synchronized:線程同步方法使用總結

synchronized:
   1.多線程執行同一對象的synchronized函數，線程同步正確；

實例代碼如下：
public class Test1 implements Runnable{

 //定義同一對象

static Test2 action;
 
 public static void main(String[] args) {
  // TODO Auto-generated method stub
  
  Class cls;
  try {
   cls = Class.forName("Test2");
      action = (Test2) cls.newInstance();
   Test1 t1 = new Test1();
   for (int i=0;i<1;i++){
    new Thread(t1).start();
    new Thread(t1).start();
    new Thread(t1).start();
    new Thread(t1).start();
   }
  } catch (Exception e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
 }

 public  void run() {
  // TODO Auto-generated method stub
  try {
                action.getRandomString();
   } catch (Exception e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
 }
}

public class Test2 {

 public static void main(String[] args) {

 }
    //調用同一對象的synchronized 函數，無需加statci修飾
 public  synchronized  void getRandomString() throws InterruptedException {
  System.out.println("$$$$$$$$$$$$$$$$$$");
  Thread.sleep(1000);
  Random random = new Random();  
        int aa = random.nextInt(10);
        int bb = random.nextInt(10);
        int cc = random.nextInt(10);
  System.out.println(String.valueOf(aa)+String.valueOf(bb)+String.valueOf(cc));
  System.out.println("############");
 }
}
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   2.多線程執行不同對象的synchronized函數，線程同步錯誤；

實例代碼如下：
public class Test1 implements Runnable{

 public static void main(String[] args) {
  try {
   Test1 t1 = new Test1();
   for (int i=0;i<100;i++){
    new Thread(t1).start();
    new Thread(t1).start();
    new Thread(t1).start();
    new Thread(t1).start();
   }
  } catch (Exception e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
 }

 public  void run() {
  // TODO Auto-generated method stub
  Class cls;
   try {
    cls = Class.forName("Test2");
    Test2 action = (Test2) cls.newInstance();
                action.getRandomString();
   } catch (Exception e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
 }
}

public class Test2 {

 public static void main(String[] args) {

 }
 
 /**
  * @param args
  * @throws InterruptedException
  */
 //調用不同對象的synchronized 函數，需要加statci修飾，否則線程同步失敗
 public  synchronized  void getRandomString() throws InterruptedException {
  System.out.println("$$$$$$$$$$$$$$$$$$");
  Thread.sleep(1000);
  Random random = new Random();  
        int aa = random.nextInt(10);
        int bb = random.nextInt(10);
        int cc = random.nextInt(10);
  System.out.println(String.valueOf(aa)+String.valueOf(bb)+String.valueOf(cc));
  System.out.println("############");
 }
}
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   3.多線程執行不同對象的synchronized static 函數，線程同步正確；

實例代碼如下：
public class Test1 implements Runnable{

 public static void main(String[] args) {
  try {
   Test1 t1 = new Test1();
   for (int i=0;i<100;i++){
    new Thread(t1).start();
    new Thread(t1).start();
    new Thread(t1).start();
    new Thread(t1).start();
   }
  } catch (Exception e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
 }

 public  void run() {
  // TODO Auto-generated method stub
  Class cls;
   try {
    cls = Class.forName("Test2");
    Test2 action = (Test2) cls.newInstance();
                action.getRandomString();
   } catch (Exception e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
 }
}

public class Test2 {

 public static void main(String[] args) {

 }
 
 /**
  * @param args
  * @throws InterruptedException
  */
 //調用不同對象的synchronized 函數，需要加statci修飾，否則線程同步失敗
 public  synchronized static void getRandomString() throws InterruptedException {
  System.out.println("$$$$$$$$$$$$$$$$$$");
  Thread.sleep(1000);
  Random random = new Random();  
        int aa = random.nextInt(10);
        int bb = random.nextInt(10);
        int cc = random.nextInt(10);
  System.out.println(String.valueOf(aa)+String.valueOf(bb)+String.valueOf(cc));
  System.out.println("############");
 }
}  

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