Java中“包含类的子类”的含义是什么？

Question

我在阅读a paper时遇到了表达式“包含类的子类”。这在Java中是什么意思？这是报纸的摘录

Primarily, this entailed three things: (i) studying the implementation of the entity, as well as its usage, to reason about the intent behind the functionality; (ii) performing static dependency analysis on the entity, and any other types, methods, or fields referenced by it, including constants; and (iii) examining the inheritance hierarchy and subclasses of the containing class. This approach took considerable time and effort to apply.

Answer 1

由于我没有这篇论文，这是我最好的猜测：在Java中，类可以以多种方式相互关联：除了相互继承之外，类还可以嵌套在彼此内部

下面是一个从嵌套类继承的类的示例：

public class Outer {
    public void doSomething() {
        // ...does something
    }
    private static class Inner extends Outer {
        public void doSomething() {
            // ...does something else
        }
    }
}

在上面的示例中，Inner继承自Outer，它充当其包含类

Answer 2

这个例子有一个包含类的子类：

class Parent {
    class Child {
    }
}

class ParentSubclass extends Parent {
    void whatever() {
        new Child(); // Creates an instance of Parent.Child
    }
}

ParentSubclass是的子类，包含类Child。请注意，在Parent（或其子类）的之外，new Child()将不起作用，因为需要一个包含（“外部”）类来实例化非static“内部”类

当你现在将一个方法doSomething添加到Parent，在Child中调用它，但在ParentSubclass中重写它时，事情会变得有点疯狂

class Parent {
    void doSomething() {
        System.out.println("Not doing anything");
    }

    class Child {
        void whatever() {
            doSomething(); // actually: Parent.this.doSomething()
        }
    }
}

class ParentSubclass extends Parent {
    void doSomething() {
        System.out.println("I'm just slacking.");
    }

    void whatever() {
        Child a = new Child(); // Creates an instance of Parent.Child
        a.whatever(); // will print "I'm just slacking".
    }
}

这样的情况使得静态代码分析成为一个相当困难的问题