File in Java how to Read and Write File in Java

You can use class in package java.io.* to manage file with java
for example below

Example code for read file line by line with Java

  FileInputStream fs = new FileInputStream("filename.txt"); 
  DataInputStream ds = new DataInputStream(fs);
  BufferedReader br = new BufferedReader(new InputStreamReader(ds));
  String tmp; 
  while ((tmp = br.readLine()) != null)   {
      System.out.println (tmp);
  } 
  ds.close();

Example code for Write file with java
  FileWriter fw = new FileWriter("file_name.txt");
  BufferedWriter out = new BufferedWriter(fw);
  out.write("Test Wrrite1");
  out.write("Test Wrrite2");
  out.write("Test Wrrite3");  
  out.close();

Java Class is based for Java OOP

Class is the blueprint to create Object  Class is learning the basics of OOP that everyone must know.

for example

Object of  Class Car is  My car .

Class structure

prefix eg.(public,protected) class ClassName {
  
}

public class MyClass{
 //implement some things
}

Java Date Format with SimpleDateFormat

Today I will present how to Format Date with java.text.* package
Class java.text.SimpleDateFormat  for example below

   Date date=new Date();
        System.out.println("No format :"+date);
        java.text.SimpleDateFormat df= new java.text.SimpleDateFormat();
        System.out.println("No pattern format :"+df.format(date));
        df.applyPattern("dd/mm/yyyy");
        System.out.println("dd/mm/yyyy format :"+df.format(date));
        df.applyPattern("dd/mm/yyyy HH:mm:ss");
        System.out.println("dd/mm/yyyy HH:mm:ss format :"+df.format(date));


Output for Java SimpleDateFormat

No format :Thu Apr 05 16:29:18 ICT 2012
No pattern format :5/4/2555, 16:29 น.
dd/mm/yyyy format :05/29/2555
dd/mm/yyyy HH:mm:ss format :05/29/2555 16:29:18