This surely has been asked before, but Googling doesn't find it. Is there, in any of the standard java libraries (including apache/google/...), a static isNullOrEmpty() method for Strings?
views:
1041answers:
6
+12
A:
StringUtils.isEmpty(str)orStringUtils.isNotEmpty(str)StringUtils.isBlank(str)orStringUtils.isNotBlank(str)
from Apache commons-lang.
The difference between empty and blank is : a string consisted of whitespaces only is blank but isn't empty.
I generally prefer using apache-commons if possible, instead of writing my own utility methods, although that is also plausible for simple ones like this.
Bozho
2010-02-16 10:39:35
I was confused between the distinction between blank and empty, so I looked it up; blank means, "", null, and any amount of whitespace; empty is just "" and null.
James McMahon
2010-02-16 15:50:03
+1
A:
public static boolean isNull(String str) {
return str == null ? true : false;
}
public static boolean isNullOrBlank(String param) {
if (isNull(param) || param.trim().length() == 0) {
return true;
}
return false;
}
Yashwant Chavan
2010-02-16 10:41:45
Yashwant, you don't need the return true, return false lines: return str==null || str.trim().length()==0;
Bruno Rothgiesser
2010-02-16 10:46:20
`return str == null ? true : false;` - classic no-no. Why not `return str == null`?
Yuval A
2010-02-16 10:48:11
Why even implement the first method when you can write if (str == null)?
Adamski
2010-02-16 10:55:46
Just a note about the second method, that is not how it is implemented in the Jakarta commons, mainly because when you execute the "trim" method you are creating a new object, and in their implementation they actually traverse the string from the start, and if they find anything else than a space, they will stop the method and return true. It is probably faster and it is likely to be better on memory.It is a tiny little thing but for these reasons it is better to use an external library.
Ravi Wallau
2010-02-17 03:12:21
A:
For new projects, I've started having every class I write extend the same base class where I can put all the utility methods that are annoyingly missing from Java like this one, the equivalent for collections (tired of writing list != null && ! list.isEmpty()), null-safe equals, etc. I still use Apache Commons for the implementation but this saves a small amount of typing and I haven't seen any negative effects.
Brian Deterling
2010-02-16 14:44:30
Creating your own "Universal Base Class" is questionable on many counts, and a really limiting design strategy in a language without multiple inheritance.
Don Roby
2010-02-16 22:49:51
Java already has a universal base class called Object. I can extend my base class just as easily as that one. Like I said, I haven't seen any problems yet, but I'm interested in hearing about the potential pitfalls - maybe I'll submit an S/O question asking about it.
Brian Deterling
2010-02-17 06:15:45
A:
I've seen this method written a few times in projects I've been on but I have to say I've never written it myself, or called it either ... Generally I find null and empty are completely distinct conditions and I have no reason to ever conflate them.
EJP
2010-02-17 11:39:25
A:
You can add one
public static boolean isNullOrBlank(String param) {
return param == null || param.trim().length() == 0;
}
I have
public static boolean isSet(String param) {
// doesn't ignore spaces, but does save an object creation.
return param != null && param.length() != 0;
}
Peter Lawrey
2010-02-20 09:37:51