Thread()：預設建構子，名稱是 Thread-Number
Thread(String)：給 Thread 名稱
Thread(Runnable)：給Runnable 物件
Thread(Runnable, String)：給Runnable 物件，並給 Thread 名稱
※Thread
public class ThreadTest1 extends Thread {
@Override
public void run() {
System.out.println(Thread.currentThread().getName());
}
public static void main(String... a) {
ThreadTest1 t1 = new ThreadTest1();
t1.start();
Thread t2 = new Thread(t1);
t2.start();
Thread t3 = new Thread(t1, "xxx");
t3.start();
new Thread("xxx") {
@Override
public void run() {
System.out.println(Thread.currentThread().getName());
}
}.start();
}
}
※最後是匿名寫法
※Runnable
Runnable 是個介面，因為 Thread 是 class，如果自己寫的 class 已經繼承了某個類別，那 java 就不允許再繼承了，所以可以使用 Runnablepublic class ThreadTest2 implements Runnable {
@Override
public void run() {
System.out.println(Thread.currentThread().getName());
}
public static void main(String... a) {
ThreadTest2 t1 = new ThreadTest2();
// t1.start();
Thread t2 = new Thread(t1);
t2.start();
Thread t3 = new Thread(t1, "xxx");
t3.start();
new Thread(t1, "xxx") {
@Override
public void run() {
System.out.println("t1:" + Thread.currentThread().getName());
}
}.start();
new Thread(new Runnable() {
@Override
public void run() {
System.out.println("Runnable:" + Thread.currentThread().getName());
}
}, "ooo").start();
// Java 8 的 lambda 寫法，這樣子 ThreadTest2 可以不用 implements 了
new Thread(() -> System.out.println("t1:" + Thread.currentThread().getName()), "xxx").start();
}
}
※最後兩個是匿名寫法
※Runnable 並沒有start()，所以註解打開會編譯錯誤
※Callable
此種方式是 java 1.5 增加的，實作 Runnable 要寫 run 方法；而實作 Callable 要寫 call 方法call 有例外有返回值；run 都沒有
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
public class ThreadTest3 implements Callable<String> {
@Override
public String call() throws Exception {
return Thread.currentThread().getName();
}
public static void main(String... a) {
ExecutorService service = Executors.newFixedThreadPool(1);
Future<String> future = service.submit(new ThreadTest3());
// Java 8 的 lambda 寫法，這樣子 ThreadTest3 可以不用 implements 了
// Future<String> future = service.submit(() -> Thread.currentThread().getName());
try {
String s = future.get();
System.out.println("s=" + s); // pool-1-thread-1
} catch (InterruptedException | ExecutionException e) {
e.printStackTrace();
}
List<Runnable> list = service.shutdownNow();
System.out.println(list.size());
// service.shutdown();
}
}
※
※Callable 的匿名寫法
public class ThreadTest3 {
public static void main(String... a) {
ExecutorService service = Executors.newFixedThreadPool(1);
Future<String> future = service.submit(new Callable<String>() {
@Override
public String call() {
return Thread.currentThread().getName();
}
});
try {
String s = future.get();
System.out.println("s=" + s);
} catch (InterruptedException | ExecutionException e) {
e.printStackTrace();
}
List<Runnable> list = service.shutdownNow();
System.out.println(list.size());
// service.shutdown();
}
}
※shutdown() 或 shutdownNow() 不寫也不會錯，但Eclipse裡的console，有個Terminate(正方形)會變成紅色的，表示未結束，所以要加這兩個其中之一
※shutdown() 和 shutdownNow() 的區別
shutdown 會執行完 Runnable 後才關閉shutdownNow 會馬上關閉，還沒執行的 Runnable 以 List<Runnable> 傳回。
