java - Check whether a string is not null and not empty -


how can check whether string not null , not empty?

public void dostuff(string str) {     if (str != null && str != "**here want check 'str' empty or not**")     {         /* handle empty string */     }     /* ... */ }

what isempty() ?

if(str != null && !str.isempty())

be sure use parts of && in order, because java not proceed evaluate second part if first part of && fails, ensuring not null pointer exception str.isempty() if str null.

beware, it's available since java se 1.6. have check str.length() == 0 on previous versions.

to ignore whitespace well:

if(str != null && !str.trim().isempty())

wrapped in handy function:

public static boolean empty( final string s ) {   // null-safe, short-circuit evaluation.   return s == null || s.trim().isempty(); }

becomes:

if( !empty( str ) )

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