为了证明不可变对象的初始化安全性，我编写了一个小程序。即使字段是最终的，第二个线程也能够查看由第一个线程创建的半构造对象。我的概念是否错误或“对象转义”会导致它？第二个线程首先打印“10 null”，然后在迭代一半之后开始打印“10 apple”。
package test;
import java.util.ArrayList;
import java.util.List;
public final class ObjectEscape implements Runnable {
private final int a;
private final String b;
//this list is defined somewhere else
public static volatile List<ObjectEscape> globalList = new ArrayList<ObjectEscape>();
public ObjectEscape () throws InterruptedException {
a = 10;
globalList.add(this);
Thread.sleep(10);
b = "apple";
System.out.println("done");
}
public ObjectEscape(int a) {
this.a = 1;
b = "";
}
public static void main(String are[]) throws InterruptedException{
Thread t = new Thread(new ObjectEscape(1));
t.start();
ObjectEscape oe1 = new ObjectEscape();
}
@Override
public void run() {
int i=0;
while(i<10) {
if(globalList.get(0) != null)
System.out.println(globalList.get(0).a+" "+globalList.get(0).b);
i++;
}
}
}