小编use*_*888的帖子

public class SieveGenerator{

static int N = 50;
public static void main(String args[]){

    int cores = Runtime.getRuntime().availableProcessors();

    int f[] = new int[N];

    //fill array with 0,1,2...f.length
    for(int j=0;j<f.length;j++){
        f[j]=j;
    }

    f[0]=0;f[1]=0;//eliminate these cases

    int p=2;

    removeNonPrime []t = new removeNonPrime[cores];

    for(int i = 0; i < cores; i++){
        t[i] = new removeNonPrime(f,p);
    }

    while(p <= (int)(Math.sqrt(N))){
        t[p%cores].start();//problem here because you cannot start a thread which has already started(IllegalThreadStateException)
        try{
            t[p%cores].join();
        }catch(Exception e){}
        //get the next prime
        p++;
        while(p<=(int)(Math.sqrt(N))&&f[p]==0)p++;
    }


    //count …

什么是原子动作以及为什么它们是必要的？另外,如何在Java中实现原子操作？

我的理解是,在编程中,原子动作是一种有效地发生在一起的动作.原子动作不能在中间停止,它要么完全发生,要么根本不发生.

例如,在线订购需要两个操作的机票:付款和座位预订.潜在的乘客必须.

1. 支付和预留座位,或者
2. 既不付钱也不预定座位

我正在尝试根据团队的ID来创建一个赛季的夹具列表.有20支球队,每周,任何一支球队只能打一次.因此,对于第一周,灯具将是(1,2),(3,4),(5,6),......,(19,20).然后是第二周,(1,3),(2,4),(5,7),......,(18,20).

是否有某种我可以做的公式可以很容易地使用灯具？也许组合不是在这里使用的最好的东西.什么是解决这个问题的最佳方法？

class FixtutreGenerator
   a = Array(1..20)
   i = 0

  while i < a.combination(2).to_a.length
    print a.combination(2).to_a[i]
    i = i + 20
 end
end

我有两个型号team和fixture.该fixture模型有两列home_team_id和away_team其中包含的外键team的主键.

我正在尝试进行选择查询,我可以使用夹具表中的home_team_id和来获取团队名称away_team_id.

class Fixture < ActiveRecord::Base
    attr_accessible :away_score, :away_team_id, :home_score, :home_team_id, :result, :week
    belongs_to :team, :class_name => Team
end

class Team < ActiveRecord::Base
    attr_accessible :form, :name
    has_many :fixtures, :class_name => Fixture, :foreign_key => :home_team_id
    has_many :fixtures, :class_name => Fixture, :foreign_key => :away_team_id
end

我是否需要在Fixtures控制器中执行SQL查询,然后如何在我的fixture视图中显示它？

这是我尝试查询但没有运气.在我的灯具秀中我有:

<p>
  <b>Home team:</b>
  <%= Team.find_by_sql("SELECT name FROM teams WHERE team.id = fixtures_home_team_id")     %>
</p>

Fetching gem metadata from https://rubygems.org/...........
Fetching gem metadata from https://rubygems.org/..
Could not find gem 'rmagick v 2.13.1 (>= 0) x86-mingw32' in the gems available o
n this machine.

嗨,我在运行bundle install时收到消息,下面是我的gemsfile

source 'https://rubygems.org'

gem 'rails', '3.2.6'

# Bundle edge Rails instead:
# gem 'rails', :git => 'git://github.com/rails/rails.git'

gem 'sqlite3'

gem 'carrierwave'
gem 'rmagick v 2.13.1'
# Gems used only for assets and not required
# in production environments by default.
group :assets do
 gem 'sass-rails',    '~> 3.2.3'
gem 'coffee-rails',  '~> 3.2.1' …