applicationjsq.java

该程序主要用于计算样本的均值和方差

import java.io.*;
import java.util.LinkedList;

public class ApplicationJSQ {
	public double aver,sner; 
	LinkedList ll = new LinkedList();
	
	public int length()
	{
		return ll.size();
	}
/*	public static void main(String []args) throws IOException
	{
		BufferedReader br;
		br = new BufferedReader(new InputStreamReader(System.in));
		String in;
		while(!(in = br.readLine()).equals("ok"))
		{
			double d = Double.parseDouble(in);
			Double D = new Double(d);
			ll.add(D);
		}
		System.out.println("average:"+average(ll));
		System.out.println("sn2:"+ sn(ll));
		System.out.println("length:"+ll.size());
	}
	*/
	
	public void addElement(Object o)
	{
		ll.add(o);
	}
	
	public Double getElement(int p)
	{
		Double dou;
		dou = (Double)ll.get(p);
		return dou;
	}
	
	
	public double average()
	{
		double temp;
		double sum = 0;
		for(int i = 0; i < ll.size(); i++)
		{
			Double d = (Double) (ll.get(i));
			temp = d.doubleValue();
			sum += temp;
		}
		aver = sum/ll.size();
		return aver;
	}
	
	public double sn()
	{
		double temp;
		double sum = 0;
		for(int i = 0; i < ll.size(); i++)
		{
			Double d = (Double) ll.get(i);
			temp = d.doubleValue();
			double sumtemp = (temp - aver) * (temp - aver);
			sum += sumtemp;
		}
		sner = sum/ll.size();
		return sner;
	}
	
}