java版数据结构与算法—栈(数组方式)

/**
 * 栈就是一组记录，表示形式先进后出
 *
 * 数组 链表 树 	适应于数据库应用中做数据记录
 * 栈和队列		1.通常情况作为程序员的工具来运用
 *              2.受限访问
 *              3.更加抽象(主要通过接口进行定义)
 *
 * 栈：数组表示
 */
class MyStack {
    private int arr[] ;
    private int maxSize;
    private int top;
    //初始化
    public MyStack(int size){
        maxSize = size;
        arr = new int[maxSize];
        top = -1;
    }
    //入栈
    public void push(int value){
        arr[++top] = value;//栈底是0下标
    }
    //出栈(查看并且删除)
    public int pop(){
        return arr[top--];
    }
    //查看
    public int peek(){
        return arr[top];
    }
    //判满
    public boolean isFull(){
        return top == maxSize - 1;
    }
    //判空
    public boolean isEmpty(){
        return top == -1;
    }

    public static void main(String[] args){
        MyStack myStack = new MyStack(5);
        if(!myStack.isFull()) myStack.push(55);
        if(!myStack.isFull()) myStack.push(88);
        if(!myStack.isFull()) myStack.push(99);
        if(!myStack.isFull()) myStack.push(66);
        if(!myStack.isFull()) myStack.push(22);
        if(!myStack.isFull()) myStack.push(77);
        if(!myStack.isFull()) myStack.push(44);
        if(!myStack.isFull()) myStack.push(11);

        while (!myStack.isEmpty()){
            int value = myStack.pop();
            System.out.print(value + " ");
        }
        System.out.println();
    }
}

字符串反转：

/**
 * 字符串反转
 */
class StringReverse {
    private char arr[];
    private int maxSize;
    private int top;
    public StringReverse(int size){
        maxSize = size;
        arr = new char[maxSize];
        top = -1;
    }
    //入栈
    public void push(char value){
        arr[++top] = value;
    }
    //出栈
    public char pop(){
        return arr[top--];
    }
    //判空
    public boolean isEmpty(){
        return top == -1;
    }
}
class Reverse{
    //反转
    public String doReverse(String str){
        String output = "";
        int size = str.length();
        StringReverse stringReverse = new StringReverse(size);
        for(int i=0;i<str.length();i++){
            char in = str.charAt(i);
            stringReverse.push(in);
        }
        while(!stringReverse.isEmpty()){
            char c = stringReverse.pop();
            output += c;
        }
        return output;
    }

    public static void main(String[] args){
        String str = "qwert y";
        Reverse reverse = new Reverse();
        String value = reverse.doReverse(str);
        System.out.println(value);
    }
}