如何按JFace TableViewer的多列进行排序

Question

I'm trying to implement a tableviewer that can sort values depending on the order in which column header(s) are clicked by user. eg If there are three columns column1, column2, column3 and user has clicked the columns in the following order column3, column2, column1 then, rows first on the values of column 3 gets sorted, then column 2 and finally column1.

I have overided the compare method in the folowing way:

protected int doCompare(Viewer tableViewer, Object row1, Object row2) 
{
    SampleTableLabelProvider labelProvider = SampleTableLabelProvider ((TableViewer) tableViewer).getLabelProvider());
    boolean areBothRowsEqual = false;
    for(String orderedColumn : getOrderedList()) // getOrderedList() stores the column names in the order in which they are clicked by user
    {
        int orderedColumnIndex = // logic to get the index of orderedColumn in the tableViewer  ;
        if(compareStrings(labelProvider, row1, row2, orderedColumnIndex ) == 0)
        {
            areBothRowsEqual = true;
        }
        else
        {
            areBothRowsEqual = false;
            break;
        }   

    }
    if(areBothRowsEqual)
    {
        return compareStrings(labelProvider, row1, row2, columnIndex);
    }
    else
    {
        return 0;
    }
}   

This logic is not working and this is what is happening: For eg column3 is selected by the user and this column gets sorted. But next time when a another column say column2 is clicked the objects row1 and row2 from the TableViewer don't appear in the latest ordered format.

How do I achieve this?

Answer 1

The problem you are facing seems to be in properties of sorting algorithm. Stable algorithm will leave your date column1 sorted after you implement column2 sorting. You have to check whether you algorithm in the method getOrderedList() is stable .