Java 自訂Stack棧類及應用

標籤：java   棧   stack   自訂   符號匹配   

棧是存放對象的一種特殊容器，在插入與刪除對象時，這種結構遵循後進先出（ Last-in-first-out，LIFO）的原則。java本身是有內建Stack類包，為了達到學習目的已經更好深入瞭解stack棧，自己動手自建java stack類是個很好的學習開始：

自建Java Stack 類

Stack 類：

package com.stack;import java.util.ArrayList;import java.util.Arrays;/** * Stack Class * @author ganyee * */public class Stack {    //Define capacity constant:CAPACITY    private static final int CAPACITY = 1024;    //Define capacity    private static int capacity;    //Define the top position of stack     //top = -1 meaning that the stack empty    private static int top = -1;    //Basic Object class array    Object[] array;    //Initialize the capacity of stack    public Stack() {        this.capacity = CAPACITY;        array = new Object[capacity];    }    //Get the size of stack    public int getSize(){        if(isEmpty()){            return 0;        }else{            return top + 1;        }    }    //Get whether stack is empty    public boolean isEmpty(){        return (top < 0);    }    //Get the top element of stack    public Object top() throws ExceptionStackEmpty{        if(isEmpty()){            throw new ExceptionStackEmpty("Stack is empty");        }        return array[top];    }    //Push element to stack    public void push(Object element) throws ExceptionStackFull{           if(getSize()== CAPACITY){               throw new ExceptionStackFull("Stack is full");           }           array[++ top] = element;    }    //Pop element from stack    public Object pop() throws ExceptionStackEmpty{        if(isEmpty()){            throw new ExceptionStackEmpty("Stack is empty");        }        return array[top --];    }    //Get the all elements of stack    public String getAllElements() throws ExceptionStackEmpty{        String[] arr = new String[top + 1];        if(!isEmpty()){            for(int i = 0;i < getSize();i ++){                arr[i] = (String)array[i];            }        }        return Arrays.toString(arr);    }}

自訂ExceptionStackEmpty異常類（關於如何自訂異常類可以看相關部落格）

package com.stack;public class ExceptionStackEmpty extends Exception {    //Constructor    public ExceptionStackEmpty(){    }    //Define myself exception construct with parameters    public ExceptionStackEmpty(String string){        super(string);    }}

自訂ExceptionStackFull異常類

package com.stack;public class ExceptionStackFull extends Exception {    //Constructor        public ExceptionStackFull(){        }        //Define myself exception construct with parameters        public ExceptionStackFull(String string){            super(string);        }}

測試類別:

package com.stack;public class StackTest {    public static void main(String[] args) {        // TODO Auto-generated method stub        Stack stack= new Stack();        System.out.println(stack.getSize());        System.out.println(stack.isEmpty());        try {            stack.push(8);            stack.push(3);            stack.push(4);            stack.push(7);            stack.push(1);            stack.push(8);            stack.push(3);            stack.push(4);            stack.push(7);            stack.push(1);            System.out.println(stack.getSize());            System.out.println(stack.top());            System.out.println(stack.getAllElements());            System.out.println(stack.pop());            System.out.println(stack.pop());            System.out.println(stack.pop());            System.out.println(stack.pop());            System.out.println(stack.pop());            System.out.println(stack.pop());            System.out.println(stack.pop());            System.out.println(stack.pop());            System.out.println(stack.pop());            System.out.println(stack.pop());        } catch (ExceptionStackFull e) {            // TODO Auto-generated catch block            e.printStackTrace();        }catch (ExceptionStackEmpty e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }}

測試結果：

0true101[8, 3, 4, 7, 1, 8, 3, 4, 7, 1]1743817438

棧的應用：符號匹配

下面，我們將藉助一個棧結構 S，通過對算術運算式自左向右的一遍掃描，檢查其中的括弧是
否匹配。
假設算術運算式為 X = “x0x1x2…xn-1”，其中 xi 可以是括弧、常數、變數名或者算術運算子。我
們依次檢查 X 中的各個符號，非括弧的符號都可以忽略。若遇到左括弧，則將其壓入棧 S 中；若遇到右括弧，則將棧頂符號彈出並與該右括弧對比。如果發現某對括弧不匹配，或者遇到右括弧時棧為空白，或者整個運算式掃描過後棧非空，都可以斷定括弧不匹配。
在按照以上規則掃描完所有字元後，若棧為空白，則說明括弧是匹配的。如果按照前面對棧的實現，每一 push()和 pop()操作都只需常數時間，因此對於長度為 n 的算術運算式，上述演算法需要運行 O(n)的時間。
該演算法的虛擬碼描述如 演算法二.1 所示：

package com.stack;public class MatchClass {    public static boolean Match(String str) throws ExceptionStackFull, ExceptionStackEmpty{        Stack stack = new Stack();        str = str.replaceAll(" ","");        char s;        for(int i = 0;i < str.length();i ++){            if(str.charAt(i) == ‘(‘ || str.charAt(i) == ‘{‘ || str.charAt(i) == ‘[‘)                stack.push(str.charAt(i));            else{                if(stack.isEmpty())                    return false;                else{                    s = str.charAt(i);                    switch(s){                    case ‘)‘:                        if((Character)stack.pop() != ‘(‘)                            return false;                        break;                    case ‘}‘:                        if((Character)stack.pop() != ‘{‘)                            return false;                        break;                    case ‘]‘:                        if((Character)stack.pop() != ‘[‘)                            return false;                        break;                    }                }            }        }        if(stack.isEmpty()){            return true;        }else{            return false;        }    }}

package com.stack;public class ParentMatch {    public static void main(String[] args) {        MatchClass match = new MatchClass();        //String str = "()({})";  //Match        //String str = "()({}) {([()[]])}";//Match        //String str = "([]{)";//Not match        //String str = ")([()] {}";//Not match        String str = "([())]{}";//Not match        try {            if(!match.Match(str)){                System.out.println(str + ": Not Macth");            }else{                System.out.println(str + ": Macth");            }        } catch (ExceptionStackFull e) {            // TODO Auto-generated catch block            e.printStackTrace();        } catch (ExceptionStackEmpty e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }}

測試結果：

()({}): Macth()({}) {([()[]])}: Macth([]{): Not Macth)([()] {}: Not Macth([())]{}: Not Macth

文章參考：資料結構與演算法（ Java 描述）鄧俊輝 著
轉載請註明出處，謝謝！
http://blog.csdn.net/github_27609763/article/details/46420149

Java 自訂Stack棧類及應用