多线程实现的四种方法

1) 继承Thread类

public class TestThread {
     public static void main(String[] args) {
         ThreadDemo threadDemo = new ThreadDemo();
         threadDemo.start();
     }
}
 
 
class  ThreadDemo extends Thread{
 
    @Override
    public void run() {
        boolean flag = false;
        for(int i  = 3 ; i < 100 ; i ++) {
            flag = false;
            for(int j = 2; j <= Math.sqrt(i) ; j++) {
                if(i % j == 0) {
                    flag = true;
                    break;
                }
            }
            if(flag == false) {
                System.out.print(i+"  ");
            }
        }
    }
  
     
}

2）实现Runnable接口

public class TestRunnable {
    public static void main(String[] args) {
        RunnableDemo runnableDemo = new RunnableDemo();
        new Thread(runnableDemo).start();
    }
}
 
class RunnableDemo implements Runnable{
 
    @Override
    public void run() {
        boolean flag = false;
        for(int i  = 3 ; i < 100 ; i ++) {
            flag = false;
            for(int j = 2; j <= Math.sqrt(i) ; j++) {
                if(i % j == 0) {
                    flag = true;
                    break;
                }
            }
            if(flag == false) {
                System.out.print(i+"  ");
            }
        }
    }
    
}

3）实现Callable接口

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executors;
import java.util.concurrent.FutureTask;
 
public class TestCallable1 {
    public static void main(String[] args) throws InterruptedException, ExecutionException {
        CallableDemo callableDemo = new CallableDemo();
        FutureTask futureTask = new FutureTask<>(callableDemo); 
        new Thread(futureTask).start();
        List<Integer> lists = (List<Integer>)futureTask.get(); //获取返回值
        for (Integer integer : lists) {
            System.out.print(integer + "  ");
        }
    }
}
 
class CallableDemo implements Callable<List<Integer>>{
 
    @Override
    public List<Integer> call() throws Exception {
        boolean flag = false;
        List<Integer> lists = new ArrayList<>();
        for(int i  = 3 ; i < 100 ; i ++) {
            flag = false;
            for(int j = 2; j <= Math.sqrt(i) ; j++) {
                if(i % j == 0) {
                    flag = true;
                    break;
                }
            }
            if(flag == false) {
                lists.add(i);
            }
        }
        return lists;
    }
    
}

4) 线程池

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
 
public class TestThreadPool {
    public static void main(String[] args) throws InterruptedException, ExecutionException {
        ExecutorService executorService = Executors.newFixedThreadPool(5);
        List<Future<List<Integer>>> ints = new ArrayList<>();
        for(int i = 0 ; i < 5; i ++) {
            Future<List<Integer>> future = executorService.submit(new Callable<List<Integer>>() {
                @Override
                public List<Integer> call() throws Exception {
                    boolean flag = false;
                    System.out.println(Thread.currentThread().getName()+"  ");
                    List<Integer> lists = new ArrayList<>();
                    for(int i  = 3 ; i < 100 ; i ++) {
                        flag = false;
                        for(int j = 2; j <= Math.sqrt(i) ; j++) {
                            if(i % j == 0) {
                                flag = true;
                                break;
                            }
                        }
                        if(flag == false) {
                            lists.add(i);
                        }
                    }
                    return lists;
                }
            });
            ints.add(future);
        }
        
        for (Future<List<Integer>> future : ints) {
            System.out.println(future.get());
        }
    }
}
 
class ThreadPoolDemo {
 
}