1、繼承Thread類創建線程
Thread類本質上是實現了Runnable接口的壹個實例,代表壹個線程的實例。啟動線程的唯壹方法就是通過Thread類的start()實例方法。start()方法是壹個native方法,它將啟動壹個新線程,並執行run()方法。這種方式實現多線程很簡單,通過自己的類直接extend Thread,並復寫run()方法,就可以啟動新線程並執行自己定義的run()方法。例如:
public?class?MyThread?extends?Thread?{?public?void?run()?{?
System.out.println("MyThread.run()");?}?
}?
MyThread?myThread1?=?new?MyThread();?
MyThread?myThread2?=?new?MyThread();?
myThread1.start();?
myThread2.start();
2、實現Runnable接口創建線程
如果自己的類已經extends另壹個類,就無法直接extends Thread,此時,可以實現壹個Runnable接口,如下:
public?class?MyThread?extends?OtherClass?implements?Runnable?{?public?void?run()?{?
System.out.println("MyThread.run()");?}?
}
為了啟動MyThread,需要首先實例化壹個Thread,並傳入自己的MyThread實例:
MyThread?myThread?=?new?MyThread();?Thread?thread?=?new?Thread(myThread);?
thread.start();
事實上,當傳入壹個Runnable target參數給Thread後,Thread的run()方法就會調用target.run(),參考JDK源代碼:
public?void?run()?{?if?(target?!=?null)?{?
target.run();?}?
}
3、實現Callable接口通過FutureTask包裝器來創建Thread線程
Callable接口(也只有壹個方法)定義如下:
public?interface?Callable<V>{? V?call()?throws?Exception; }public?class?SomeCallable<V>?extends?OtherClass?implements?Callable<V>?{@Overridepublic?V?call()?throws?Exception?{//?TODO?Auto-generated?method?stub
return?null;
}
}Callable<V>?oneCallable?=?new?SomeCallable<V>();
//由Callable<Integer>創建壹個FutureTask<Integer>對象:
FutureTask<V>?oneTask?=?new?FutureTask<V>(oneCallable);
//註釋:FutureTask<Integer>是壹個包裝器,它通過接受Callable<Integer>來創建,它同時實現了Future和Runnable接口。?
//由FutureTask<Integer>創建壹個Thread對象: Thread?oneThread?=?new?Thread(oneTask); oneThread.start();//至此,壹個線程就創建完成了。