The java.io package contains all the classes required for input and output operations. Java uses the concept of stream to make I/O operation fast.
Stream: It's called a stream because it's like a stream of water that continues to flow. A stream is a sequence of data. In Java a stream is composed of bytes. In java, 3 streams are created for us automatically.
All these streams are attached with console.
1) System.out: standard output stream
2) System.in: standard input stream
3) System.err: standard error stream
to print output and error message to the console.
1. System.out.println("simple message");
2. System.err.println("error message");
// code to get input
int i=System.in.read();//returns ASCII code of 1st character
((char) i);//will print the character
An Output Stream to write data to a destination, it may be a file,an array,
peripheral device or socket.
OutputStream class is an abstract class. It is the superclass of all classes representing an output stream of bytes.
an input stream to read data from a source, it may be a file,an array,peripheral device or socket.
InputStream class is an abstract class.It is the superclass of all
classes representing an input stream of bytes.