1.Thread中sleep方法作用是使當前線程等待，其他線程開始執行，如果有線程鎖，sleep不會讓出鎖

沒有加鎖代碼如下：

public class SynchronizedSleepMethod {public static void main(String[] args) {MoneyMethod moneyMethod = new MoneyMethod();for (int i = 0; i < 10; i++) {Thread t = new Thread(new MyThread4(moneyMethod), "t1" + i);t.start();}for (int i = 0; i < 10; i++) {Thread t = new Thread(new MyThread5(moneyMethod), "t2" + i);t.start();}}}class MyThread4 implements Runnable {MoneyMethod moneyMethod;/*** */public MyThread4(MoneyMethod moneyMethod) {// TODO Auto-generated constructor stubthis.moneyMethod = moneyMethod;}/** (non-Javadoc)* * @see java.lang.Runnable#run()*/@Overridepublic void run() {try {Thread.sleep(1000);moneyMethod.addMoney();} catch (InterruptedException e) {// TODO Auto-generated catch block e.printStackTrace();}}}class MyThread5 implements Runnable {MoneyMethod moneyMethod;/*** */public MyThread5(MoneyMethod moneyMethod) {// TODO Auto-generated constructor stubthis.moneyMethod = moneyMethod;}/** (non-Javadoc)* * @see java.lang.Runnable#run()*/@Overridepublic void run() {try {Thread.sleep(1000);moneyMethod.subMoney();} catch (InterruptedException e) {// TODO Auto-generated catch block e.printStackTrace();} // System.out.println(moneyMethod.money);// TODO Auto-generated method stub }}class MoneyMethod {int money = 200;public void addMoney() throws InterruptedException {System.out.println(Thread.currentThread().getName() + ":::run:::" + money);money++;}public void subMoney() throws InterruptedException {System.out.println(Thread.currentThread().getName() + ":::run:::" + money);money--;}}

結果如下：

t10:::run:::202
t12:::run:::202
t11:::run:::202
t13:::run:::203
t15:::run:::205
t14:::run:::204
t17:::run:::207
t19:::run:::209
t18:::run:::209
t16:::run:::207
t21:::run:::207
t24:::run:::205
t22:::run:::206
t20:::run:::206
t29:::run:::203
t28:::run:::203
t26:::run:::202
t27:::run:::201
t23:::run:::200
t25:::run:::199

加鎖代碼如下：

public class SynchronizedSleepMethod {public static void main(String[] args) {MoneyMethod moneyMethod = new MoneyMethod();for (int i = 0; i < 10; i++) {Thread t = new Thread(new MyThread4(moneyMethod), "t1" + i);t.start();}for (int i = 0; i < 10; i++) {Thread t = new Thread(new MyThread5(moneyMethod), "t2" + i);t.start();}}}class MyThread4 implements Runnable {MoneyMethod moneyMethod;/*** */public MyThread4(MoneyMethod moneyMethod) {// TODO Auto-generated constructor stubthis.moneyMethod = moneyMethod;}/** (non-Javadoc)* * @see java.lang.Runnable#run()*/@Overridepublic void run() {try {Thread.sleep(1000);moneyMethod.addMoney();} catch (InterruptedException e) {// TODO Auto-generated catch block e.printStackTrace();}}}class MyThread5 implements Runnable {MoneyMethod moneyMethod;/*** */public MyThread5(MoneyMethod moneyMethod) {// TODO Auto-generated constructor stubthis.moneyMethod = moneyMethod;}/** (non-Javadoc)* * @see java.lang.Runnable#run()*/@Overridepublic void run() {try {Thread.sleep(1000);moneyMethod.subMoney();} catch (InterruptedException e) {// TODO Auto-generated catch block e.printStackTrace();} // System.out.println(moneyMethod.money);// TODO Auto-generated method stub }}class MoneyMethod {int money = 200;public synchronized void addMoney() throws InterruptedException {money++;System.out.println(Thread.currentThread().getName() + ":::run:::" + money);}public synchronized void subMoney() throws InterruptedException {money--;System.out.println(Thread.currentThread().getName() + ":::run:::" + money);}}

