什么案例需要Java中的同步方法访问？ [英] What Cases Require Synchronized Method Access in Java?
问题描述
在什么情况下需要同步对实例成员的访问？
我理解对类的静态成员的访问总是需要被同步 - 因为它们在类的所有对象实例之间共享。
In what cases is it necessary to synchronize access to instance members? I understand that access to static members of a class always needs to be synchronized- because they are shared across all object instances of the class.
我的问题是如果我不同步实例成员，我什么时候会不正确？
My question is when would I be incorrect if I do not synchronize instance members?
例如如果我的类是
public class MyClass {
private int instanceVar = 0;
public setInstanceVar()
{
instanceVar++;
}
public getInstanceVar()
{
return instanceVar;
}
}
c $ c> MyClass ）我需要有方法：
public synchronized setInstanceVar（）
public synchronized getInstanceVar（）？
in what cases (of usage of the class MyClass) would I need to have methods:
public synchronized setInstanceVar() and
public synchronized getInstanceVar() ?
预先感谢您的答案。
推荐答案
这取决于你是否希望你的类是线程安全的。大多数类不应该是线程安全的（为了简单），在这种情况下，您不需要同步。如果你需要它是线程安全的，你应该同步访问或使变量volatile。 （避免其他线程获得过时数据。）
It depends on whether you want your class to be thread-safe. Most classes shouldn't be thread-safe (for simplicity) in which case you don't need synchronization. If you need it to be thread-safe, you should synchronize access or make the variable volatile. (It avoids other threads getting "stale" data.)
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