Vitali,
GWT does not seem too excited about Matcher and bombs out completely.
I don't believe it's compatible client side, as it says
java.util.regex cannot be imported.
I've confirmed that Gears on Android does not support sentences with
another user.
I misspoke when I posted my code snippet, I was using replaceFirst. As
I stated before that Regexp ([?]) does not appear to match ? as
replaceFirst does not ever replace the ?. "\\?" does not seem to work
in replaceFirst either; however, "\\?" does work with .split.
So, I think the two solutions I've got so far are:
for ( int i = 0; ( statement.indexOf( "?" ) > 0 ); i++ )
{
int index = statement.indexOf( '?' );
String firstPart = statement.substring( 0, index );
String secondPart = statement.substring( index + 1 );
StringBuilder sb = new StringBuilder();
sb.append( firstPart ).append( "\"" ).append( params[ i ] ).append
( "\"" ).append( secondPart );
statement = sb.toString();
}
return statement;
OR
StringBuilder sb = new StringBuilder();
String[] splits = statement.split( "\\?" );
int j = 0;
sb.append( splits[ 0 ] );
for( int i = 1; i < splits.length; i++ )
{
sb.append( '"' ).append( params[ j ] ).append( '"' ).append( splits
[ i ] );
j++;
}
if ( j < params.length )
{
sb.append( '"' ).append( params[ j ] ).append( '"' );
j++;
}
if ( j != params.length )
{
throw new IndexOutOfBoundsException();
}
return sb.toString();
With neither method being particularly quick. I suspect the second
method will give better general performance.
E
On May 8, 10:46 am, Vitali Lovich <[email protected]> wrote:
> Have you read the Javadoc? replace replaces string literals. You need
> myString.replaceAll("[?]", newString); or myString.replace("?", newString).
> In any case, it's not what you want since it replaces *all* instances of ?
> with the same string. Try this:
>
> Matcher m = Pattern.compile("[?]").matcher(myString);
> int i = 0;
> while (!m.hitEnd())
> {
> m.replaceFirst('"' + params[i++] + '"');
>
> }
>
> You could use String.replaceFirst, but this should be better performing.
> Otherwise, you have to do:
>
> String newString;
> int i = 0;
> while (!(newString = myString.replaceFirst("[?]", '"' + params[i++] +
> '"')).equals(myString))
> {
> myString = newString;
>
> }
>
> but that might be slower than even the split method I gave earlier.
>
> And if this code is really slow, there's a faster JSNI way because
> Javascript has a faster way for literal regexps & I don't believe the
> compiler makes that optimization yet.
>
> In any case, I would really recommend trying to figure out why your SQL
> stuff doesn't work first, because that is the core of the problem. All of
> this stuff is just hacky workarounds.
>
> You really should write the equivalent little javascript snippet & see if
> that works. If it doesn't, then post to the android list because it's a
> problem with your code.
>
> On Fri, May 8, 2009 at 8:33 AM, Evan Ruff <[email protected]> wrote:
>
> > I was going with the ol:
>
> > myString.replace( "[?]", newString );
>
> > but that would not find the ?, so I went with a "\\?", also
> > unsuccessfully.
>
> > E
>
> > On May 8, 12:00 am, Vitali Lovich <[email protected]> wrote:
> > > What is the exact Java code snippet that you are using?
>
> > > On Thu, May 7, 2009 at 10:10 PM, Evan Ruff <[email protected]> wrote:
>
> > > > Vitali,
>
> > > > I was just trying to match '?' in the SQL statement, such as:
>
> > > > INSERT into users ( name, city ) VALUES( ?, ? )
>
> > > > so I can mash up my own prepare SQL statement.
>
> > > > Also, I can run the test on the android phone to see if that might be
> > > > the problem.
>
> > > > E
>
> > > > On May 7, 4:36 pm, Vitali Lovich <[email protected]> wrote:
> > > > > What's the code for the regexp that you are trying & what is the
> > source
> > > > > string that you are matching against.
