Java – IO Streams

IO Streams:

• Stream is a flow of data
• IO streams are used to send and receive the information from Primary to Secondary memory or vice versa.
• java.io package is providing classes and interfaces to implement IO Streams.

Java supports:

1. Byte streams
2. Character streams
3. Buffered Streams
4. Data streams
5. Console streams
6. Object streams (Serialization and De-serialization)
7. Array streams

Console Streams:

• Console is a User screen.
• Console object is Fixed and Pre-defined.
• We can read input from the console in CUI(console based) applications.
• java.lang.System class providing functionality to get the console object.

class System
{
	public static Console console()
	{
		Returns Console object.
	}
}

Using Console object functionality we can read different types of input.

class Console
{
	public String readLine()
	{
		Reads a single line of text from the console.
	}
}

Example code:

import java.io.Console;
class ConsoleRead 
{
	public static void main(String[] args) 
	{
		Console con = System.console();
		System.out.println("Enter any input : ");
		String val = con.readLine();
		System.out.println("Input is : " + val);
	}
}

• In Console based applications, we use authentication(user, password) to work with the application.
• Console object contains readPassword() method.

class Console
{
	public char[] readPassword()
	{
		Read and return password.
	}
}

We can construct String object from char[] in many ways.

class String
{
	public static String valueOf(char[] data)
	{
		Converts char[ ] into String object.
	}
}

Code program:

import java.io.Console ;
class LoginFile 
{
	public static void main(String[] args) 
	{
		Console con = System.console();

		System.out.print("Enter Username : ");
		String uname = con.readLine();

		System.out.print("Enter Password : ");
		char data[] = con.readPassword();
		String pwd = String.valueOf(data);

		if(uname.equals("srinivas") && pwd.equals("abc123$"))
			System.out.println("Login success...");
		else
			System.out.println("Authentication failed...");
	}
}