線程的生命周期包含5個(gè)階段顾瞻，包括：新建泼疑、就緒、運(yùn)行荷荤、阻塞退渗、銷毀移稳。
★就緒狀態(tài)：創(chuàng)建了線程對(duì)象后，調(diào)用了線程的start方法会油，此時(shí)線程只是進(jìn)入了線程隊(duì)列个粱，等待獲取CPU服務(wù)啟動(dòng)，具備了運(yùn)行的條件翻翩，但是不一定已經(jīng)開(kāi)始運(yùn)行了都许；
★運(yùn)行狀態(tài)：當(dāng)就緒的線程被調(diào)度并獲得CPU資源時(shí)，便進(jìn)入運(yùn)行狀態(tài)嫂冻，run方法定義了線程的操作和功能;
★阻塞狀態(tài)：在運(yùn)行狀態(tài)的時(shí)候胶征，可能因?yàn)槟承┰驅(qū)е逻\(yùn)行狀態(tài)的線程變成了阻塞狀態(tài)，比如sleep()桨仿、wait()之后線程就處于了阻塞狀態(tài)睛低，這個(gè)時(shí)候需要其他機(jī)制將處于阻塞狀態(tài)的線程喚醒，比如調(diào)用notify或者notifyAll()方法服傍。喚醒的線程不會(huì)立刻執(zhí)行run方法钱雷，它們要再次等待CPU分配資源進(jìn)入運(yùn)行狀態(tài);
★終止?fàn)顟B(tài)：如果線程正常執(zhí)行完畢后或線程被提前強(qiáng)制性的終止或出現(xiàn)異常導(dǎo)致結(jié)束，那么線程就要被終止伴嗡，釋放資源;
notify() 和 notifyAll() 有什么區(qū)別急波？
等待池：假設(shè)一個(gè)線程A調(diào)用了某個(gè)對(duì)象的wait()方法，線程A就會(huì)釋放該對(duì)象的鎖后瘪校，進(jìn)入到了該對(duì)象的等待池，等待池中的線程不會(huì)去競(jìng)爭(zhēng)該對(duì)象的鎖名段。
鎖池：只有獲取了對(duì)象的鎖阱扬，線程才能執(zhí)行對(duì)象的 synchronized 代碼，對(duì)象的鎖每次只有一個(gè)線程可以獲得伸辟，其他線程只能在鎖池中等待
區(qū)別：
notify() 方法隨機(jī)喚醒對(duì)象的等待池中的一個(gè)線程，進(jìn)入鎖池信夫；notifyAll() 喚醒對(duì)象的等待池中的所有線程，進(jìn)入鎖池静稻。
public class TestNotifyNotifyAll {
private static Object obj = new Object();
public static void main(String[] args) {
//測(cè)試 RunnableImplA wait()
Thread t1 = new Thread(new RunnableImplA(obj));
Thread t2 = new Thread(new RunnableImplA(obj));
t1.start();
t2.start();
//RunnableImplB notify()
Thread t3 = new Thread(new RunnableImplB(obj));
t3.start();
// //RunnableImplC notifyAll()
// Thread t4 = new Thread(new RunnableImplC(obj));
// t4.start();
}
}
class RunnableImplA implements Runnable {
private Object obj;
public RunnableImplA(Object obj) {
this.obj = obj;
}
public void run() {
System.out.println("run on RunnableImplA");
synchronized (obj) {
System.out.println("obj to wait on RunnableImplA");
try {
obj.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("obj continue to run on RunnableImplA");
}
}
}
class RunnableImplB implements Runnable {
private Object obj;
public RunnableImplB(Object obj) {
this.obj = obj;
}
public void run() {
System.out.println("run on RunnableImplB");
System.out.println("睡眠3秒...");
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
synchronized (obj) {
System.out.println("notify obj on RunnableImplB");
obj.notify();
}
}
}
class RunnableImplC implements Runnable {
private Object obj;
public RunnableImplC(Object obj) {
this.obj = obj;
}
public void run() {
System.out.println("run on RunnableImplC");
System.out.println("睡眠3秒...");
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
synchronized (obj) {
System.out.println("notifyAll obj on RunnableImplC");
obj.notifyAll();
}
}
}
結(jié)果：僅調(diào)用一次 obj.notify()，線程 t1 或 t2 中的一個(gè)始終在等待被喚醒振湾，程序不終止
run on RunnableImplA
obj to wait on RunnableImplA
run on RunnableImplA
obj to wait on RunnableImplA
run on RunnableImplB
睡眠3秒...
notify obj on RunnableImplB
obj continue to run on RunnableImplA
把 t3 注掉杀迹，啟動(dòng) t4 線程押搪。調(diào)用 obj.notifyAll() 方法
public class TestNotifyNotifyAll {
private static Object obj = new Object();
public static void main(String[] args) {
//測(cè)試 RunnableImplA wait()
Thread t1 = new Thread(new RunnableImplA(obj));
Thread t2 = new Thread(new RunnableImplA(obj));
t1.start();
t2.start();
// //RunnableImplB notify()
// Thread t3 = new Thread(new RunnableImplB(obj));
// t3.start();
//RunnableImplC notifyAll()
Thread t4 = new Thread(new RunnableImplC(obj));
t4.start();
}
}
結(jié)果：t1浅碾、t2線程均可以執(zhí)行完畢
run on RunnableImplA
obj to wait on RunnableImplA
run on RunnableImplA
obj to wait on RunnableImplA
run on RunnableImplC
睡眠3秒...
notifyAll obj on RunnableImplC
obj continue to run on RunnableImplA
obj continue to run on RunnableImplA
