myutil.java

本文件是设计学习的很好的书籍

package com.yuanzhen.util;

import java.math.BigDecimal;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat; 
import java.util.Date;

public class MyUtil 
{
	public static boolean isNumeric(String str)
	{
		for (int i = str.length();--i>=0;)
		{   
			if (!Character.isDigit(str.charAt(i)))
			{
				return false;
		    }
		}
		return true;
    }
	
	public static Date strChangeToDate(String str) throws ParseException
	{
		DateFormat df=new SimpleDateFormat("yy-MM-dd");   
		return df.parse(str);
	}
	
	public static String dateChangeTostr(Date date) throws ParseException
	{
		return new SimpleDateFormat("yyyy-MM-dd").format(date);
		
	}
	
	public static String addZero(String str)
	{
		String result = null;
		if(str.length()==1)
			str = "0" + str;
		result = str;
		
		return result;
	}
	
	public static String deleteZero(String str)
	{
		String result = null;
		if(str.length()==2)
		{
			String strOne = str.substring(0, 1);
			if(strOne.equals("0"))
				str = str.substring(1, str.length());
		}
		result = str;
		
		return result;
	}
	
	
	public static void main(String[] args) throws ParseException
	{
		double d = 4327854236234.4355;
		d  = MyUtil.checkDouble(d);
		System.out.println(MyUtil.doubleChangeToStr(d));
		
	}
	
	public static Double checkDouble(Double dvlaue)
	{
		 BigDecimal     b     =     new     BigDecimal(dvlaue);       
		 Double df = b.setScale(2,BigDecimal.ROUND_HALF_UP).doubleValue(); 
		 return df;
	}
	
	public static String doubleChangeToStr(Double dvlaue)
	{
		 if(dvlaue==0||dvlaue==null)
		 {
			 return "";
		 }
		 else
		 {
			 try
			 {
				 BigDecimal     b     =     new     BigDecimal(dvlaue);       
				 String df = b.setScale(2,BigDecimal.ROUND_HALF_UP).toString(); 
				 return df;
			 }
			 catch(Exception e)
			 {
				 return "";
			 }
		 }
	}

}