如何在StringBuilder上检查null？ [英] How to check null on StringBuilder?

问题描述

我想在我的代码中专门检查null或为空。对于Java中的 StringBuilder ，empty和null是否相同？

I want to check for null or empty specifically in my code. Does empty and null are same for StringBuilder in Java?

例如：

StringBuilder state = new StringBuilder();
StringBuilder err= new StringBuilder(); 
success = executeCommand(cmd, state, err); 

/* here executeCommand() returns empty or null in state, I cant  make changes in  <br/> executeCommand() so can I check it in my code somehow for state, if its null or empty? */<br/>

if (state == null) { //do blabla1 }
if (state.tostring().equals("")) { //do blabla2 }

以上代码是否有意义或我应该如何更改？

Does above code make sense or how should I change it?

推荐答案

不， null 和空与 StringBuilder 。

StringBuilder nullBuilder = null;
if(nullBuilder == null) {
    System.out.println("Builder is null");
}

&

StringBuilder emptyBuilder = new StringBuilder("");
if(emptyBuilder == null || emptyBuilder.toString().equals("")) {
    System.out.println("Builder is empty");
}

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