public class Run {

    public static void main(String[] args){
        CountOperate c = new CountOperate();
        Thread t1 = new Thread(c);
        System.out.println("main begin t1 isAlive = " + t1.isAlive());
        t1.setName("A");
        t1.start();
        System.out.println("main end t1 isAlive = " + t1.isAlive());
        System.out.println("main end c isAlive = " + c.isAlive());
    }
}

class CountOperate extends Thread {

    public CountOperate(){
        System.out.println("CountOperate --- begin");
        System.out.println("Thread.currentThread().getName() = " + Thread.currentThread().getName());
        System.out.println("Thread.currentThread().isAlive() = " + Thread.currentThread().isAlive());
        System.out.println("Thread.currentThread() == this : " + (Thread.currentThread() == this));
        System.out.println("this.getName = " + this.getName());
        System.out.println("this.isAlive() = " + this.isAlive());
        System.out.println("CountOperate --- end ");
    }

    @Override
    public void run() {
        System.out.println("run --- begin");
        System.out.println("Thread.currentThread().getName = " + Thread.currentThread().getName());
        System.out.println("Thread.currentThread().isAlive() = " + Thread.currentThread().isAlive());
        System.out.println("Thread.currentThread() == this : " + (Thread.currentThread() == this));
        System.out.println("this.getName() = " + this.getName());
        System.out.println("this.isAlive() = " + this.isAlive());
        System.out.println("run --- end");
    }
}

結(jié)果：

CountOperate --- begin
Thread.currentThread().getName() = main
Thread.currentThread().isAlive() = true
Thread.currentThread() == this : false
this.getName = Thread-0
this.isAlive() = false
CountOperate --- end
main begin t1 isAlive = false
main end t1 isAlive = true
main end c isAlive = false
run --- begin
Thread.currentThread().getName = A
Thread.currentThread().isAlive() = true
Thread.currentThread() == this : false
this.getName() = Thread-0
this.isAlive() = false
run --- end

根據(jù)打印的 Log 可以知道調(diào)用 CountOperate 構(gòu)造函數(shù)的是 main 線程，因此打印出：

Thread.currentThread().getName() = main
Thread.currentThread().isAlive() = true

而此時還沒有啟動 CountOperate 子線程所以打印出：

this.getName = Thread-0
this.isAlive() = false

此時 this 代表的是 CountOperate 對象實例盛嘿，所以

Thread.currentThread() == this : false

這里比較讓人疑惑的是this.getName() = Thread-0，這個 Thread-0 是什么東西
通過查看 Thread 源碼發(fā)現(xiàn)须肆，在 Thread 類的構(gòu)造方法中，會自動給 name 賦值：

public Thread() {
    init(null, null, "Thread-" + nextThreadNum(), 0);
}

然后執(zhí)行到：

Thread t1 = new Thread(c);
System.out.println("main begin t1 isAlive = " + t1.isAlive());
t1.setName("A");
t1.start();

Log 打佣タ肌：

Thread.currentThread().getName = A
Thread.currentThread().isAlive() = true
Thread.currentThread() == this : false
this.getName() = Thread-0
this.isAlive() = false

說明此時的 this 和 Thread.currentThread() 指向不是同一個線程實例

也就是說酱床，this 指向的還是 new CountOperate() 創(chuàng)建的那個線程實例 c，而不是 new Thread(thread) 創(chuàng)建的那個實例即 t1独悴。
查看源代碼可以知道：

public Thread(Runnable target) {
    init(null, target, "Thread-" + nextThreadNum(), 0);
}

實際上 new Thread(thread) 會將 thread 應(yīng)用的對象綁定到一個 private 變量 target 上
在 t1 被執(zhí)行的時候即 t1.run() 被調(diào)用的時候，它會調(diào)用 target.run() 方法
再確切的說锣尉，在 run 方法被執(zhí)行的時候刻炒，this.getName() 實際上返回的是 target.getName()，而 Thread.currentThread().getName() 實際上是 t1.getName()
因為調(diào)用 start() 的線程是 t1自沧，而不是 c坟奥，所以 this.isAlive() = false

如果修改 main 中的代碼為：

public class Run {
    public static void main(String[] args){
        CountOperate c = new CountOperate();
        c.start();
    }
}

結(jié)果：

CountOperate --- begin
Thread.currentThread().getName() = main
Thread.currentThread().isAlive() = true
Thread.currentThread() == this : false
this.getName = Thread-0
this.isAlive() = false
CountOperate --- end
run --- begin
Thread.currentThread().getName = Thread-0
Thread.currentThread().isAlive() = true
Thread.currentThread() == this : true
this.getName() = Thread-0
this.isAlive() = true
run --- end

符合預(yù)期