結果如下：

t10:::run:::201 t18:::run:::202 t17:::run:::203 t12:::run:::204 t13:::run:::205 t14:::run:::206 t15:::run:::207 t16:::run:::208 t11:::run:::209 t19:::run:::210 t22:::run:::209 t21:::run:::208 t20:::run:::207 t25:::run:::206 t24:::run:::205 t23:::run:::204 t26:::run:::203 t27:::run:::202 t29:::run:::201 t28:::run:::200

2.Thread中join()方法阻塞調用此方法的線程(calling thread)，直到線程t完成，此線程再繼續；

沒有join()方法代碼如下：

public class JoinMethod {public static void main(String[] args) throws InterruptedException {MoneyMethod2 moneyMethod = new MoneyMethod2();for (int i = 0; i < 5; i++) {Thread t = new Thread(new MyThread4(moneyMethod), "t1" + i);t.start(); // t.join(300);System.out.println(Thread.currentThread().getName() + ":::run:::1"+i);}for (int i = 0; i < 5; i++) {Thread t = new Thread(new MyThread5(moneyMethod), "t2" + i);t.start(); // t.join(300);System.out.println(Thread.currentThread().getName() + ":::run:::2"+i);}System.out.println(Thread.currentThread().getName() + ":::finish:::");} }class MyThread4 implements Runnable {MoneyMethod2 moneyMethod;/*** */public MyThread4(MoneyMethod2 moneyMethod) {// TODO Auto-generated constructor stubthis.moneyMethod = moneyMethod;}/** (non-Javadoc)* * @see java.lang.Runnable#run()*/@Overridepublic void run() {try {Thread.sleep(2000);moneyMethod.addMoney();} catch (InterruptedException e) {// TODO Auto-generated catch block e.printStackTrace();}}}class MyThread5 implements Runnable {MoneyMethod2 moneyMethod;/*** */public MyThread5(MoneyMethod2 moneyMethod) {// TODO Auto-generated constructor stubthis.moneyMethod = moneyMethod;}/** (non-Javadoc)* * @see java.lang.Runnable#run()*/@Overridepublic void run() {try {Thread.sleep(2000);moneyMethod.subMoney();} catch (InterruptedException e) {// TODO Auto-generated catch block e.printStackTrace();} // System.out.println(moneyMethod.money);// TODO Auto-generated method stub }}class MoneyMethod2 {int money = 200;public void addMoney() throws InterruptedException {money++;System.out.println(Thread.currentThread().getName() + ":::add:::" + money);}public void subMoney() throws InterruptedException {money--;System.out.println(Thread.currentThread().getName() + ":::sub:::" + money);}}

結果：主線程會提前走掉，然后子線程執行

main:::run:::10 main:::run:::11 main:::run:::12 main:::run:::13 main:::run:::14 main:::run:::20 main:::run:::21 main:::run:::22 main:::run:::23 main:::run:::24 main:::finish::: t10:::add:::201 t12:::add:::202 t11:::add:::203 t13:::add:::204 t14:::add:::205 t21:::sub:::203 t20:::sub:::203 t24:::sub:::201 t22:::sub:::200 t23:::sub:::201

添加了join后，join的等待時間>線程執行時間，代碼如下：

public class JoinMethod {public static void main(String[] args) throws InterruptedException {MoneyMethod2 moneyMethod = new MoneyMethod2();for (int i = 0; i < 5; i++) {Thread t = new Thread(new MyThread4(moneyMethod), "t1" + i);t.start();t.join(3000);System.out.println(Thread.currentThread().getName() + ":::run:::1"+i);}for (int i = 0; i < 5; i++) {Thread t = new Thread(new MyThread5(moneyMethod), "t2" + i);t.start();t.join(3000);System.out.println(Thread.currentThread().getName() + ":::run:::2"+i);}System.out.println(Thread.currentThread().getName() + ":::finish:::");} }class MyThread4 implements Runnable {MoneyMethod2 moneyMethod;/*** */public MyThread4(MoneyMethod2 moneyMethod) {// TODO Auto-generated constructor stubthis.moneyMethod = moneyMethod;}/** (non-Javadoc)* * @see java.lang.Runnable#run()*/@Overridepublic void run() {try {Thread.sleep(2000);moneyMethod.addMoney();} catch (InterruptedException e) {// TODO Auto-generated catch block e.printStackTrace();}}}class MyThread5 implements Runnable {MoneyMethod2 moneyMethod;/*** */public MyThread5(MoneyMethod2 moneyMethod) {// TODO Auto-generated constructor stubthis.moneyMethod = moneyMethod;}/** (non-Javadoc)* * @see java.lang.Runnable#run()*/@Overridepublic void run() {try {Thread.sleep(2000);moneyMethod.subMoney();} catch (InterruptedException e) {// TODO Auto-generated catch block e.printStackTrace();} // System.out.println(moneyMethod.money);// TODO Auto-generated method stub }}class MoneyMethod2 {int money = 200;public void addMoney() throws InterruptedException {money++;System.out.println(Thread.currentThread().getName() + ":::add:::" + money);}public void subMoney() throws InterruptedException {money--;System.out.println(Thread.currentThread().getName() + ":::sub:::" + money);}}