>
> > > > > On Thu, May 7, 2009 at 3:24 PM, Evan Ruff <[email protected]>
> > wrote:
>
> > > > > > Vitali,
>
> > > > > > Thanks for your response!
>
> > > > > > That RegExp for the ? was giving me trouble, as it wouldn't match.
>
> > > > > > I also tried [\\?] without success as well. Any idea on how to find
> > > > > > that guy?
>
> > > > > > Thanks,
>
> > > > > > E
>
> > > > > > On May 7, 2:59 pm, Vitali Lovich <[email protected]> wrote:
> > > > > > > Javascript & Java have different regular expressions, so if you
> > are
> > > > > > running
> > > > > > > your stuff on desktop browsers in Hosted Mode but compiled mode
> > in
> > > > > > Android,
> > > > > > > then you might be running into that problem.
>
> > > > > > > A performance improvement should be:
>
> > > > > > > String statement = new String( sqlStatement );
> > > > > > > StringBuffer sb = new StringBuffer(statement.length());
> > > > > > > int index;
> > > > > > > int previous = 0;
> > > > > > > int i = 0;
>
> > > > > > > while ((index = statement.indexOf('?')) != -1)
> > > > > > > {
> > > > > > > String firstPart = statement.substring( previous, index );
> > > > > > > sb.append
> > (firstPart).append('"').append(params[i++]).append('"');
> > > > > > > previous = index + 1;
>
> > > > > > > }
>
> > > > > > > return sb.toString();
>
> > > > > > > or try
>
> > > > > > > String statement = new String( sqlStatement );
> > > > > > > String [] parts = statement.split("[?]");
> > > > > > > StringBuffer sb = new StringBuffer(statement.length +
> > parts.length *
> > > > > > > AVERAGE_PARAM_LENGTH);
>
> > > > > > > for (int i = 0; i < parts.length; i++)
> > > > > > > {
> > > > > > > sb.append(parts[i]).append('"').append(params[i]).append('"')
>
> > > > > > > }
>
> > > > > > > AVERAGE_PARAM_LENGTH can be anything, but you want the resultant
> > > > > > expression
> > > > > > > to be as close as possible to the actual final length as
> > possible,
> > > > > > without
> > > > > > > going under (assuming this portion of code is your hotpath -
> > > > otherwise,
> > > > > > you
> > > > > > > won't notice the difference).
>
> > > > > > > On Thu, May 7, 2009 at 2:12 PM, Evan Ruff <[email protected]>
> > > > wrote:
>
> > > > > > > > Ok so something really fishy is going on with the Gears API.
>
> > > > > > > > I created my own "prepareSQLStatement" that converts the SQL
> > Call
> > > > and
> > > > > > > > parameter list into a string.
>
> > > > > > > > private String prepareSQLStatement( String sqlStatement,
> > > > > > String[]
> > > > > > > > params ) throws DatabaseException
> > > > > > > > {
> > > > > > > > try
> > > > > > > > {
> > > > > > > > String statement = new String(
> > sqlStatement
> > > > );
>
> > > > > > > > for ( int i = 0; ( statement.indexOf(
> > "?" )
> > > > > 0
> > > > > > );
> > > > > > > > i++ )
> > > > > > > > {
> > > > > > > > int index = statement.indexOf(
> > '?'
> > > > );
> > > > > > > > String firstPart =
> > > > statement.substring(
> > > > > > 0,
> > > > > > > > index );
> > > > > > > > String secondPart =
> > > > statement.substring(
> > > > > > > > index + 1 );
>
> > > > > > > > StringBuffer sb = new
> > > > StringBuffer();
> > > > > > > > sb.append( firstPart ).append(
> > "\""
> > > > > > > > ).append( params[ i ] ).append
> > > > > > > > ( "\"" ).append( secondPart );
> > > > > > > > statement = sb.toString();
> > > > > > > > }
>
> > > > > > > > return statement;
> > > > > > > > }
> > > > > > > > catch ( IndexOutOfBoundsException indexOut )
> > > > > > > > {
> > > > > > > > throw new DatabaseException( "Index out
> > of
> > > > > > bounds.
