JAVA实现栈

package linklist;

/** * JAVA实现栈的数据结构(先进后出) * 使用数组的形式来存储 * @author zhang * */
public class Stack {
    private Object[] stackElement;
    private int length = 16;
    private int size = 0;
    private int postion = 0;   //游标位置

    public Stack(){}
    public Stack(int length){
        this.length = length;
    }

    /** * 判断是不是已经满了 * @return */
    private boolean isFul(){
        if(postion == size){
            return true;
        }else{
            return false;
        }
    }

    /** * 如果装满了，则申请新的空间，把原来的空间上的复制到新的空间 */
    private void copy(){
        Object ele[] = new Object[length+16];  //每次扩增16
        for(int i=0;i<stackElement.length;i++){
            ele[i] = stackElement[i];  //复制
        }
        this.length = length+16;
        stackElement = ele;
    }

    /** * 进栈 * @param element */
    public void push(Object element){
        if(stackElement == null){
            stackElement = new Object[length];
            stackElement[postion] = element;
            postion++;
        }else{
            if(isFul() == true){
                copy();     //创建新的空间，增加存储区域
                stackElement[postion] = element;
                postion++;
            } else {
                stackElement[postion] = element;
                postion++;
            }
        }
    }

    /** * 出栈 * @return */
    public Object pop(int pos){
        if(stackElement != null && pos>=0 && pos<=postion){
            return stackElement[pos];
        }
        return null;
    }

    /** * 遍历所有 */
    public void display(){
        for(int i=postion;i>0;i--){
            Object obj = pop(i);
            System.out.println(obj.toString());
        }
    }

    public static void main(String[] args) {
        Stack stack = new Stack();
        for(int i=0;i<10;i++){
            stack.push(i);
        }
        stack.display();

    }
}