java 包装方法和包装类
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Wrapper methods and wrapper classes
提问by M_x_r
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?
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，或者它是否在做一些不同的事情？
What are wrapper methods and when are they useful?
什么是包装方法，它们什么时候有用？
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:
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：
class City {
//...
public void setLatitude(double value)
{
location.setLat(value);
}
//your code:
}
回答by Basilio German
A wrapper class is a class that extends the usability of a certain class or primitive. For example take this class:
包装类是扩展某个类或原语的可用性的类。例如拿这个类：
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;
}
}
It can replace any booleanvalue, and has new methods that can extend the usability of a booleanprimitive.
它可以替换任何boolean值，并具有可以扩展boolean原语可用性的新方法。
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:
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：
public void setFullScreen() { }
public void setWindowMode() { }
And a wrapper method might be:
包装方法可能是：
public void toggleFullScreen() {
if(fullscreen) {
setWindowMode();
}
else {
setFullScreen();
}
}
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.
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 asetResolution(w,h);和一个包装方法 what 调用setDefaultResolution()，然后调用setResolution(DEFAULT_W,DEFAULT_H)内部。
回答by Robin
I heard the term 'wrapper class' being used as a synonym for a decorator class (see the 'decorator pattern') which has more usages then just allowing primitive types to be inserted into a Collection
我听说术语“包装器类”被用作装饰器类的同义词（请参阅“装饰器模式”），它的用法更多，然后只允许将基本类型插入到集合中
