UrlyBird : ArrayList problem

[Anthony Erickson]

Hello Everyone. I've found this website to be incredible useful in getting through the assignment.
I'm currently a bit on a problem with ArrayLists (URLyBird List getRecord() ). Everytime I add a field[] array to the ArrayList, it overwrites all previously added field[] arrays.

ArrayList retVal = new ArrayList();
for (int j=0; j < recor; j++)
{
    byte flag=raf.readByte();
    for(int k=0; k < numFields; k++) {
         bytesInField[k] = new byte[fieldlength[k]]; 
         raf.read(bytesInField[k],0,bytesInField[k].length);
         fields[k] = new String(bytesInField[k]);
              
      
    }
retVal.add(j,fields);
}
for(int h = 0; h < recordCount; h++){
String[] rec = (String[])retVal.get(h);
for( int k = 0; k<columnNames.length; k++){
System.out.print(k +"::::" + rec[k]);
}
}
  

Any idea on how to get around this?

[Philippe Maquet]

Hi Anthony,
Welcome to this forum.
What you seem to overwrite is the String rec[] in this loop :

for(int h = 0; h < recordCount; h++) {
    String[] rec = (String[])retVal.get(h);
}

Cheers,
Phil.

[Anthony Erickson]

Thanks, Phillipe. I'll have to give that a shot. Looks like lack of Much appreciated

[Anthony Erickson]

Hmm....Just tested the code out. I'm still stumped.
The first get() correctly pulls out the key, value pair.
The second get(), which is outside of the loops, shows that ALL values are set to the last added value.
Any ideas?

for (int j=0; j < rowCount; j++) {
byte flag=db.readByte();
      
for(int k=0; k < numFields; k++) {
         bytesInField[k] = new byte[fieldlength[k]]; 
         db.read(bytesInField[k],0,bytesInField[k].length);
         fields[k] = new String(bytesInField[k]);
   
        }
 retVal.add(j,fields);
  String[] rec = (String[])retVal.get(j);
 for( int k = 0; k<columnNames.length; k++)
{
    System.out.println(j +"::::" + rec[k]);
 }
}
 
String[] rectest = (String[])retVal.get(2);
 for( int l = 0; l<columnNames.length; l++)
{
    System.out.println(retVal.size());
    System.out.println(2 +"::::" + rectest[l]);
 }
  

[Philippe Maquet]

Hi Anthony,

The first get() correctly pulls out the key, value pair.
The second get(), which is outside of the loops, shows that ALL values are set to the last added value.

Normal I think : I don't see that you create a *new* fields array at each step in the for loop on rowCount.
Regards,
Phil.

[Anthony Erickson]

Thanks Philippe! It works now. Looks like a Java 101 Error (:eek on my part.