calvalue.java

一个java源代码包

/******************************************************************
/
/队列中存放后缀表达式求值
/
*******************************************************************/

import java.io.*;

public class CalValue
{
	public static void main(String args[])throws IOException
	{
		midCal mid=new midCal();
		
		int  aa[]=new int[10];  //定义数组存放数据项
		int temp=0;				//存放数组的下标
		int pos=0;
		
	//获取表达式
	
		System.out.println("Please input the Expression: ");
		String Expression;
		InputStreamReader ir;
		BufferedReader in;
		ir=new InputStreamReader(System.in);
		in=new BufferedReader(ir);
		Expression=in.readLine();
		
		
		
		while(true)
		{
			int ch=(int)Expression.charAt(pos);
			
			if(mid.IsOperator(ch))
			{
					System.out.println("---------------Operator:-----------");
					System.out.println("the Item is: "+ch);
				   	int T1=aa[temp-1];
				   	System.out.println("T1="+T1);
				   	int T2=aa[temp];
				   	System.out.println("T2="+T2);
				   	temp=temp-1;
				   	aa[temp]=mid.TwoResult(ch,T1,T2);
				   	System.out.println("中间值为：  "+aa[temp]);
				   	pos++;
				   	System.out.println("pos= "+pos);
					System.out.println("------------------------------------");				
			}
			else
			{
				System.out.println("---------Opreand:-----------");
				temp++;
				aa[temp]=ch-48;
				System.out.println("the Item is: aa["+temp+"]="+aa[temp]);
				pos++;
				System.out.println("pos= "+pos);
				System.out.println("------------------------------------");
			}
			System.out.println("Expression's length is: "+Expression.length());
			System.out.println("temp: "+temp);
			if(pos>=Expression.length())
				break;		
		}
		System.out.print("The Expression's value is: "+aa[temp]);
						
	}
}
class midCal
{
	
	public  boolean IsOperator(int item)
	{
		if(item==43||item==45||item==42||item==47)
			return true;
		else 
			return false;
	}
	
		public  int TwoResult(int operator, int operand1,int operand2)
	{
		switch(operator)
		{
			case 43:
				return (operand1+operand2);
			case 45:
				return (operand1-operand2);
			case 42:
				return (operand1*operand2);
			case 47:
				return (operand1/operand2);	
		}
		return 0;
			
	}
}