Can We Rely On String.isEmpty For Checking Null Condition On A String In Java?


Answer :

No, absolutely not - because if acct is null, it won't even get to isEmpty... it will immediately throw a NullPointerException.

Your test should be:

if (acct != null && !acct.isEmpty())

Note the use of && here, rather than your || in the previous code; also note how in your previous code, your conditions were wrong anyway - even with && you would only have entered the if body if acct was an empty string.

Alternatively, using Guava:

if (!Strings.isNullOrEmpty(acct))

Use StringUtils.isEmpty instead, it will also check for null.

Examples are:

 StringUtils.isEmpty(null)      = true  StringUtils.isEmpty("")        = true  StringUtils.isEmpty(" ")       = false  StringUtils.isEmpty("bob")     = false  StringUtils.isEmpty("  bob  ") = false

See more on official Documentation on String Utils.


You can't use String.isEmpty() if it is null. Best is to have your own method to check null or empty. 

public static boolean isBlankOrNull(String str) {     return (str == null || "".equals(str.trim())); }

Comments

Post a Comment

Popular posts from this blog

Converting A String To Int In Groovy

Answer : Use the toInteger() method to convert a String to an Integer , e.g. int value = "99".toInteger() An alternative, which avoids using a deprecated method (see below) is int value = "66" as Integer If you need to check whether the String can be converted before performing the conversion, use String number = "66" if (number.isInteger()) { int value = number as Integer } Deprecation Update In recent versions of Groovy one of the toInteger() methods has been deprecated. The following is taken from org.codehaus.groovy.runtime.StringGroovyMethods in Groovy 2.4.4 /** * Parse a CharSequence into an Integer * * @param self a CharSequence * @return an Integer * @since 1.8.2 */ public static Integer toInteger(CharSequence self) { return Integer.valueOf(self.toString().trim()); } /** * @deprecated Use the CharSequence version * @see #toInteger(CharSequence) */ @Deprecated public static Integer toInteger(String self) { return toInteg
Read more

"Cannot Create Cache Directory /home//.composer/cache/repo/https---packagist.org/, Or Directory Is Not Writable. Proceeding Without Cache"

Answer : if anyone pass through here, this is shorter solution: sudo chown -R $USER $HOME/.composer it seems to me the group information is missing in your command sudo chown -R <user> /home/<user>/.composer/cache/repo/https---packagist.org Shoud be sudo chown -R <user>:<group> /home/<user>/.composer/cache/repo/https---packagist.org But to avoid other permission issues, I would rather advise: sudo chown -R <user>:<group> /home/<user>/.composer/cache (you'll need access to other folders in there) and sudo chown <user>:<group> /home/<user>/.composer To make sure your user has permissions enough on the global composer folder. Mind the missing recursion so the user don't own keys created by root. If you need to find out the group: groups <user>
Read more

Android How Can I Convert A String To A Editable

Answer : As you probably found out, Editable is an interface so you cannot call new Editable() . However an Editable is nothing more than a String with Spannables, so use SpannableStringBuilder: Editable editable = new SpannableStringBuilder("Pass a string here"); If you only want to change the Spannables, never the text itself, you can use a basic SpannableString. Use Editable.Factory.getInstance().newEditable(str) From the android documentation: Returns a new SpannedStringBuilder from the specified CharSequence. You can override this to provide a different kind of Spanned.
Read more