You can get the first and last character of a String using charAt() method in Java. This method accepts an integer index and returns the corresponding character from String. Since Java String is backed by an array, their index is also zero-based, which means the first character resides at index zero and the last character is at index, length-1, where length is the number of characters in the String. You can get the length of String by calling the length() method. The charAt() method is not defined on java.lang.String class, but on its super interface java.lang.CharSequence, hence it will also work for StringBuffer and StringBuilder. This method returns the char value at the specified index. An index ranges from 0 to length() - 1. The first char value of the sequence is at index 0, the next at index 1, and so on, as for array indexing. If the char value specified by the index is a surrogate, the surrogate value is returned.
The find command is one of the versatile commands in UNIX and Linux and I used it a lot in my day to day work. I believe having good knowledge of find command in UNIX and understanding of its different options and usage will increase your productivity a lot in UNIX based operating system e.g. Redhat Linux or Solaris. If you are a QA, support personnel, and your works involve lots of searching text on Linux machine or if you are a Java or C++ programmer and your code resides in UNIX, find command can greatly help you to look for any word inside your source file in the absence of an IDE. It is the alternative way of searching things in UNIX, grep is another Linux command which provides similar functionality like find but in my opinion later is much more powerful than grep in UNIX.
Both array and ArrayList are two important data structure in Java and frequently used in Java programs. Even though ArrayList is internally backed by an array, knowing the difference between an array and an ArrayList in Java is critical for becoming a good Java developer. If you know the similarity and differences, you can judiciously decide when to use an array over an AraryList or vice-versa. In this article, I'll help you understand the difference between ArrayList and array in Java. If you are coming from C or C++ background then you already know that array is one of the most useful data structure in the programming world. It offers O(1) performance for index-based search and one of the fundamental way to store data.