CODEWITHSUNDEEP
javatreemap
sys_debug
sys_debug

Reputation: 4003

Java Serializing Map to file

I wrote this function which will attempt to store the map but its not working I think? I am using netbeans and each time i go to the directory of project in the java src i can't find the created file or anywhere else in the project. The map is surely valid because output comes out perfect when am not dealing with storage. btw I do implement seriliazable :)

Note: the map is of type TreeMap

 public boolean storeMap(TreeMap<DateTime, Integer> map){
   try{
     f_out = new FileOutputStream("mapObject.data");
     obj_out = new ObjectOutputStream (f_out);
     obj_out.writeObject(map);
     return true;
    }catch(IOException ioe){
        System.err.print(ioe);
        return false;
    }
}

is there a reason why the output file is not generated? Thanks

Upvotes: 1

Views: 5468

Answers (3)

Kumar Gaurav
Kumar Gaurav

Reputation: 107

SERIALIZE A HASHMAP: This code is working fine , I have implemented and used in my app. Plz make ur functions accordingly for saving map and retrieving map.

Imp thing is, you need to make confirm that the objects you are putting as value in map must be serializable , means they should implement serailizbele interface. ex. Map<.String,String> hashmap=new HashMap<.String,String>().. here in this line ...map and string both are implictly serializable , so we dont need to implement serializble for these explicitly but if you put your own object that must be serializable.

public static void main(String arr[])
{
  Map<String,String> hashmap=new HashMap<String,String>();
 hashmap.put("key1","value1");
    hashmap.put("key2","value2");
    hashmap.put("key3","value3");
    hashmap.put("key4","value4");

     FileOutputStream fos;
    try {
        fos = new FileOutputStream("c://list.ser");

    ObjectOutputStream oos = new ObjectOutputStream(fos);
     oos.writeObject(hashmap);
     oos.close();

     FileInputStream fis = new FileInputStream("c://list.ser");
     ObjectInputStream ois = new ObjectInputStream(fis);
    Map<String,String> anotherList = (Map<String,String>) ois.readObject();

     ois.close();

     System.out.println(anotherList);

 } catch (FileNotFoundException e) {e.printStackTrace();
 } catch (IOException e) {e.printStackTrace();
    } catch (ClassNotFoundException e) {e.printStackTrace();
    }

}

Upvotes: 1

shift66
shift66

Reputation: 11958

Try to call fulsh() method for outputStreams.

    obj_out.flush();
    f_out.flush();

and close them in finally statment.

Upvotes: 0

bpgergo
bpgergo

Reputation: 16037

I suggest to use absolute path, that is something like

f_out = new FileOutputStream("/home/username/mapObject.data");

or on windows

f_out = new FileOutputStream("c:\\work\\mapObject.data");

If there was no exception thrown (System.err.print(ioe); this line did not print anything) then the file was created somewhere.

Upvotes: 1

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