怎么在Java項(xiàng)目中創(chuàng)建一個(gè)多線程

package thread;
 
import java.util.concurrent.*;
 

public class ThreadTest {
 public static void main(String[] args) throws ExecutionException, InterruptedException {
//  創(chuàng)建線程的第一種方法
  Thread1 thread1 = new Thread1();
  thread1.start();
 
//  創(chuàng)建線程的第二種方法
  Thread2 thread2 = new Thread2();
  Thread thread = new Thread(thread2);
  thread.start();
 
//  創(chuàng)建線程的第三種方法
  Callable<String> callable = new Thread3();
  FutureTask<String> futureTask = new FutureTask<>(callable);
  Thread thread3 = new Thread(futureTask);
  thread3.start();
  String s = futureTask.get();
  System.out.println(s);
 
//  創(chuàng)建線程的第四種方法
  Executor executor = Executors.newFixedThreadPool(5);
  executor.execute(new Runnable() {
   @Override
   public void run() {
    System.out.println(Thread.currentThread()+"創(chuàng)建線程的第四種方法");
   }
  });
  ((ExecutorService) executor).shutdown();
 
 }
}
class Thread1 extends Thread{
 @Override
 public void run() {
  System.out.println(Thread.currentThread()+"創(chuàng)建線程的第一種方法");
 }
}
 
class Thread2 implements Runnable {
 
 @Override
 public void run() {
  System.out.println(Thread.currentThread()+"創(chuàng)建線程的第二種方法");
 }
}
 
class Thread3 implements Callable<String> {
 
 @Override
 public String call() throws Exception {
  return Thread.currentThread()+"創(chuàng)建線程的第三種方法";
 }
}