多线程的创建方式

1、继承thread
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
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，重写call方法
CallableDemo callableDemo = new CallableDemo();
FutureTask futureTask = new FutureTask<>(callableDemo);
new Thread(futureTask).start();
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

ExecutorService executorService = Executors.newFixedThreadPool(5);