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/*
* Copyright (c) 2004 David Flanagan. All rights reserved.
* This code is from the book Java Examples in a Nutshell, 3nd Edition.
* It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied.
* You may study, use, and modify it for any non-commercial purpose,
* including teaching and use in open-source projects.
* You may distribute it non-commercially as long as you retain this notice.
* For a commercial use license, or to purchase the book,
* please visit http://www.davidflanagan.com/javaexamples3.
*/
/**
* A growable array of int values, suitable for use with multiple threads.
*/
public class ThreadSafeIntList {
protected int[] data; // This array holds the integers
protected int size; // This is how many it current holds
// Static final values are constants. This one is private.
private static final int DEFAULT_CAPACITY = 8;
// Create a ThreadSafeIntList with a default capacity
public ThreadSafeIntList() {
// We don't have to set size to zero because newly created objects
// automatically have their fields set to zero, false, and null.
data = new int[DEFAULT_CAPACITY]; // Allocate the array
}
// This constructor returns a copy of an existing ThreadSafeIntList.
// Note that it synchronizes its access to the original list.
public ThreadSafeIntList(ThreadSafeIntList original) {
synchronized (original) {
this.data = (int[]) original.data.clone();
this.size = original.size;
}
}
// Return the number of ints stored in the list
public synchronized int size() {
return size;
}
// Return the int stored at the specified index
public synchronized int get(int index) {
if (index < 0 || index >= size) // Check that argument is legitimate
throw new IndexOutOfBoundsException(String.valueOf(index));
return data[index];
}
// Append a new value to the list, reallocating if necessary
public synchronized void add(int value) {
if (size == data.length)
setCapacity(size * 2); // realloc if necessary
data[size++] = value; // add value to list
}
// Remove all elements from the list
public synchronized void clear() {
size = 0;
}
// Copy the contents of the list into a new array and return that array
public synchronized int[] toArray() {
int[] copy = new int[size];
System.arraycopy(data, 0, copy, 0, size);
return copy;
}
// Reallocate the data array to enlarge or shrink it.
// Not synchronized because it is always called from synchronized methods.
protected void setCapacity(int n) {
if (n == data.length)
return; // Check size
int[] newdata = new int[n]; // Allocate the new array
System.arraycopy(data, 0, newdata, 0, size); // Copy data into it
data = newdata; // Replace old array
}
}
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