How to Deal if Java has slow Input and output classes

Just because of Java has slow Input and output classes suggested by many people for competitive programming

As following explain some ways to get over the trouble and change the conclusion from TLE to (in most cases) AC.

For all the Programs below

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Scanner Class – (easy, less typing, but not recommended very slow, refer this for reasons of slowness): In most of the cases we get TLE while using scanner class. It uses built-in nextInt(), nextLong(), nextDouble methods to read the desired object after initiating scanner object with input stream.(eg The following program many a times gets time limit exceeded conclusion and therefore not of much use.


BufferedReader – (fast, but not recommended as it requires lot of typing): The class reads text from a character-input stream, buffering characters so as to provide for the efficient reading of characters, arrays, and lines. With this method we will have to parse the value every time for desired type. Reading multiple words from single line adds to its complexity because of the use of Stringtokenizer and hence this is not recommended. This gets accepted with a running time of approx 0.89 s.but still as you can see it requires a lot of typing all together and therefore method 3 is recommended.

Userdefined FastReader Class– (which uses bufferedReader and StringTokenizer): This method uses the time advantage of BufferedReader and StringTokenizer and the advantage of user defined methods for less typing and therefore a faster input altogether. This gets accepted with a time of 1.23 s and this method is very much recommended as it is easy to remember and is fast enough to meet the needs of most of the question in competitive coding.

Using Reader Class-There is yet another fast way through the problem, I would say the fastest way but is not recommended since it requires very cumbersome methods in its implementation. It uses inputDataStream to read through the stream of data and uses read() method and nextInt() methods for taking inputs. This is by far the fastest ways of taking input but is difficult to remember and is cumbersome in its approach. Below is the sample program using this method.
This gets accepted with a surprising time of just 0.28 s. Although this is ultra fast, it is clearly not an easy method to remember.