java数据结构----栈

1.栈，队列，优先级队列是比数组和其它数据结构更加抽象的结构，主要通过接口对栈，队列和优先级队列进行定义，这些接口表明通过他们可以完成的操作，而他们的主要实现机制对用户来说是不可见的，如栈的主要机制可以通过数组来实现，但同时也可以通过链表来实现。栈只允许访问一个数据项，即最后插入的数据项，移除该数据项之后才可以访问倒数第二个数据项，以此类推。

2.栈的代码

package com.cn.stack;
/**
 * 利用数组生成的栈，模拟栈操作
 * @author Administrator
 *
 */
public class Stackx {
private int maxsize;
private long[] stackarray;
private int top;
public Stackx(int size){
    maxsize = size;
    stackarray = new long[maxsize];
    top = -1;
}
public void push(long j){
    stackarray[++top] = j;
}
public long pop(){
    return stackarray[top --];
}
public long peek(){
    return stackarray[top];
}
public boolean isEmpty(){
    return (top == -1);
}
public boolean isFull(){
    return (top == maxsize - 1);
}
public int size(){
    return top+1;
}
}

3.栈的简单应用（检查表达式括号匹配情况）：

　　3.1.StackC.java

　　

package com.cn.stack;
/**
 * 此程序主要利用栈实现了一个匹配操作符的功能
 * @author Administrator
 *
 */
public class StackC {
private int maxsize;
private char[] stackarray;
private int top;
public StackC(int size){
    maxsize = size;
    stackarray = new char[maxsize];
    top = -1;
}
public void push(char c){
    stackarray[++ top] = c;
}
public char pop(){
    return stackarray[top --];
}
public char peek(){
    return stackarray[top];
}
public boolean isEmpty(){
    return (top == -1);
}
public boolean isFull(){
    return (top == maxsize - 1);
}
}

　　3.2.BracketChecker.java

package com.cn.stack;

public class BracketCheacker {
private String input;
public BracketCheacker(String in){
    input = in;
}
public void Cheak(){
    int stacksize = input.length();
    StackC sc = new StackC(stacksize);
    for (int i = 0; i < stacksize; i++) {
        char ch = input.charAt(i);
        switch (ch){
        case '{':
        case '[':
        case '(':
            sc.push(ch);
            break;
        case ')':
        case ']':
        case '}':
            if (!sc.isEmpty()){
                char chx = sc.pop();
                if ((ch == '{' && chx!='}')||(ch == '[' && chx !=']')||(ch == '(' && chx !=')')){
                    System.out.println("erro"+ch+"at"+i);
                }
            }else{
                System.out.println("error"+ch+"at"+i);
                break;
            }
        default:
            break;
        }
    }
    if (!sc.isEmpty()){
        System.out.println("error,missing right delimiter");
    }else{
        System.out.println("the expression passed check");
    }
}
}

　　　3.3.BracketTest.java

package com.cn.stack;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class BracketTest {
public static String getstring(){
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    String s = null;
    try {
        s = br.readLine();
    } catch (IOException e) {
    }
    return s;
}
public static void main(String[] args) {
    while (true){
        String in = getstring();
        if (in.length() != 0){
            BracketCheacker bc = new BracketCheacker(in);
            bc.Cheak();
        }
    }
}
}

4.栈操作（出入栈）的时间复杂度是O(1),特点：后入先出