2018-03-01 Treadlocal类

Treadlocal类有个内置map
Treadlocal类类一旦调用set(Object)方法,以当前线程为key,存入map中,
Treadlocal类类一旦调用get()方法,以当前线程为key,拿出value;

public class Demo {
    
    static ThreadLocal t1 = new ThreadLocal();
    
    
    public static void main(String[] args) {
        
        t1.set("小异");
        
        
        new MyThread(t1).start();
        
    }

}

class MyThread extends Thread{
    
    private ThreadLocal t1;
    
    public MyThread(ThreadLocal t1) {
        
        this.t1 = t1;       
    }
    
    @Override
    public void run() {
        
        System.out.println("===== :" +t1.get());//什么都没有!!!!!!!
        
    }