Null-safe方法调用Java7 [英] Null-safe Method invocation Java7

问题描述

我想获得有关此代码的Java7功能的详细信息

  public String getPostcode（Person person）
 {
 if（person！= null）
 {
 Address address = person.getAddress（）; 
 if（address！= null）
 {
 return address.getPostcode（）; 
} 
} 
返回null; 
} 
  

可以做这样的事情

  public String getPostcode（Person person）
 {
 return person？.getAddress（）？getPostcode（）; 
} 
  

但坦率地说，我不太清楚。请解释一下？

解决方案

作为Project Coin的一部分，Java 7提出了空安全方法调用，但它没有进入最终版本。 / p>

查看所有建议的功能，以及最终在这里选择的内容 - https://wikis.oracle.com/display/ProjectCoin/2009ProposalsTOC

---

就简化该方法而言，您可以做一些改变：

  public String getPostcode（Person person）{ 
 
 if（person == null）返回null; 
地址address = person.getAddress（）; 
返回地址！= null？ address.getPostcode（）：null; 
} 
  

我认为你不能比这更简洁明了。恕我直言，试图将该代码合并为一行，只会使代码不那么清晰，可读性也会降低。

I want to get details about this feature of Java7 like this code

public String getPostcode(Person person)
{
    if (person != null)
    {
        Address address = person.getAddress();
        if (address != null)
        {
            return address.getPostcode();
        }
    }
    return null;
}

Can be do something like this

public String getPostcode(Person person)
{
    return person?.getAddress()?.getPostcode();
}

But frankly its not much clear to me.Please explain?

解决方案

Null-safe method invocation was proposed for Java 7 as a part of Project Coin, but it didn't make it to final release.

See all the proposed features, and what all finally got selected here - https://wikis.oracle.com/display/ProjectCoin/2009ProposalsTOC

---

As far as simplifying that method is concerned, you can do a little bit change:

public String getPostcode(Person person) {

    if (person == null) return null;
    Address address = person.getAddress();
    return address != null ? address.getPostcode() : null;
}

I don't think you can get any concise and clearer than this. IMHO, trying to merge that code into a single line, will only make the code less clear and less readable.

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