vector.java

来自「SRI international 发布的OAA框架软件」· Java 代码 · 共 111 行

package antlr_oaa.collections.impl;

/* ANTLR Translator Generator
 * Project led by Terence Parr at http://www.jGuru.com
 * Software rights: http://www.antlr.org/RIGHTS.html
 *
 * $Id: Vector.java,v 1.1 2002/11/08 17:37:18 agno Exp $
 */

import java.util.Enumeration;
import java.util.NoSuchElementException;
import antlr_oaa.collections.Enumerator;

public class Vector implements Cloneable {
	protected Object[] data;
	protected int lastElement = -1;

	public Vector() {
		this(10);
	}
	public Vector(int size) {
		data = new Object[size];
	}
	public synchronized void appendElement(Object o) {
		ensureCapacity(lastElement+2);
		data[++lastElement] = o;
	}
	/**
	 * Returns the current capacity of the vector.
	 */
	public int capacity() {
		return data.length;
	}
	public Object clone() {
	    Vector v=null;
	    try {
		    v = (Vector)super.clone();
	    }
	    catch (CloneNotSupportedException e) {
		    System.err.println("cannot clone Vector.super");
		    return null;
	    }
	    v.data = new Object[size()];
	    System.arraycopy(data, 0, v.data, 0, size());
	    return v;
	}
	/**
	 * Returns the element at the specified index.
	 * @param index the index of the desired element
	 * @exception ArrayIndexOutOfBoundsException If an invalid
	 * index was given.
	 */
	public synchronized Object elementAt(int i) {
		if (i >= data.length) {
			throw new ArrayIndexOutOfBoundsException(i + " >= " + data.length);
		}
		if ( i<0 ) {
			throw new ArrayIndexOutOfBoundsException(i + " < 0 ");
		}
		return data[i];
	}
	public synchronized Enumeration elements() {
		return new VectorEnumerator(this);
	}
	public synchronized void ensureCapacity(int minIndex) {
		if ( minIndex+1 > data.length ) {
			Object oldData[] = data;
			int n = data.length * 2;
			if ( minIndex+1 > n ) {
				n = minIndex+1;
			}
			data = new Object[n];
			System.arraycopy(oldData, 0, data, 0, oldData.length);
		}
	}
	public synchronized boolean removeElement(Object o) {
		// find element
		int i;
		for (i=0; i<=lastElement && data[i]!=o; i++) {
			;
		}
		if ( i<=lastElement ) { // if found it
			data[i] = null;		// kill ref for GC
			int above = lastElement - i;
			if (above > 0) {
				System.arraycopy(data, i + 1, data, i, above);
			}
			lastElement--;
			return true;
		}
		else {
			return false;
		}
	}
	public synchronized void setElementAt(Object obj, int i) {
		if (i >= data.length) {
			throw new ArrayIndexOutOfBoundsException(i + " >= " + data.length);
		}
		data[i] = obj;
		// track last element in the vector so we can append things
		if ( i>lastElement ) {
			lastElement = i;
		}
	}
	// return number of slots in the vector; e.g., you can set
	// the 30th element and size() will return 31.
	public int size() {
		return lastElement+1;
	}
}