The One Billion Row Challenge（十亿行挑战）

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The One Billion Row Challenge（十亿行挑战）

Your mission, should you decide to accept it, is deceptively simple: write a Java program for retrieving temperature measurement values from a text file and calculating the min, mean, and max temperature per weather station. There’s just one caveat: the file has 1,000,000,000 rows!

The text file has a simple structure with one measurement value per row:

Hamburg;12.0
Bulawayo;8.9
Palembang;38.8
St. John's;15.2
Cracow;12.6
...

The program should print out the min, mean, and max values per station, alphabetically ordered like so:

{Abha=5.0/18.0/27.4, Abidjan=15.7/26.0/34.1, Abéché=12.1/29.4/35.6, Accra=14.7/26.4/33.1, Addis Ababa=2.1/16.0/24.3, Adelaide=4.1/17.3/29.7, ...}

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编写一个Java程序，从文本文件中获取温度测量值，并计算每个气象站的最小、平均和最大温度。只有一个小问题：文件有10亿行！

文本文件的结构很简单，每行一个测量值：

Hamburg;12.0
Bulawayo;8.9
Palembang;38.8
St. John's;15.2
Cracow;12.6
...

程序应该按字母顺序打印出每个站点的最小、平均和最大值，如下所示：

{Abha=5.0/18.0/27.4, Abidjan=15.7/26.0/34.1, Abéché=12.1/29.4/35.6, Accra=14.7/26.4/33.1, Addis Ababa=2.1/16.0/24.3, Adelaide=4.1/17.3/29.7, ...}