Simple Sort for RMS

/*--------------------------------------------------
* SimpleSort.java
*
* No GUI interface, all output is to the console
*
* Example from the book:     Core J2ME Technology
* Copyright John W. Muchow   http://www.CoreJ2ME.com
* You may use/modify for any non-commercial purpose
*-------------------------------------------------*/
import java.io.*;
import javax.microedition.midlet.*;
import javax.microedition.rms.*;

public class SimpleSort extends MIDlet
{
  private RecordStore rs = null;
  static final String REC_STORE = "db_1";

  public SimpleSort()
  {
    openRecStore();   // Create the record store
    
    // Write a few records
    writeRecord("Sand Wedge");
    writeRecord("One Wood");
    writeRecord("Putter");    
    writeRecord("Five Iron");        

    // Read back with enumerator, sorting the results
    readRecords();
    
    closeRecStore();  // Close record store
    deleteRecStore(); // Remove the record store
  }

  public void destroyApp( boolean unconditional )
  {
  }

  public void startApp()
  {
    // There is no user interface, go ahead and shutdown
    destroyApp(false);
    notifyDestroyed();
  }

  public void pauseApp()
  {
  }

  public void openRecStore()
  {
    try
    {
      // The second parameter indicates that the record store
      // should be created if it does not exist
      rs = RecordStore.openRecordStore(REC_STORE, true );
    }
    catch (Exception e)
    {
      db(e.toString());
    }
  }    
  
  public void closeRecStore()
  {
    try
    {
      rs.closeRecordStore();
    }
    catch (Exception e)
    {
      db(e.toString());
    }
  }

  public void deleteRecStore()
  {
    if (RecordStore.listRecordStores() != null)
    {
      try
      {
        RecordStore.deleteRecordStore(REC_STORE);
      }
      catch (Exception e)
      {
        db(e.toString());
      }
    }      
  }

  public void writeRecord(String str)
  {
    byte[] rec = str.getBytes();

    try
    {
      rs.addRecord(rec, 0, rec.length);
    }
    catch (Exception e)
    {
      db(e.toString());
    }
  }

  public void readRecords()
  {
    try
    {
      if (rs.getNumRecords() > 0)
      {
        Comparator comp = new Comparator();
        
        RecordEnumeration re = rs.enumerateRecords(null, comp, false);
        while (re.hasNextElement())
        {
          // Calls String constructor that takes an array of bytes as input
          String str = new String(re.nextRecord());

          System.out.println(str);
          System.out.println("------------------------------");                        
    
        }
      }
    }
    catch (Exception e)
    {
      db(e.toString());
    }
  }

  /*--------------------------------------------------
  * Simple message to console for debug/errors
  * When used with Exceptions we should handle the 
  * error in a more appropriate manner.
  *-------------------------------------------------*/
  private void db(String str)
  {
    System.err.println("Msg: " + str);
  }
}


/*--------------------------------------------------
* Compares two records to determine sort order
*-------------------------------------------------*/
class Comparator implements RecordComparator
{
  public int compare(byte[] rec1, byte[] rec2)
  {
    String str1 = new String(rec1), str2 = new String(rec2);
    
    int result = str1.compareTo(str2);
    if (result == 0)
      return RecordComparator.EQUIVALENT;
    else if (result < 0)
      return RecordComparator.PRECEDES;
    else
      return RecordComparator.FOLLOWS;          
  }
}

Related examples in the same category

1.	A simple class that shows various functionality of RMS.
2.	Sort records that contain multiple Java data types. Sort using String type.
3.	Birthday Database
4.	J2ME Data Management: Record Management System
5.	Write Read Example
6.	My Record Listener
7.	Demonstrates simple record sorting and filtering
8.	Display a Form and TextField for searching records. Each record contains a String object.
9.	Search Streams
10.	Int Sort

Simple Sort for RMS : Sort Search « J2ME « Java

Related examples in the same category