一个简单的堆栈: public class SqStack { PRivate int size; private Object[] datas; private int top; public SqStack(){ this(50); size = 50; } public SqStack(int size) { this.size = size; datas = new Object[size]; top = -1; } public void push(Object data){ //... } public Object pop(){ //... } public Object getTop(){ //... } public boolean isEmpty(){ //... } } public static boolean isStackOutSequence(String str){