复制堆栈和队列，而无需使用克隆。 例如，当我调用传递堆栈的方法时，我无法修改保留传递原始堆栈的权限。 我需要对传递的堆栈进行复制/克隆以更改/在方法中使用。

我只能使用Stack.java(附加)。 我创建了以下辅助方法：

public static Stack qToS(Queue q) {

Stack s = new Stack();

while (!q.isEmpty()) {

CalendarDate n = q.remove();

s.push(n);

}

return s; // Return stack s

}

public static Queue sToQ(Stack s) {

Queue q = new LinkedList();

while (!s.empty()) {

CalendarDate n = s.pop();

q.add(n);

}

return q; // Return queue q

}

/*

Provided as a Stack Class alternative

Limits user to actual Stack methods

so Vector is not available

*/

public class Stack {

// avoid blanked import of java.util

private java.util.Stack secret;

// default constructor

public Stack() {

secret = new java.util.Stack();

}

// empty that collection

public void clear() {

secret.clear();

}

// should be order constant

public int size() {

return secret.size();

}

// simply have push call push from API

public E push(E a) {

secret.push(a);

return a;

}

// And, empty calls empty from API

public boolean empty() {

return secret.empty();

}

// And my pop() uses pop() form JAVA API

public E pop() {

return secret.pop();

}

// My peek uses their peek

public E peek() {

return secret.peek();

}

// Following are not basic Stack operations

// but needed to do some simple testing

// toString is probably not O(constant)

public String toString() {

return secret.toString();

}

}

我的解决方案

public static Stack sToS(Stack orgin) {

// Create a temp stack

Stack temp = new Stack();

// Move all values from origin

// stack to temp stack using pop and push

while (!orgin.empty()) {

CalendarDate n = orgin.pop();

temp.push(n); // push here for the same order

}

// Create a copy stack

Stack copy = new Stack();

// Move all values from temp stack to

// both origin and copy stacks at the same time

while (!temp.empty()) {

CalendarDate n = temp.pop();

copy.push(n); // push here for the same order

orgin.push(n);

}

return copy;

}