClassNotFoundException. This is the piece of code :

ObjectInputStream ois = new ObjectInputStream ( new URL("http://www.ut.ee/~marinai/sulearvutid.dat") .openConnection() .getInputStream()); int arv=ois.readInt(); Sulearvuti sülearvuti=(Sulearvuti)ois.readObject();

There's no problem with the Integer, but it won't recognize the class. I've been desperate for the past hour or so...

Also here's the code for the superclass "Arvuti":

import java.io.Serializable; public class Arvuti implements Serializable, Comparable<Arvuti> { private String tootja; private String mudel; private String lisainfo; private int jrnumber; private int vea_raskusaste; private boolean kiirtellimus; String getTootja() { return tootja; } String getMudel() { return mudel; } String getLisainfo() { return lisainfo; } int getJrnumber() { return jrnumber; } int getVea_raskusaste() { return vea_raskusaste; } boolean isKiirtellimus() { return kiirtellimus; } void setTootja(String tootja) { this.tootja = tootja; } void setMudel(String mudel) { this.mudel = mudel; } void setLisainfo(String lisainfo)throws WindowsXPErind { this.lisainfo = lisainfo; if(lisainfo.contains("WindowsXP"))throw new WindowsXPErind(); } void setJrnumber(int jrnumber) { this.jrnumber = jrnumber; } void setVea_raskusaste(int vea_raskusaste)throws ValeRaskusAsteErind { if(vea_raskusaste<1 || vea_raskusaste>10) throw new ValeRaskusAsteErind(); this.vea_raskusaste = vea_raskusaste; } void setKiirtellimus(boolean kiirtellimus) { this.kiirtellimus = kiirtellimus; } Arvuti(String tootja, String mudel, String lisainfo, int jrnumber, int vea_raskusaste, boolean kiirtellimus)throws ValeRaskusAsteErind { try{ setTootja( tootja); setMudel(mudel); setJrnumber(jrnumber); setVea_raskusaste(vea_raskusaste); setKiirtellimus(kiirtellimus); setLisainfo(lisainfo); } catch (WindowsXPErind e){ System.out.println("WindowsXPErind"); setVea_raskusaste(vea_raskusaste+2); } } double parandamiseAeg(){ return getVea_raskusaste()*1.5; } public String toString() { return "Arvuti [tootja=" + tootja + ", mudel=" + mudel + ", lisainfo=" + lisainfo + ", järjekorranumber=" + jrnumber + ", vea raskusaste=" + vea_raskusaste + ", kiirtellimus=" + kiirtellimus + ", parandamise aeg=" + parandamiseAeg() + "]"; } public int compareTo(Arvuti arvuti){ if(this.isKiirtellimus()==true && arvuti.isKiirtellimus()==false) return -1; else if(this.isKiirtellimus()==false && arvuti.isKiirtellimus()==true) return 1; else{ if(this.getJrnumber()<arvuti.getJrnumber())return -1; else if(this.getJrnumber()>arvuti.getJrnumber())return 1; else return 0; } } }

Exception in thread "main" java.lang.Error: Unresolved compilation problem:

Unhandled exception type ClassNotFoundException at Peaklass.main(Peaklass.java:36)
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  • why are you using ObjectInputStream to read HTTP based URLs. You should be using as a bare minimum, HttpURLConnection instead. Commented May 5, 2014 at 17:38
  • because the file was written with ObjectOutputStream Commented May 5, 2014 at 17:46
  • I could read in your file, at least as much as I could derive from the information you have given, aku=5, tootja=Ordi, mudel=Enduro i576CSH Power, lisainfo=, järjekorraNumber=2, raskusaste=5, kiirtellimus=false. Without knowing more about your Arvuti class there’s no chance of finding the problem. Commented May 5, 2014 at 17:51
  • Your Arvuti class is missing the private static final long serialVersionUID = 1L;. But that would provoke a java.io.InvalidClassException rather than a ClassNotFoundException. That’s the only issue I see. Can you post the exact exception stack trace? Commented May 5, 2014 at 18:03
  • Exception in thread "main" java.lang.Error: Unresolved compilation problem: Unhandled exception type ClassNotFoundException at Peaklass.main(Peaklass.java:36) (that's the readObject() line) Commented May 5, 2014 at 18:07

2 Answers 2

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You are missing some classes contained in the .dat file. Lookout for the classname shown in the classnotfound exception.

It is not sufficient to have the "Sulearvuti", you also need "Arvuti" (superclass) and "ValeRaskusAsteErind" (Exception) in your classpath.

BTW the language looks very funny to me, what language is this ?

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1 Comment

It's Estonian. I have the superclass and different Exceptions. I'll add the code of the superclass.
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Is "Sulearvuti" class on the classpath of the application trying to deserialize the object?

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