java - 如何同步父类上嵌套的Java类方法？

Question

我有两个类

public class A {
    private byte[] buf;
    public synchronized void foo() {
        // does something with buf
    }
    public class B {
        public synchronized void bar() {
            // also does something with buf
        }
    }
}

据我所知，方法 bar()在类 B 的实例上同步。如何在类 A 的对象上同步它为了保护buf ？

Answer 1

如上所述in this answer ，您可以执行以下操作:

public class A {
    private byte[] buf;

    public synchronized void foo() {
        // does something with buf
    }

    public class B {
        public void bar() {
            synchronized (A.this) {
                // also does something with buf
            }
        }
    }
}

这只有效，因为您使用的嵌套类具有对其父类的引用。但是，如果您只想同步变量 buf 的使用，您也可以这样做:

public class A {
    private byte[] buf;

    public void foo() {
        synchronized (buf) {
            // does something with buf
        }
    }

    public class B {
        public void bar() {
            synchronized (buf) {
                // also does something with buf
            }
        }
    }
}