結果如下：

t10:::add:::201 main:::run:::10 t11:::add:::202 main:::run:::11 t12:::add:::203 main:::run:::12 t13:::add:::204 main:::run:::13 t14:::add:::205 main:::run:::14 t20:::sub:::204 main:::run:::20 t21:::sub:::203 main:::run:::21 t22:::sub:::202 main:::run:::22 t23:::sub:::201 main:::run:::23 t24:::sub:::200 main:::run:::24 main:::finish:::

加入join方法后，線程執行時間>join的等待時間時，代碼如下：

public class JoinMethod {public static void main(String[] args) throws InterruptedException {MoneyMethod2 moneyMethod = new MoneyMethod2();for (int i = 0; i < 5; i++) {Thread t = new Thread(new MyThread4(moneyMethod), "t1" + i);t.start();t.join(300);System.out.println(Thread.currentThread().getName() + ":::run:::1"+i);}for (int i = 0; i < 5; i++) {Thread t = new Thread(new MyThread5(moneyMethod), "t2" + i);t.start();t.join(300);System.out.println(Thread.currentThread().getName() + ":::run:::2"+i);}System.out.println(Thread.currentThread().getName() + ":::finish:::");} }class MyThread4 implements Runnable {MoneyMethod2 moneyMethod;/*** */public MyThread4(MoneyMethod2 moneyMethod) {// TODO Auto-generated constructor stubthis.moneyMethod = moneyMethod;}/** (non-Javadoc)* * @see java.lang.Runnable#run()*/@Overridepublic void run() {try {Thread.sleep(2000);moneyMethod.addMoney();} catch (InterruptedException e) {// TODO Auto-generated catch block e.printStackTrace();}}}class MyThread5 implements Runnable {MoneyMethod2 moneyMethod;/*** */public MyThread5(MoneyMethod2 moneyMethod) {// TODO Auto-generated constructor stubthis.moneyMethod = moneyMethod;}/** (non-Javadoc)* * @see java.lang.Runnable#run()*/@Overridepublic void run() {try {Thread.sleep(2000);moneyMethod.subMoney();} catch (InterruptedException e) {// TODO Auto-generated catch block e.printStackTrace();} // System.out.println(moneyMethod.money);// TODO Auto-generated method stub }}class MoneyMethod2 {int money = 200;public void addMoney() throws InterruptedException {money++;System.out.println(Thread.currentThread().getName() + ":::add:::" + money);}public void subMoney() throws InterruptedException {money--;System.out.println(Thread.currentThread().getName() + ":::sub:::" + money);}}

結果如下：

main:::run:::10 main:::run:::11 main:::run:::12 main:::run:::13 main:::run:::14 main:::run:::20 t10:::add:::201 main:::run:::21 t11:::add:::202 main:::run:::22 t12:::add:::203 main:::run:::23 t13:::add:::204 main:::run:::24 main:::finish::: t14:::add:::205 t20:::sub:::204 t21:::sub:::203 t22:::sub:::202 t23:::sub:::201 t24:::sub:::200

在以上代碼中可以發現，在加入join()方法后主線程還是會提前走，但是所有子線程會按照執行順序執行

3.Thread.yield()方法作用是：暫停當前正在執行的線程對象，并執行其他線程，但是有一定幾率線程調度程序會將執行被暫停的線程

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轉載于:https://www.cnblogs.com/vstarcui/p/9841769.html

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