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I'm curious why the String.indexOf is returning a 0 (instead of -1) when asking for the index of an empty string within a string.
The Javadocs only say this method returns the index in this string of the specified string, -1 if the string isn't found.
To me this behavior seems highly unexpected, I would have expected a -1. Any ideas why this unexpected behavior is going on? I would at the least think this is worth a note in the method's Javadocs...
System.out.println("FOO".indexOf("")); // outputs 0 wtf!!! System.out.println("FOO".indexOf("bar")); // outputs -1 as expected System.out.println("FOO".indexOf("F")); // outputs 0 as expected System.out.println("".indexOf("")); // outputs 0 as expected, I think 
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The empty string can be found specifically at index zero of any string, because why not? In other words, if not at index zero, then at which index? Index zero is as good as any other index, and index zero is guaranteed to be a valid index for all strings except for the trifling exception of the empty string.
Java String isEmpty() Method The isEmpty() method checks whether a string is empty or not. This method returns true if the string is empty (length() is 0), and false if not.
Use String. isEmpty(), or StringUtils. isEmpty(String str) if you need a null check.
The Java programming language distinguishes between null and empty strings. An empty string is a string instance of zero length, whereas a null string has no value at all. An empty string is represented as "" . It is a character sequence of zero characters.
The empty string is everywhere, and nowhere. It is within all strings at all times, permeating the essence of their being, yet as you seek it you shall never catch a glimpse.
How many empty strings can you fit at the beginning of a string? Mu
The student said to the teacher,
Teacher, I believe that I have found the nature of the empty string. The empty string is like a particle of dust, and it floats freely through a string as dust floats freely through the room, glistening in a beam of sunlight.
The teacher responded to the student,
Hmm. A fine notion. Now tell me, where is the dust, and where is the sunlight?
The teacher struck the student with a strap and instructed him to continue his meditation.
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