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Difference between these two conditions?可能重复：这两个条件之间的差异？
I am doing some code cleanup and NetBeans made a suggestion to change
我正在做一些代码清理，NetBeans提出了改变的建议
if(!billAddress1.equals("")) to if (!"".equals(billAddress1)).
if（！billAddress1.equals（“”））if if（！“”。equals（billAddress1））。
What is the difference between the two, and the advantages of using the suggested version over the readability of the original version?
两者之间有什么区别，以及使用建议版本优于原始版本的可读性的优势？
6 个解决方案
#1
7
billAddress1.equals("") will cause a NullPointerException if billAddress1 is null, "".equals(billAddress1) wont.
如果billAddress1为null，则billAddress1.equals（“”）将导致NullPointerException，“”。equals（billAddress1）不会。
#2
3
// Could cause a NullPointerException if billAddress1 is null
if(!billAddress1.equals(""))
// Will not cause a NullPointerException if billAddress1 is null
if (!"".equals(billAddress1))
#3
3
!"".equals(billAddress1) will never cause an NPE, so it allows a more compact syntax by allowing to get rid of the billAddress1 == null that would otherwise be required.
！“”。equals（billAddress1）永远不会导致NPE，所以它允许摆脱billAddress1 == null，否则将需要更紧凑的语法。
#4
2
The latter will not cause a Null pointer exception if the value is null.
如果值为null，后者将不会导致Null指针异常。
#5
2
One saves you from NPE as others have pointed out. But if you are sure it's not going to be null then the better way to check if a string is empty is to use the String.isEmpty() method, that's what the code seems to be trying to do.
正如其他人指出的那样，一个可以让你远离NPE。但是如果你确定它不会为null，那么检查字符串是否为空的更好方法是使用String.isEmpty（）方法，这就是代码似乎试图做的事情。
#6
1
The first one has a potential to cause NullPointerException.
第一个可能会导致NullPointerException。
#1
7
billAddress1.equals("") will cause a NullPointerException if billAddress1 is null, "".equals(billAddress1) wont.
如果billAddress1为null，则billAddress1.equals（“”）将导致NullPointerException，“”。equals（billAddress1）不会。
#2
3
// Could cause a NullPointerException if billAddress1 is null
if(!billAddress1.equals(""))
// Will not cause a NullPointerException if billAddress1 is null
if (!"".equals(billAddress1))
#3
3
!"".equals(billAddress1) will never cause an NPE, so it allows a more compact syntax by allowing to get rid of the billAddress1 == null that would otherwise be required.
！“”。equals（billAddress1）永远不会导致NPE，所以它允许摆脱billAddress1 == null，否则将需要更紧凑的语法。
#4
2
The latter will not cause a Null pointer exception if the value is null.
如果值为null，后者将不会导致Null指针异常。
#5
2
One saves you from NPE as others have pointed out. But if you are sure it's not going to be null then the better way to check if a string is empty is to use the String.isEmpty() method, that's what the code seems to be trying to do.
正如其他人指出的那样，一个可以让你远离NPE。但是如果你确定它不会为null，那么检查字符串是否为空的更好方法是使用String.isEmpty（）方法，这就是代码似乎试图做的事情。
#6
1
The first one has a potential to cause NullPointerException.
第一个可能会导致NullPointerException。