A collection that do not hold stored elements in memory, but serialize it into a file
/**
* created Sep 30, 2006
*
* @by Marc Woerlein (woerlein@informatik.uni-erlangen.de)
*
* Copyright 2006 Marc Woerlein
*
* This file is part of parsemis.
*
* Licence:
* LGPL: http://www.gnu.org/licenses/lgpl.html
* EPL: http://www.eclipse.org/org/documents/epl-v10.php
* See the LICENSE file in the project's top-level directory for details.
*/
//package de.parsemis.utils;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.EOFException;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.Collection;
import java.util.Iterator;
import java.util.NoSuchElementException;
/**
* This class is a collection that do not hold stored elements in memory, but
* serialize it into a file
*
* @author Marc Woerlein (woerlein@informatik.uni-erlangen.de)
*
* @param <Type>
* that is stored in the Set
*/
public class FileSerializeCollection<Type extends Serializable> implements
Collection<Type> {
protected final File file;
protected ObjectOutputStream oos;
protected int size = 0;
/**
* creates a new empty DumpSet
*
* @param file
*/
public FileSerializeCollection(final File file) {
assert (file != null) : "file == null";
this.file = file;
clear();
}
/**
* creates a new empty DumpSet
*
* @param filename
*/
public FileSerializeCollection(final String filename) {
this(new File(filename));
}
/*
* (non-Javadoc)
*
* @see java.util.Collection#add(E)
*/
public boolean add(final Type t) {
try {
oos.writeObject(t);
size++;
return true;
} catch (final IOException io) {
System.err.println(io + " " + t.toString());
}
return false;
}
/*
* (non-Javadoc)
*
* @see java.util.Collection#addAll(java.util.Collection)
*/
public boolean addAll(final Collection<? extends Type> c) {
try {
for (final Type t : c) {
oos.writeObject(t);
}
size += c.size();
return true;
} catch (final IOException io) {
System.err.println(io);
}
return false;
}
/*
* (non-Javadoc)
*
* @see java.util.Collection#clear()
*/
public void clear() {
size = 0;
try {
if (oos != null) {
oos.close();
}
oos = new ObjectOutputStream(new BufferedOutputStream(
new FileOutputStream(file)));
} catch (final IOException io) {
System.err.println(io);
}
}
/*
* (non-Javadoc)
*
* @see java.util.Collection#contains(java.lang.Object)
*/
public boolean contains(final Object o) {
throw new UnsupportedOperationException(
"contains not supported in DumpSet");
}
/*
* (non-Javadoc)
*
* @see java.util.Collection#containsAll(java.util.Collection)
*/
public boolean containsAll(final Collection<?> c) {
throw new UnsupportedOperationException(
"containsAll not supported in DumpSet");
}
/*
* (non-Javadoc)
*
* @see java.util.Collection#isEmpty()
*/
public boolean isEmpty() {
return (size == 0);
}
/*
* (non-Javadoc)
*
* @see java.util.Collection#iterator()
*/
public Iterator<Type> iterator() {
try {
oos.flush();
return new Iterator<Type>() {
private Type next = null;
private final ObjectInputStream ois = new ObjectInputStream(
new BufferedInputStream(new FileInputStream(file)));
@SuppressWarnings("unchecked")
public boolean hasNext() {
try {
if (next == null) {
next = (Type) ois.readObject();
}
} catch (final EOFException eof) {
// do not report exception
} catch (final Exception e) {
System.err.println(e);
}
try {
if (next == null) {
ois.close();
}
} catch (final IOException io) {
System.err.println(io);
}
return (next != null);
}
public Type next() {
if (hasNext()) {
final Type ret = next;
next = null;
return ret;
}
throw new NoSuchElementException("No more elements");
}
public void remove() {
throw new UnsupportedOperationException(
"remove not supported in DumpSet$iterator()");
}
};
} catch (final IOException io) {
System.err.println(io);
}
return null;
}
/*
* (non-Javadoc)
*
* @see java.util.Collection#remove(java.lang.Object)
*/
public boolean remove(final Object o) {
throw new UnsupportedOperationException(
"remove not supported in DumpSet");
}
/*
* (non-Javadoc)
*
* @see java.util.Collection#removeAll(java.util.Collection)
*/
public boolean removeAll(final Collection<?> c) {
throw new UnsupportedOperationException(
"removeAll not supported in DumpSet");
}
/*
* (non-Javadoc)
*
* @see java.util.Collection#retainAll(java.util.Collection)
*/
public boolean retainAll(final Collection<?> c) {
throw new UnsupportedOperationException(
"retainAll not supported in DumpSet");
}
/*
* (non-Javadoc)
*
* @see java.util.Collection#size()
*/
public int size() {
return size;
}
/*
* (non-Javadoc)
*
* @see java.util.Collection#toArray()
*/
public Object[] toArray() {
return toArray(new Object[size]);
}
/*
* (non-Javadoc)
*
* @see java.util.Collection#toArray(T[])
*/
@SuppressWarnings("unchecked")
public <T> T[] toArray(final T[] arg0) {
final Type[] arr = (Type[]) arg0;
int i = -1;
for (final Type v : this) {
arr[++i] = v;
}
return arg0;
}
}
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