/**
  * 模擬this逃逸
  * @author Lijian
  *
  */
 public class ThisEscape {
   //final常量會(huì)保證在構(gòu)造器內(nèi)完成初始化（但是僅限于未發(fā)生this逃逸的情況下，具體可以看多線程對final保證可見性的實(shí)現(xiàn)）
   final int i;
   //盡管實(shí)例變量有初始值，但是還實(shí)例化完成
   int j = 0;
   static ThisEscape obj;
   public ThisEscape() {
     i=1;
     j=1;
     //將this逃逸拋出給線程B
     obj = this;
   }
   public static void main(String[] args) {
     //線程A：模擬構(gòu)造器中this逃逸,將未構(gòu)造完全對象引用拋出
     /*Thread threadA = new Thread(new Runnable() {
       @Override
       public void run() {
         //obj = new ThisEscape();
       }
     });*/
     //線程B：讀取對象引用，訪問i/j變量
     Thread threadB = new Thread(new Runnable() {
       @Override
       public void run() {
               //可能會(huì)發(fā)生初始化失敗的情況解釋：實(shí)例變量i的初始化被重排序到構(gòu)造器外，此時(shí)1還未被初始化
         ThisEscape objB = obj;
         try {
           System.out.println(objB.j);
         } catch (NullPointerException e) {
           System.out.println("發(fā)生空指針錯(cuò)誤：普通變量j未被初始化");
         }
         try {
           System.out.println(objB.i);
         } catch (NullPointerException e) {
           System.out.println("發(fā)生空指針錯(cuò)誤：final變量i未被初始化");
         }
       }
     });
       //threadA.start();
       threadB.start();
   }
 }

/**
 * 模擬this逃逸
 * @author Lijian
 *
 */
public class ThisEscape {
  //final常量會(huì)保證在構(gòu)造器內(nèi)完成初始化（但是僅限于未發(fā)送this逃逸的情況下）
  final int i;
  //盡管實(shí)例變量有初始值，但是還實(shí)例化完成
  int j = 0;
  static ThisEscape obj;
  public ThisEscape() {
    i=1;
    j=1;
    //obj = this ;
  }
  public static void main(String[] args) {
    //線程A：模擬構(gòu)造器中this逃逸,將未構(gòu)造完全對象引用拋出
    Thread threadA = new Thread(new Runnable() {
      @Override
      public void run() {
        //構(gòu)造初始化中...線程B可能獲取到還未被初始化完成的變量
        //類似于this逃逸，但并不定發(fā)生
        obj = new ThisEscape();
      }
    });
    //線程B：讀取對象引用，訪問i/j變量
    Thread threadB = new Thread(new Runnable() {
      @Override
      public void run() {
        //可能會(huì)發(fā)生初始化失敗的情況解釋：實(shí)例變量i的初始化被重排序到構(gòu)造器外，此時(shí)1還未被初始化
        ThisEscape objB = obj;
        try {
          System.out.println(objB.j);
        } catch (NullPointerException e) {
          System.out.println("發(fā)生空指針錯(cuò)誤：普通變量j未被初始化");
        }
        try {
          System.out.println(objB.i);
        } catch (NullPointerException e) {
          System.out.println("發(fā)生空指針錯(cuò)誤：final變量i未被初始化");
        }
      }
    });
      threadA.start();
      threadB.start();
  }
}

/**
 * 模擬this逃逸2：構(gòu)造器中啟動(dòng)線程
 * @author Lijian
 *
 */
public class ThisEscape2 {
  final int i;
  int j;
  public ThisEscape2() {
    i = 1;
    j = 1;
    new Thread(new RunablTest()).start();
  }
  //內(nèi)部類實(shí)現(xiàn)Runnable：引用外部類
  private class RunablTest implements Runnable{
    @Override
    public void run() {
      try {
        System.out.println(ThisEscape2.this.j);
      } catch (NullPointerException e) {
        System.out.println("發(fā)生空指針錯(cuò)誤：普通變量j未被初始化");
      }
      try {
        System.out.println(ThisEscape2.this.i);
      } catch (NullPointerException e) {
        System.out.println("發(fā)生空指針錯(cuò)誤：final變量i未被初始化");
      }
    }

  }
  public static void main(String[] args) {
    new ThisEscape2();
  }
}

public class ThisEscape3 {
  private final int var;
 
  public ThisEscape3(EventSource source) {　　　　 //注冊事件，會(huì)一直監(jiān)聽，當(dāng)發(fā)生事件e時(shí)，會(huì)執(zhí)行回調(diào)函數(shù)doSomething
    source.registerListener(　　　　　　　//匿名內(nèi)部類實(shí)現(xiàn)
      new EventListener() {
        public void onEvent(Event e) {　　　　　　　　　　　 //此時(shí)ThisEscape3可能還未初始化完成，var可能還未被賦值，自然就發(fā)生嚴(yán)重錯(cuò)誤
          doSomething(e);
        }
      }
    );
    var = 10;
  }
  // 在回調(diào)函數(shù)中訪問變量
  int doSomething(Event e) {
    return var;
  }
}

...
private Thread t;
public ThisEscape2() {
  t = new Thread(new EscapeRunnable());
}

public void initStart() {
  t.start();
}
...

static{
  source.registerListener(
      new EventListener() {
        public void onEvent(Event e) {
          doSomething(e);
        }
      }
    );
    var = 10;
  }
}