用java源代码学数据结构<二>: Vector 详解(二)
(o == null) {
for (int i = index; i >= 0; i--)
if (elementData[i]==null)
return i;
} else {
for (int i = index; i >= 0; i--)
if (o.equals(elementData[i]))
return i;
}
return -1;
}
//返回指定位置对象
public synchronized E elementAt(int index) {
if (index >= elementCount) {
throw new ArrayIndexOutOfBoundsException(index + " >= " + elementCount);
}
return elementData(index);//还可以这样调用 !，这是个函数，在下面有
}
//返回vector中第一个对象
public synchronized E firstElement() {
if (elementCount == 0) {
throw new NoSuchElementException();
}
return elementData(0);
}
//返回vector中第二个对象
public synchronized E lastElement() {
if (elementCount == 0) {
throw new NoSuchElementException();
}
return elementData(elementCount - 1);
}
//设置指定位置对象的值
public synchronized void setElementAt(E obj, int index) {
if (index >= elementCount) {
throw new ArrayIndexOutOfBoundsException(index + " >= " +
elementCount);
}
elementData[index] = obj;
}
//删除指定位置对象
public synchronized void removeElementAt(int index) {
modCount++;
if (index >= elementCount) {
throw new ArrayIndexOutOfBoundsException(index + " >= " +
elementCount);
}
else if (index < 0) {
throw new ArrayIndexOutOfBoundsException(index);
}
//得到删除位置到结尾之间的距离
int j = elementCount - index - 1;
if (j > 0) {
System.arraycopy(elementData, index + 1, elementData, index, j);
}
elementCount--;
//java中不必自己删除对象（用delete用习惯了），将对象置为null即可
elementData[elementCount] = null; /* to let gc do its work */
}
public synchronized void insertElementAt(E obj, int index) {
modCount++;
if (index > elementCount) {
throw new ArrayIndexOutOfBoundsException(index
+ " > " + elementCount);
}
//扩大vector的存储空间
ensureCapacityHelper(elementCount + 1);
//多了好多的拷贝时间呀
System.arraycopy(elementData, index, elementData, index + 1, elementCount - index);
elementData[index] = obj;
elementCount++;
}
//直接在末尾添加
public synchronized void addElement(E obj) {
modCount++;
ensureCapacityHelper(elementCount + 1);
elementData[elementCount++] = obj;
}
//先找到位置，在删除对象
public synchronized boolean removeElement(Object obj) {
modCount++;
int i = indexOf(obj);
if (i >
= 0) {
removeElementAt(i);
return true;
}
return false;
}
//将对象置为null，就可以删除对象了
public synchronized void removeAllElements() {
modCount++;
// Let gc do its work
for (int i = 0; i < elementCount; i++)
elementData[i] = null;
elementCount = 0;
}
//创建并返回此对象的一个副本（不是同一个对象了）
public synchronized Object clone() {
try {
@SuppressWarnings("unchecked")
Vector v = (Vector) super.clone();
v.elementData = Arrays.copyOf(elementData, elementCount);
v.modCount = 0;
return v;
} catch (CloneNotSupportedException e) {
// this shouldn't happen, since we are Cloneable
throw new InternalError();
}
}
//得到数组的表现形式
public synchronized Object[] toArray() {
return Arrays.copyOf(elementData, elementCount);
}
//返回一个数组，包含此向量中以恰当顺序存放的所有元素；返回数组的运行时类型为指定数组的类型。
@SuppressWarnings("unchecked")
public synchronized T[] toArray(T[] a) {
if (a.length < elementCount)
return (T[]) Arrays.copyOf(elementData, elementCount, a.getClass());
System.arraycopy(elementData, 0, a, 0, elementCount);
if (a.length > elementCount)
a[elementCount] = null;
return a;
}
@SuppressWarnings("unchecked")
E elementData(int index) {
return (E) elementData[index];
}
//直接获取
public synchronized E get(int index) {
if (index >= elementCount)
throw new ArrayIndexOutOfBoundsException(index);
return elementData(index);
}
//直接设置
public synchronized E set(int index, E element) {
if (index >= elementCount)
throw new ArrayIndexOutOfBoundsException(index);
E oldValue = elementData(index);
elementData[index] = element;
return oldValue;
}
//直接增加
public synchronized boolean a