public class Thread extends Object implements Runnable

public class FirstThread extends Thread {
  public void run(){
    for(int i=0;i<100;i++){
      /*
       * Thread类已经继承了Object
       * Object类创建了name选项 并且有其getName(),setName()方法
       * 在继承Thread的类里面使用时只需要用this引用
      */
      System.out.println(this.getName()+" "+i);
    }
  }

  public static void main(String[] args) {
    for(int i=0;i<100;i++){
      System.out.println(Thread.currentThread().getName()+" "+i);
      if(i==20){
        new FirstThread().start();
        new FirstThread().start();
      }
    }
  }

}

public Thread() 
public Thread(Runnable target) 
public Thread(Runnable target,String name)

public class SecondThread implements Runnable {
  public void run(){
    for(int i=0;i<100;i++){
      System.out.println(Thread.currentThread().getName()+" "+i);
    }
  }

  public static void main(String[] args) {
    for(int i=0;i<100;i++){
      System.out.println(Thread.currentThread().getName()+" "+i);

      if(i==20){
        SecondThread st=new SecondThread();
        //通过new Thread(target,name)创建线程
        new Thread(st,"新线程1").start();
        new Thread(st,"新线程2").start();
      }
    }
  }
}

class Thread1 extends Thread{ 
  private int count=5; 
  private String name; 
  public Thread1(String name) { 
    this.name=name; 
  } 
  public void run() { 
    for (int i = 0; i < 5; i++) { 
      System.out.println(name + "运行 count= " + count--); 
      try { 
        sleep((int) Math.random() * 10); 
      } catch (InterruptedException e) { 
        e.printStackTrace(); 
      } 
    } 

  } 
} 

public class Main { 

  public static void main(String[] args) { 
    Thread1 mTh1=new Thread1("A"); 
    Thread1 mTh2=new Thread1("B"); 
    mTh1.start(); 
    mTh2.start(); 

  } 

} 

B运行 count= 5 
A运行 count= 5 
B运行 count= 4 
B运行 count= 3 
B运行 count= 2 
B运行 count= 1 
A运行 count= 4 
A运行 count= 3 
A运行 count= 2 
A运行 count= 1

class Thread2 implements Runnable{ 
  private int count=15; 
  public void run() { 
     for (int i = 0; i < 5; i++) { 
       System.out.println(Thread.currentThread().getName() + "运行 count= " + count--); 
        try { 
          Thread.sleep((int) Math.random() * 10); 
        } catch (InterruptedException e) { 
          e.printStackTrace(); 
        } 
      } 

  } 

} 
public class Main { 

  public static void main(String[] args) { 

    Thread2 my = new Thread2(); 
      new Thread(my, "C").start();//同一个mt，但是在Thread中就不可以，如果用同一个实例化对象mt，就会出现异常   
      new Thread(my, "D").start(); 
      new Thread(my, "E").start(); 
  } 

} 

C运行 count= 15 
D运行 count= 14 
E运行 count= 13 
D运行 count= 12 
D运行 count= 10 
D运行 count= 9 
D运行 count= 8 
C运行 count= 11 
E运行 count= 12 
C运行 count= 7 
E运行 count= 6 
C运行 count= 5 
E运行 count= 4 
C运行 count= 3 
E运行 count= 2

public class ThirdThread implements Callable<Integer> {
  public Integer call(){
    int i=0;
    for(;i<100;i++){
      System.out.println(Thread.currentThread().getName()+" "+i);
    }
    return i;
  }

  public static void main(String[] args){
    ThirdThread tt=new ThirdThread();
    FutureTask<Integer> task=new FutureTask<>(tt);
    Thread t=new Thread(task,"有返回值的线程");
    for(int i=0;i<100;i++){
      System.out.println(Thread.currentThread().getName()+" "+i);
      if(i==20){
        t.start();
      }
    }
    try{
      System.out.println("返回值是："+task.get());
    }catch(Exception e){
      e.printStackTrace();
    }
  }
}

public class ThirdThread{
  public static void main(String[] args){
    ThirdThread tt=new ThirdThread();
    //先使用Lambda表达式创建Callable<Integer>对象
    //使用FutureTask封装Callable对象
    FutureTask<Integer> task=new FutureTask<Integer>((Callable<Integer>)()->{
      int i=0;
      for(;i<100;i++){
        System.out.println(Thread.currentThread().getName()+"的循环变量i的值:"+i);
      }
      return i;
    });

    for(int i=0;i<100;i++){
      System.out.println(Thread.currentThread().getName()+"的循环变量i的值:"+i);
      if(i==20){
        new Thread(task,"有返回值的线程").start();
      }
    }
    try{
      System.out.println("子线程的返回值"+task.get());
    }catch(Exception e){
      e.printStackTrace();
    }
  }
}