stackofintegers.java

是<java程序设计>的课后作业2-8源码.可以供初学者参考,作了解java基础语法所用.

/**
 * @(#)StackOfIntegers.java
 *
 *
 * @author 
 * @version 1.00 2009/3/18
 */


public class StackOfIntegers {
	
	private int[] elements;
	/**这里注意数组下标从0开始,
	 *而size表示栈(数组)中元素的个数,
	 *因此栈顶的元素为elements[size-1]
	*/
	private int size=0;

    /*Construct a stack with the default capacity 16*/
    public StackOfIntegers() {
    	this(16);
    }
    
    /*Construct a stack with the specified maximum capacity*/
    public StackOfIntegers(int capacity)
    {
    	elements=new int[capacity];
    }
    
    /**Push a new integer into the top of the stack*/
    public int push(int value)
    {
    	//If the stack is full,create a new one of double capacity and copy elements into the new one.
    	if(size>=elements.length)
    	{
    		int[]temp=new int [elements.length*2];
    		System.arraycopy(elements,0,temp,0,elements.length);
    		elements=temp;
    	}
    	
    	//Push the value into the stack
    	/*size先赋值,再自增*/
    	return elements[size++]=value;    	
    }
    
    /**Return and remove the top element from the stack*/
    public int pop()
    {
    	return elements[--size];
    }
    
    
    /**Return the top elements from the stack*/
    public int peek()
    {
    	return elements[size-1];
    }
    
    /**Test whether the stack is empty*/
    public boolean empty()
    {
    	return size==0;
    }
    
    /**Return the number of the elements in the stack*/
    public int getSize()
    {
    	return size;
    }
}