栈的实现及应用

package com.stack.sym;

public interface MyStack<T> {
	/*
	 * 属性都是public static final。 方法都是：public abstract.
	 */
	boolean isEmpty();// 判断栈是否为空

	void clear();// 清空栈

	int length();// 计算栈的长度

	boolean push(T data);// 把数据压入到栈

	T pop();// 从栈中取出数据

}
package com.stack.sym;

public class MyArrayStack<T> implements MyStack<T> {
	private Object[] objs = new Object[16];  
    private int size = 0;  
	@Override
	public void clear() {
		for (int i = 0; i < objs.length; i++) {
			objs[i]=null;
		}
		size=0;
	}

	@Override
	public boolean isEmpty() {
		return 0==size;
	}

	@Override
	public int length() {
		return size;
	}

	@Override
	public T pop() {
		if(size==0){
			return null;
		}
		return (T) objs[--size];
	}

	@Override
	public boolean push(T data) {
		/*
		 * 询问是否需要扩容
		 */
		if (size>=objs.length) {
			resize();
		}
		objs[size++]=data;
		return true;
	}
   public void resize(){
	   Object[]temp=new Object[objs.length*3/2+1];
	   for (int i = 0; i < temp.length; i++) {
		temp[i]=objs[i];
		objs[i]=null;
	}
	   objs=temp;
   }

   @Override  
   public String toString() {  
	   StringBuffer sb = new StringBuffer();  
       sb.append("MyArrayStack: [");  
       for (int i = 0; i < size; i++) {  
           sb.append(objs[i].toString());  
           if (i != size - 1) {  
               sb.append(", ");  
           }  
       }  
       sb.append("]");  
       return sb.toString();  
   }

}
package com.stack.sym;

public class Person {
	Person(int age, String sex) {
		this.age = age;
		this.sex = sex;
	}

	private int age;
	private String sex;
}
package com.stack.sym;


public class TestStack {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		MyStack<Person> myStack = new MyArrayStack<Person>();
		myStack.push(new Person(2, "nv"));
		myStack.push(new Person(5, "man"));
		myStack.push(new Person(6, "man"));
		myStack.pop();
		myStack.toString();
		System.out.println(myStack.length());//打印为2
		System.out.println(convert(3456,4).toString());


	}
	/*
	 * 将10进制正整数num转换为n进制
	 */
	private static String convert(int mun,int n){
		MyStack<Integer>myStack=new MyArrayStack<Integer>();
		Integer result=mun;
		while(true){

			myStack.push(result%n);
			result=result/n;
			if(result%n==0){
				break;
			}
		}
		StringBuffer sBuffer=new StringBuffer();
		while(myStack.pop()!=null){
			sBuffer.append(myStack.pop());
		}
		return sBuffer.toString();
	}
	/*
	 * 遍历字符串的每一个char, 将char与栈顶元素比较. 如果char和栈顶元素配对, 则char不入栈, 
	 * 否则将char入栈. 当遍历完成时栈为空说明字符串是合法的.
	 */
	public static boolean isMatch(String str){
		MyStack<Character>myStack=new MyArrayStack<Character>() ;
		char []arr=str.toCharArray();
		for (char c:arr){
			Character temp=myStack.pop();
			if(temp==null){
				myStack.push(c);

			}
			else if(temp=='['&&c==']'){

			}else if (temp=='{'&&c=='}') {

			}else {
				myStack.push(temp);
				myStack.push(c);
			}
		}
		return myStack.isEmpty();
	}  
	/*
	 *  输入行中字符'#'表示退格, '@'表示之前的输入全都无效.
     *  使用栈保存输入的字符, 如果遇到'#'就将栈顶出栈, 如果遇到@就清空栈. 
     *  输入完成时将栈中所有字符出栈后反转就是输入的结果:
	 */
   public static String lineEdit(String input){
	   MyStack<Character>myStack=new MyArrayStack<Character>();
	   char[] arr = input.toCharArray();  
	    for (char c : arr) {  
	        if (c == '#') {  
	            myStack.pop();  
	        } else if (c == '@') {  
	            myStack.clear();  
	        } else {  
	            myStack.push(c);  
	        }  
	    }  

	    StringBuilder sb = new StringBuilder();  
	    Character temp = null;  
	    while ((temp = myStack.pop()) != null) {  
	        sb.append(temp);  
	    }  
	    // 反转字符串  
	    sb.reverse();  
	    return sb.toString();  
   }
}