java DecimalFormat，

java DecimalFormat，

package com.suypower.chengyu.csdn;

import java.text.DecimalFormat;

public class DoubleTest {
	public static void main(String[] args) 
	{
		DoubleTest dt = new DoubleTest();
		double dou = dt.getDouble("123456.3456",2);
		System.out.println(dou);
	}
	public double getDouble(String Dtr, int i)
	{
		double d = Double.parseDouble(Dtr);
		DecimalFormat df = new DecimalFormat("##.##");
		String str = df.format(d);
		double result = Double.parseDouble(str);
		return result;
	}
}
//Java实现 字符串到实数转化的伪代码 
//Public double GetDouble( 
//String Dtr,//转换目标 
//int len//小数位长度 
//) 
//Eg  GetDouble(“123456.3456”,2) = 123456.35