Part Java I\O Part |||

In this post, I will try how to make program that java response from console, what in my concern is no matter you put any kind type data in console such char, string, and Number, we always use the same class InputStreamReader and BufferedReader, the differences is how we manipulate that data capture from console. I will start from from simple for char type.

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

public class CharacterInputDemo {

  public static void main(String[] args) throws IOException {

// TODO Auto-generated method stub

   System.out.println("Please Input Random Character : ");

    char character;

    InputStreamReader input = new InputStreamReader(System.in);

    BufferedReader buffer = new BufferedReader(input);

     character = (char) buffer.read();

 

     System.out.println("Character \'"+character+"\'");

   }

}

as we see above our input was casting to char, because every time retrieve value from BufferedReader class the data type is integer, because we want in char type then we cast integer to char. Now I will show if we want capture string type from console ok, take look code bellow:

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

public class StringInputDemo {

public static void main(String[] args) throws IOException {

   System.out.println("what is your name ? ");

   String name;

   InputStreamReader input = new InputStreamReader(System.in);

   BufferedReader buffer = new BufferedReader(input);

   name = buffer.readLine();

   System.out.println("Hello, "+name+" nice too meet you !");

   }

}

as we see above we don’t have to casting from the input that we have put because BufferedReader class have method “readLine()” to capture from console and when we retrieve automatic in string form. Now I will show how to what if put number type like integer, check out the code bellow:

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

public class NumberInputDemo {

  public static void main(String[] args) throws IOException {

   

  String temp;

  int a = 0;

  System.out.println("Pick a number please ? ");

  InputStreamReader input = new InputStreamReader(System.in);

  BufferedReader buffer = new BufferedReader(input);

  temp = buffer.readLine();

  try {

    a = Integer.parseInt(temp);

    System.out.println("the power 2 of your value "+a*a);

  }catch(NumberFormatException numberFormatException) {

  System.err.println("Data that you has put "+temp+"notnumber");

    }

  }

}

As we see above we capture value from console was same as we for string value, the difference is we convert to the format as we want and prevent if we put not in number form.