Files&Input Output(I/O) Stream in Java(scanner class)

Files And Input Output(I/O) Stream in Java Very Short And Important Notes 

     

Input and output(I/O) are the most commonly used operations in any program.Reading data from the keyboard and writing data on the monitor form the basic input and output operation.

Java uses streams to handle data input and output.Input streams act as sources of data and output streams act as destinations of data.The java.io package defines various classes and methods for reading and writing files and handling data streams.

Java i/o stream

Stream is a logical connection between java application and file.

Stream is nothing but a byte of data.There are three i/o stream

System.in —> Used to read the data from the keyboard

System.out —> Used to display the data on screen

System.err —> Display the error message

Every class will be available in packages. so we have to import

 the package before using those classes in our program

.All these i/o streams are available in the java.io package

Output functions

Different functions available in output stream, some functions are given below 

System.out.print() —>  Everything will be printed in a single line

Ex:- System.out.print(“welcome”);

        System.out.print(“java”);

Output is —> welcome java

System.out.println() —> The output will be printed multiple line

Ex:- System.out.println(“welcome”);

       System.out.print(“welcome”);

Output is —> welcome

                      Java

Input class and function

there are two classes read the data from keyboard

at the runtime

Scanner class —> read the data from keyboard This  class available in util package

   BufferedReader class —> in the BufferedReader to the help of

   InputStreamReader  and Filereader(read the data from either keyboard or existing file)

 This class available in io package

In order to implement this scanner class import the util package

Scanner class

a class consists of variables and methods.you can implement the variables and methods by means of object creation in a particular class.

Few methods in scanner class

nextLine() —> read string

nextInt() —> read integer

nextFloat() —> read float

nextDouble() —> read double

BufferedReaderClass in Java(I/O Stream)