Problem - How you can read primitive data types from a file?

Contents

1. 1 Program :
   1. 1.1 Step 1 - Coding
   2. 1.2 Step 2 - Deployment
   3. 1.3 Step 3 - Testing
   4. 1.4 Output

Solution : java.io.RandomAccessFile behaves like a large array of bytes stored in the file system. There is a kind of cursor, or index into the implied array, called the file pointer.

Prerequisite:- You must create Write Primitive File first to run this program.

Program :

Step 1 - Coding

Create a text file c:/sunilos/ReadPrimitiveFile.java and copy below contents.

import java.io.RandomAccessFile;

/**
 * A program to read primitive data types in a file.
 */ 

public class ReadPrimitiveFile {

    public static void main(String[] args) throws Exception {
        long dataPosition=0;
        long data = 0;
        RandomAccessFile raf = new RandomAccessFile("c:/sunilos/sunilosfile.dat","r");
       
        dataPosition = raf.readLong();
       
        System.out.println("dataPosition : " +dataPosition);
       
        raf.seek(dataPosition);
        data = raf.readInt();
        raf.close();
        System.out.println("The dat is : " +data);
       
    }

}

Step 2 - Deployment

1. Create a folder 'c:\sunilos'. 
2. Create or copy ReadPrimitiveFile.java into 'c:\sunilos' folder.
3. Open your command prompt and go to  'c:\sunilos'
   
4. Compile ReadPrimitiveFile.java with help of 
• javac ReadPrimitiveFile.java command. Command will create ReadPrimitiveFile.class file in the same folder.
  
5. Congratulations!! your Java program is ready to serve.

Step 3 - Testing

1. Make sure you are on Command Prompt under c:\sunilos directory
   
2. Now start your java program from command prompt with help of 
• java ReadPrimitiveFile command.

Output

dataPosition : 32
The dat is : 1114399080

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