Column in gwt celltable doesn't sort - sorting

Question

I want to add sorting for column in celltable with help of ListHandler. But it doesn't sort. I don't understand why it doesn't work. My code is based on GWT tutorial.
Please suggest me something.
Contract.java
public class Contract implements Serializable {
private int contId;
private String contOrgName;
//getters and setters...
}
Main.java
TextColumn<Contract> orgNameColumn = new TextColumn<Contract>() {
#Override
public String getValue(Contract contract) {
return contract.getcontOrgName();
}};
orgNameColumn.setSortable(true);
CellTable<Contract> tableContract = new CellTable<Contract>();
tableContract.addColumn(orgNameColumn, "OrgName");
ListDataProvider<Contract> contractDataProvider = new ListDataProvider<Contract>();
contractDataProvider.addDataDisplay(tableContract);
GetContractsServiceAsync getContractsService = GWT.create(GetContractsService.class);
getContractsService.getContracts(new AsyncCallback<List<Contract>>() {
public void onFailure(Throwable caught) {
// Show the RPC error message to the user
}
public void onSuccess(List<Contract> result) {
contractDataProvider.getList().clear();
contractDataProvider.getList().addAll(result);
ListHandler<Contract> columnSortHandler = new ListHandler<Contract>(result);
columnSortHandler.setComparator(orgNameColumn, new Comparator<Contract>() {
public int compare(Contract o1, Contract o2) {
if (o1 == o2) {
return 0;
}
if (o1 != null) {
return (o2 != null) ? o1.getcontOrgName().compareTo(o2.getcontOrgName()) : 1;
}
return -1;
}
});
tableContract.addColumnSortHandler(columnSortHandler);
table.getColumnSortList().push(orgNameColumn);
}
});

Answer 1

Hey I was also facing the same issue a long back..Then I got to know that the object reference id is different than the one I have added into table. Once i got the reason it was very easy to find the solution.
Also please register your ListHandler before adding column to CellTable.
Note the edit for your comment :
There is nothing wrong with the comparator. The problem is still same. It reflects the wrong the object in comparator compared to in CellTable.
Please try replace the code as below :
contractDataProvider.getList().addAll(result);
ListHandler<Contract> columnSortHandler = new ListHandler<Contract>(contractDataProvider.getList());

Answer 2

Try to move the creation of your columnSortHandler out of the onSuccess Method. Place it right after you created your column.
At the moment you are adding the results before you add the columnSortHandler. I think that is the wrong order.

Answer 3

i my case, i did my sorting like this:
private void sortColumn( List<CModel> list ) {
int count = listOfColumns.size(); //upon adding the columns, i have created a list that will hold all the columns
if ( list.size() <= 0 ) {
for ( int i = 0; i < count; i++ ) {
listOfColumns.get(i).setSortable( false );
}
} else {
for ( int i = 0; i < count; i++ ) {
sort( i );
dg.redrawHeaders();
}
}
}
private void sort(int i) {
String[] listColHead = { /** list of column headers */ };
Column<CModel,?> column = listCheckoutColumns.get( i );
final String valueToCompare = listColHead[i];
final ListDataProvider<CModel> dataProvider = new ListDataProvider<CModel>();
// Connect the table to the data provider
dataProvider.addDataDisplay( dg );
// Add the data to the data provider, which automatically pushes it to the widget
List<CModel> list = dataProvider.getList();
for ( CModel product : listCheckout ) {
list.add( product );
}
column.setSortable( true );
// Add a ColumnSortEvent.ListHandler to connect sorting to the List
ListHandler<CModel> columnSortHandler = new ListHandler<CModel>( list );
columnSortHandler.setComparator( column, new Comparator<CModel>() {
public int compare( CModel p1, CModel p2 ) {
if ( p1 == p2 ) {
return 0;
}
// Compare the columns.
if ( p1 != null ) {
if ( valueToCompare.equals( "code" ) ) {
return ( p2 != null ) ? p1.getFproductid().compareTo( p2.getFproductid() ) : 1;
}
else if ( valueToCompare.equals( "desc" ) ) {
return ( p2 != null ) ? p1.getFproduct_name().compareTo( p2.getFproduct_name() ) : 1;
}
else if ( valueToCompare.equals( "type" ) ) {
return ( p2 != null ) ?
uec.computeTypeLabel( p1 ).compareTo( uec.computeTypeLabel( p2 ) ) : 1;
}
else if ( valueToCompare.equals( "maxex" ) ) {
return ( p2 != null ) ? uec.exQtyLabel( p1 ).compareTo( uec.exQtyLabel( p2 ) ) : 1;
}
else if ( valueToCompare.equals( "unit" ) ) {
return ( p2 != null ) ? p1.getFuom().compareTo( p2.getFuom() ) : 1;
}
else if ( valueToCompare.equals( "status" ) ) {
return ( p2 != null ) ? uec.qtyLabel( p1 ).compareTo( uec.qtyLabel( p2 ) ) : 1;
}
else if ( valueToCompare.equals( "qty" ) ) {
return ( p2 != null ) ? Double.compare( p1.getFqty(), p2.getFqty() ) : 1;
}
else if ( valueToCompare.equals( "price" ) ) {
return ( p2 != null ) ? uec.extPriceLabel( p1 ).compareTo( uec.extPriceLabel( p2 ) ) : 1;
}
else if ( valueToCompare.equals( "total" ) ) {
return ( p2 != null ) ? Double.compare( p1.getFtotal_line(), p2.getFtotal_line() ) : 1;
}
}
return -1;
}
});
dg.addColumnSortHandler( columnSortHandler );
dg.getColumnSortList().push( column );
}
everytime, i'll set the data for my DataGrid list,
dgCheckout.redraw();
dgCheckout.setRowCount( lengthOfList, true );
dgCheckout.setRowData( 0, newList );
sortColumn( newList );