将对象与 null 进行比较！ [英] compare an object to null!

问题描述

我正在尝试验证对象是否为空，并且我正在使用以下语法:

I am trying to verify whether an object is null or not and i am using this syntax:

void renderSearch(Customer c){
         System.out.println("search customer rendering>...");
         try {
             if(!c.equals(null)){            
                 System.out.println("search customer  found...");
             }else{               
                 System.out.println("search customer not found...");
             }
         } catch (Exception e) {
             System.err.println ("search customer rendering error: "
                                     + e.getMessage()+"-"+e.getClass());
         }
     }

我收到以下异常:

搜索客户呈现错误:空类 java.lang.NullPointerException

search customer rendering error: null class java.lang.NullPointerException

我以为我在用 if 和 else 循环考虑这种可能性.任何帮助将不胜感激.

I thought that I was considering this possibility with my if and else loop. Any help would be appreciated.

推荐答案

在 if 语句中尝试 c != null.您不是在比较对象本身，而是在比较它们的引用.

Try c != null in your if statement. You're not comparing the objects themselves, you're comparing their references.

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