链接在Java中调用对象和继承 [英] Chained calls to an object and inheritance in Java

问题描述

当声明链式调用的方法时，会在方法结束时返回此。

When declaring a method for chained calls usually it returns this at the end of the method.

所以我声明：

public class Foo {

    public Foo setTitle(String title){
        ...
        return this;
    }

}

并且：

public class Bar extends Foo{

      /* OTHER STUFF */
}

如果你打电话给新的Bar（）。setTitle（Test）它返回 Foo 的引用。

If you call new Bar().setTitle("Test") it returns a Foo's reference.

可以声明方法以便自动返回 Bar 的参考为了清晰，简洁和可维护性而没有覆盖Bar 中的方法？

Is possible to declare the method in order to return automatically a Bar's reference without override the method in Bar for clarity, brevity and maintainability?

谢谢

推荐答案

可以声明方法，以便自动返回Bar的引用而不覆盖Bar中的方法是为了清晰，简洁和可维护性？

Is possible to declare the method in order to return automatically a Bar's reference without override the method in Bar for clarity, brevity and maintainability?

否。你可以联系一些奇怪的泛型 - Foo< T延伸Foo> 等等 - 但这不会很令人满意。

No. You could hook up some weird generics - Foo<T extends Foo> or the like - but it wouldn't be very satisfactory.

基本上需要为this type提供一些语言支持，其中该类型的唯一有效表达式是 null 和这个。这不存在，所以你留下了重写：

Basically there's need to be some language support for "this type", where the only valid expressions of that type were null and this. That doesn't exist, so you're left with overriding:

public Bar setTitle(String title) {
    super.setTitle(title);
    return this;
}

或者：

public Bar setTitle(String title) {
    return (Bar) super.setTitle(title);
}

这只是继承最终成为痛苦的案例之一：（

It's just one of those cases where inheritance ends up being a pain :(

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