Heuristic exceptions

Heuristic exceptions are inconsistent exceptions . These exceptions does not come all the time and May occur suddenly due to some unavoidable condition 







For example You are calling a service to do some transaction on database and data-source configuration is missing . This happened because last time server got restarted Data-source configuration is removed . So this can be restored by setting the configuration right. 

For example in distributed system multiple parties taking part in a two phase commit transaction are waiting for transaction manager to get information If all of them should commit their individual transaction or not. Transaction manager took lot of time to response and Participant committed their individual transaction even before that . There could come a situation where some participants commit their transaction while others don't and they rollback it if transaction manager sends information to rollback. Thus in distributed system data becomes highly inconsistent .
You put some message in JMS queue But all of a sudden Queue connection breaks and you fail you get any proper response .

Such kind of strange and inconsistent exception falls under heuristic exceptions.

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Creating a zip file in java

Creating a zip file in java 




Converting a String into a test file and putting that in zip file 

1. Here I am creating File.zip file at location D:/file.zip
2. Here two text files are using by reading an existing txt file
3. One Pdf file is created by reading an existing file
4. One txt file is created from a String 
5. All are zipped together and are put in zip file 

import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;


public class Zipper {
    
    public static void main( String[] args )
    {
      byte[] buffer = new byte[1024];

      try{

        FileOutputStream fos = new FileOutputStream("D:\\File.zip");
        ZipOutputStream zos = new ZipOutputStream(fos);
        ZipEntry ze= new ZipEntry("spy.txt");
        zos.putNextEntry(ze);
        FileInputStream in = new FileInputStream("D:\\spy.txt");

        int len;
        while ((len = in.read(buffer)) > 0) {
          zos.write(buffer, 0, len);
        }

        in.close();
        
        ZipEntry ze1= new ZipEntry("spy1.txt");
        zos.putNextEntry(ze1);
        FileInputStream in1 = new FileInputStream("D:\\spy.txt");

        int len1;
        while ((len1 = in1.read(buffer)) > 0) {
          zos.write(buffer, 0, len1);
        }

        in1.close();
        
        ZipEntry ze2= new ZipEntry("Promote PDF.pdf");
        zos.putNextEntry(ze2);
        FileInputStream in2 = new FileInputStream("C:/Users/mkum63/Desktop/Promote PDF.pdf");

        int len2;
        while ((len2 = in2.read(buffer)) > 0) {
          zos.write(buffer, 0, len2);
        }

        in.close();
        
        
        ZipEntry ze4= new ZipEntry("spy4.txt");
        zos.putNextEntry(ze4);
        StringBuilder sb=new StringBuilder();
        sb.append("dfdgfdgf");
        sb.append("\n");
        sb.append("dsfsdfs");
        sb.append("/n");
        sb.append("dsfsfsdfdffdf");

        InputStream  in4 = new ByteArrayInputStream(sb.toString().getBytes());
                
        int len4;
        while ((len4 = in4.read(buffer))>0) {
          zos.write(buffer, 0, len4);
        }
          
        in4.close();
        
        zos.closeEntry();

        zos.close();

        System.out.println("Done");

      }catch(IOException ex){
         ex.printStackTrace();
      }
    }
}