包装方法和包装类 [英] Wrapper methods and wrapper classes

问题描述

我目前正在准备考试，我在这篇文章的底部遇到了一个问题..它与包装方法与包装类有关.这里有区别吗?据我了解，包装器类允许将基元包装在对象中，以便将它们包含在诸如集合之类的东西中.包装类也有一堆实用方法，允许与字符串对象相互转换.我在下面有一个问题，询问包装方法并将它们与 getter/setter 方法相关联.我是否认为 set 包装器方法只是采用一个原语并将其包装在一个对象中，或者它正在做一些不同的事情?

I am working on exam prep at the moment and I came across a question down the bottom of this post..It relates to Wrapper methods Vs Wrapper classes. Is there a difference here? As I understand that wrapper classes allow primitives to be wrapped in objects so they can be included in things like collections. Wrapper classes also have a bunch of utility methods to allows to convert to and from string objects. I have a question below that asks about wrapper methods and relates them to getter/setter methods. Am I right to think that the set wrapper method is just taking a primitive and wrapping it in an object or is it doing something different?

什么是包装方法，它们何时有用?

What are wrapper methods and when are they useful?

在 City 类中编写 set/get 包装器方法，这些方法将允许直接访问其每个位置的属性，纬度和经度.例如，setLatitude:

In the City class write the set/get wrapper methods that will allow direct access to each of its location's attributes, latitude and longitude., e.g., setLatitude:

class City {
    //...

    public void setLatitude(double value) 
    {
        location.setLat(value);
    }

    //your code:
}

推荐答案

包装类是扩展特定类或原语可用性的类.以这个类为例:

A wrapper class is a class that extends the usability of a certain class or primitive. For example take this class:

public class NewBoolean{
    private boolean value = false;
    public NewBoolean(boolean state) {
        value = state;
    }
    public boolean value() {
        return value;
    }
    public void setValue(boolean value) {
        this.value = value;
    }
    public boolean isTrue() {
        return value;
    }

    public boolean isFalse() {
        return !value;
    }

    public boolean compare(boolean anotherBoolean){
       return value==anotherBoolean;
    }
}

它可以替换任何 boolean 值，并且具有可以扩展 boolean 原语可用性的新方法.

It can replace any boolean value, and has new methods that can extend the usability of a boolean primitive.

包装方法可以引用包装函数.包装方法只是调用其他方法的方法，例如，我们可能在一个类中有这两个方法:

A wrapper method could refer to a wrapper function. Wrapper methods are just methods that call other methods, for example, we might have this two methods in a class:

public void setFullScreen() { }
public void setWindowMode() { }

包装方法可能是:

public void toggleFullScreen() {
    if(fullscreen) {
         setWindowMode();
    }
    else {
         setFullScreen();
    }
}

简而言之，一个调用类中已经存在的另一个方法的方法.另一个例子是一个 setResolution(w,h); 和一个调用 setDefaultResolution() 的包装方法，后者又会调用 setResolution(DEFAULT_W,DEFAULT_H) 在里面.

In short, a method that calls another method already inside the class. Another example woud be a setResolution(w,h); and a wrapper method what calls setDefaultResolution(), which would in turn call setResolution(DEFAULT_W,DEFAULT_H) inside.

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