匿名内部类有类型但没有名称。

Anonymous inner classes have a type but no name.

您可以访问未由指定超类型定义的字段。但是，一旦分配给命名类型变量，接口就会丢失。

You can access fields not defined by the named supertype. However once assigned to a named type variable, the interface is lost.

显然，您可以从内部类本身访问字段。添加代码的一种方法是通过实例初始化器：

Obviously, you can access the fields from within the inner class itself. One way of adding code is through an instance initialiser:

final AtomicInteger y = new AtomicInteger();
new Runnable() {
    int x;
    {
        x = 5;
        doRun(this);
        y.set(x);
    }
    public void run() {
        ... blah ...
    }
};

匿名内部类表达式返回的值具有匿名类型，因此您有一次机会使用它在类本身之外：

The value returned by the anonymous inner class expression has the anonymous type, so you have one chance to use it outside of the class itself:

final int y = new Runnable() {
    int x;
    {
        x = 5;
        doRun(this);
    }
    public void run() {
        ... blah ...
    }
}.x;

您还可以通过类似于以下方式声明的方法传递它：

You can also pass it through a method declared similar to:

<T extends Runnable> T doRun(T runnable);