【Java】 大话数据结构(6) 线性表之栈

/**
 * 栈的顺序储存结构
 * 
 * 问题：构造器中，泛型数组创建是否有更好的方法？
 * @author Yongh
 *
 */
public class SqStack<E> {
	private E[] data;
	private int top;  //栈顶指针，top=-1时为空栈
	private int maxSize;
	private static final int DEFAULT_SIZE= 10;
	
	public SqStack() {
		this(DEFAULT_SIZE);
	}
	public SqStack(int maxSize) {
		//无法创建泛型数组 data=new E[maxSize];
		data=(E[]) new Object[maxSize];
		top=-1;
		this.maxSize=maxSize;
	}
	
	public void push(E e) {
		if(top==maxSize-1) 
			throw new RuntimeException("栈已满，无法进栈！");
		top++;
		data[top]=e;
	}
	
	public E pop() {
		if(top==-1)
			throw new RuntimeException("空栈，无法出栈！");
		E e=data[top];
		top--;
		return e;
	}
	
	public void printStack() {
		if(top==-1) {
			System.out.println("空栈");			
		}else {
			for(int i=0;i<=top;i++) {
				System.out.println(data[i]);
			}
		}		
	}
}

public class StackTest {
	public static void main(String[] args) {
		SqStack<Student> sqStack=new SqStack<Student>();		
	    Student[] students= {new Student("小A",11),new Student("小B",12),new Student("小C",13),
	            new Student("小D",14),new Student("小E",151)};
	    for(int i=0;i<5;i++) {
	    	sqStack.push(students[i]);
	    }
	    sqStack.printStack();
	    for(int i=0;i<5;i++) {
	    	sqStack.pop();
	    }
	    sqStack.printStack();	    
	}       
}

class Student{
    public Student(String name, int age) {
        this.name=name;
        this.age=age;
    }
    String name;
    int age;
    public String toString() {
    	return name;
    }
}

/** 
 * 栈的顺序储存结构（两栈共享空间）
 * 
 * 注意点：栈满条件为top1+1==top2
 * 
 * @author Yongh
 *
 */
public class SqDoubleStack<E> {
	private E[] data;
	private int top1;  //栈1栈顶指针，top=-1时为空栈
	private int top2;  //栈2栈顶指针，top=maxSize-1时为空栈
	private int maxSize;
	private static final int DEFAULT_SIZE= 10;
	
	public SqDoubleStack() {
		this(DEFAULT_SIZE);
	}
	public SqDoubleStack(int maxSize) {
		//无法创建泛型数组 data=new E[maxSize];
		data=(E[]) new Object[maxSize];
		top1=-1;
		top2=maxSize-1;
		this.maxSize=maxSize;
	}
	
	/*
	 * 进栈操作，stackNumber代表要进的栈号
	 */
	public void push(int stackNumber,E e) {		
		if(top1+1==top2) 
			throw new RuntimeException("栈已满，无法进栈！");
		if(stackNumber==1) {
			data[++top1]=e;			
		}else if(stackNumber==2) {
			data[--top2]=e;			
		}else {
			throw new RuntimeException("栈号错误！");
		}

	}
	
	/*
	 * 出栈操作
	 */
	public E pop(int stackNumber) {
		E e;
		if(stackNumber==1){
			if(top1==-1)
				throw new RuntimeException("空栈1，无法出栈！");
			e=data[top1--];
		}else if(stackNumber==2) {
			if(top2==maxSize-1)
				throw new RuntimeException("空栈2，无法出栈！");
			e=data[top2++];
		}else {
			throw new RuntimeException("栈号错误！");
		}
		return e;
	}	
}

/**
 * 
 * 栈的链式存储结构
 * 
 * @author Yongh
 */
public class LinkStack<E> {
	private StackNode<E> top;
	private int count;
	
	private class StackNode<E>{
		E data;
		StackNode<E> next;
		public StackNode(E data,StackNode<E> next) {
			this.data=data;
			this.next=next;
		}
	}
	
	public LinkStack() {
		top=new StackNode<E>(null, null);
		count=0;
	}
	
	public void push(E e) {
		StackNode<E> node=new StackNode<E>(e, top);
		top=node;
		count++;
	}
	
	public E pop() {
		if(count==0)
			throw new RuntimeException("空栈，无法出栈！");
		StackNode<E> node;
		node=top;
		top=top.next;
		count--;
		E e=node.data;
		node=null;
		return e;
	}
	
	public void printStack() {
		if(count==0) {
			System.out.println("空栈");			
		}else {
			StackNode<E> node=top;
			for(int i=0;i<count;i++) {
				System.out.println(node.data);
				node=node.next;
			}
		}		
	}
	
	/*
	 * 测试代码
	 */
	public static void main(String[] args) {
		LinkStack<Student> linkStack=new LinkStack<Student>();		
	    Student[] students= {new Student("小A",11),new Student("小B",12),new Student("小C",13),
	            new Student("小D",14),new Student("小E",151)};
	    for(int i=0;i<5;i++) {
	    	linkStack.push(students[i]);
	    }
	    linkStack.printStack();	
	    System.out.println("----");
	    for(int i=0;i<5;i++) {
	    	System.out.println(linkStack.pop());
	    }
	    linkStack.printStack();	    
	}
}