myvector.java

基本的数据结构的java代码

public class MyVector{
	private Object[] elementData;
	private int elementCount;
	
	private void ensureCapacity(int minCapacity){
		int oldCapacity = elementData.length;
		if (minCapacity > oldCapacity) {
	   		Object oldData[] = elementData;
	    	int newCapacity = oldCapacity * 2;
    	    if (newCapacity < minCapacity) {
					newCapacity = minCapacity;
	    	}
	    	elementData = new Object[newCapacity];
	    	System.arraycopy(oldData, 0, elementData, 0, elementCount);
		}	
	}

	public MyVector(){
		this(10);
	}
	
	public MyVector(int initialCapacity){
		elementData = new Object[initialCapacity];
		elementCount = 0;
	}
	
	public void add(int index,Object element){
		if (index >= elementCount + 1) {
	    	throw new ArrayIndexOutOfBoundsException(index + " > " + elementCount);
		}
		ensureCapacity(elementCount + 1);
		System.arraycopy(elementData, index, elementData, index + 1, elementCount - index);
		elementData[index] = element;
		elementCount++;
	}
	
	public void add(Object element){
		add(elementCount,element);
	}
	
	public void set(int index,Object element){
		if (index >= elementCount) {
	    	throw new ArrayIndexOutOfBoundsException(index + " >= " + elementCount);
		}
		elementData[index] = element;
	}
	
	public Object get(int index){
		if (index >= elementCount)
	    	throw new ArrayIndexOutOfBoundsException(index);
		return elementData[index];
	}
	
	public int size(){
		return elementCount;
	}

	public int indexOf(Object element){
		if (element == null) {
	    	for (int i = 0 ; i < elementCount ; i++)
				if (elementData[i] == null)	 return i;
		} else {
	    	for (int i = 0 ; i < elementCount ; i++)
				if (element.equals(elementData[i]))
		    		return i;
		}
		return -1;
	}

	public boolean contain(Object element){
		return indexOf(element) >= 0;
	}

	public void remove(Object element){
		int i = indexOf(element);
		if (i >= 0) {
	    	remove(i);	    
		}
	}
	
	public void remove(int index){
		if (index >= elementCount) {
	    	throw new ArrayIndexOutOfBoundsException(index + " >= " + elementCount);
		}
		else if (index < 0) {
	    	throw new ArrayIndexOutOfBoundsException(index);
		}
		int j = elementCount - index - 1;
		if (j > 0) {
	    	System.arraycopy(elementData, index + 1, elementData, index, j);
		}
		elementCount--;
		elementData[elementCount] = null; 
	}
	
//	public void trimToSzie(){
//		int oldCapacity = elementData.length;
//		if (elementCount < oldCapacity) {
//	    	Object oldData[] = elementData;
//	    	elementData = new Object[elementCount];
//	    	System.arraycopy(oldData, 0, elementData, 0, elementCount);
//		}
//	}
	
//	public Object[] toArray(){
//		Object[] result = new Object[elementCount];
//		System.arraycopy(elementData, 0, result, 0, elementCount);
//		return result;
//	}
/*	
	public void removeAll(){
		for (int i = 0; i < elementCount; i++)
	    	elementData[i] = null;
		elementCount = 0;
	}
*/

//	public static void vectorCopy(MyVector src,int possrc,MyVector dst,int posdst,int count){
//		int length1 = src.size();
//		int length2 = dst.size();
//		if(length1 - possrc < count || length2 - posdst < count)
//			throw new ArrayIndexOutOfBoundsException(count);
//		for(int i = 0;i < src.size();i ++){
//		dst.add(src.get(i));	
//		}
//	}
	
//	public String toString(){
//		String str="";
//		for(int i = 0;i < elementCount;i ++){
//			str =  str + get(i).toString() + " ";
//		}
//		return str;
//	}
}