> > > > > > > > SQL Parameter
> > > > > > > > Error" );
> > > > > > > > }
> > > > > > > > }
>
> > > > > > > > When I use this method to prepare the statement before hitting
> > > > > > > > db.execute, all of my sql statements work as expected.
>
> > > > > > > > Could Android implement it's string manipulation stack slightly
> > > > > > > > differently than all the other platforms? I've got a sneaky
> > > > suspecion
> > > > > > > > that the RegExp that's used to parse the '?' in the SQL
> > commands
> > > > might
> > > > > > > > be failing?
>
> > > > > > > > Furthermore, can anyone give me an ideas as how to improve the
> > > > > > > > performance of the above method? It creates a noticable delay.
> > Did
> > > > I
> > > > > > > > read somewhere that GWT has a slow string manipulation engine?
>
> > > > > > > > E
>
> > > > > > > > On May 6, 2:07 pm, Evan Ruff <[email protected]> wrote:
> > > > > > > > > Hey Eric,
>
> > > > > > > > > I'm pretty much terrified of Javascript.
>
> > > > > > > > > I'm a little hesitant to make any determination whatsoever as
> > to
> > > > the
> > > > > > > > > cause of the problem. When I run the GWT Gears Sample
> > > > DatabaseDemo
> > > > > > > > > project, it works as expected. I can even replace all of the
> > DB
> > > > > > > > > specifics with the internals of my tables/queries and it
> > seems to
> > > > > > > > > work! It's just so freakin' frustrating.
>
> > > > > > > > > RememberTheMilk and the mobile GMail seem to make use of
> > Gears on
> > > > > > > > > Android without issue, so I really don't know where to go
> > from
> > > > here.
> > > > > > > > > Any other suggestions?
>
> > > > > > > > > Here's the replaced DatabaseDemo code, fwiw:
>
> > > > > > > > > public class Gears implements EntryPoint
> > > > > > > > > {
> > > > > > > > > private static final int NUM_SAVED_ROWS = 3;
> > > > > > > > > private static final int NUM_DATA_TABLE_COLUMNS = 3;
>
> > > > > > > > > private final Button addButton = new Button( "Add" );
> > > > > > > > > private final Button clearButton = new Button( "Clear
> > > > > > Database"
> > > > > > > > );
> > > > > > > > > private Database db;
> > > > > > > > > private final TextBox input = new TextBox();
> > > > > > > > > private final FlexTable dataTable = new FlexTable();
>
> > > > > > > > > public void onModuleLoad()
> > > > > > > > > {
> > > > > > > > > VerticalPanel outerPanel = new
> > VerticalPanel();
> > > > > > > > > outerPanel.setSpacing( 10 );
>
> > outerPanel.getElement().getStyle().setPropertyPx(
> > > > > > > > "margin", 15 );
>
> > > > > > > > > HorizontalPanel textAndButtonsPanel = new
> > > > > > > > HorizontalPanel();
> > > > > > > > > textAndButtonsPanel.add( new Label( "Enter a
> > > > Phrase:
> > > > > > " )
> > > > > > > > );
> > > > > > > > > textAndButtonsPanel.add( input );
> > > > > > > > > textAndButtonsPanel.add( addButton );
> > > > > > > > > textAndButtonsPanel.add( clearButton );
> > > > > > > > > outerPanel.add( textAndButtonsPanel );
> > > > > > > > > outerPanel.add( new Label( "Last 3 Entries:"
> > ) );
> > > > > > > > > outerPanel.add( dataTable );
>
> > > > > > > > > for ( int i = 0; i <= NUM_SAVED_ROWS; ++i )
> > > > > > > > > {
> > > > > > > > > dataTable.insertRow( i );
> > > > > > > > > for ( int j = 0; j <
> > > > NUM_DATA_TABLE_COLUMNS;
> > > > > > j++
> > > > > > > > )
> > > > > > > > > {
>
> ...
>
> read more »
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