Java-實現棧的基本操做

實現棧操做的接口：

Stack.java

package com.wanali.java_ds.sqstack;

public interface Stack {
	public void clear();

	public boolean empty();//判斷棧是否爲空

	public int length();//求棧的長度

	public Object peek();// 取得棧頂元素

	public void push(Object x);// 向棧頂添加元素

	public Object pop();// 刪除並返回棧頂元素

	public void display();//打印棧中元素

}

SqStack.java

package com.wanali.java_ds.sqstack;

public class SqStack implements Stack {
	private Object[] elem;
	private int top;

	public SqStack(int maxsize) {
		top = 0;
		elem = new Object[maxsize];
	}

	public void clear() {
		// TODO Auto-generated method stub
		while (top != 0) {
			elem[top] = null;
			top--;
		}

	}

	public boolean empty() {
		// TODO Auto-generated method stub
		return top == 0;
	}

	public int length() {
		// TODO Auto-generated method stub
		int i = 0;
		while (top != 0) {
			i++;
			--top;

		}
		return i;
	}

	public Object peek() {
		// TODO Auto-generated method stub

		return elem[top - 1];
	}

	public void push(Object x) {
		// TODO Auto-generated method stub
		elem[top] = x;
		top++;
	}

	public Object pop() {
		// TODO Auto-generated method stub
		return elem[--top];
	}

	public void display() {

		for (int i = top - 1; i >= 0; i--) {
			System.out.println(elem[i]);
		}

	}

}

TestSqStack.java

package com.wanali.java_ds.sqstack;

public class TestSqStack {
	public static void main(String[] args) {
		SqStack stack = new SqStack(10);
		stack.push(1);
		stack.push(2);
		stack.push(3);
		stack.push(4);
		stack.display();
		System.out.println("判斷棧是否爲空：");
		System.out.println(stack.empty());
		System.out.println("刪除棧頂元素：");
		stack.pop();
		stack.display();
		System.out.println("取棧頂元素："+"\n"+stack.peek());
		System.out.println("棧的長度爲：" + "\n" + stack.length());
		System.out.println("調用clear方法清空棧：");
		stack.clear();
		stack.display();
		System.out.println("棧已被清空！！");
		System.out.println("判斷棧是否爲空：");
		System.out.println(stack.empty());

	}

}

運行結果以下：