Functionality to dynamically sort tableview columns

Question

Has anybody successfully tried sorting columns of a tableview component by clicking on its header? I need to sort a column containing dates in mm/dd/yyyy format. Please share your hints or code. BR, Maulin

Answer 1

Hi,
Here is the code, no support included :-):
import java.util.Collections;
import java.util.Comparator;
import java.util.Vector;
import com.sapportals.htmlb.table.DefaultTableViewModel;
public class SortTableModel extends DefaultTableViewModel implements Comparator {
     protected int currCol;
     protected Vector ascendCol; // this vector stores the state (ascending or descending) of each column
     protected Integer one = new Integer(1);
     protected Integer minusOne = new Integer(-1);
     public SortTableModel() {
          super();
          ascendCol = new Vector();
     public SortTableModel(Vector vec) {
          super(vec);
          ascendCol = new Vector();
     public SortTableModel(Vector vec, Vector vec2, int numberOfColumns) {
          super(vec, vec2);
          ascendCol = new Vector();
          setSortOrder(numberOfColumns);
This method is the implementation of the Comparator interface.
It is used for sorting the rows
     public int compare(Object v1, Object v2) {
          // the comparison is between 2 vectors, each representing a row
          // the comparison is done between 2 objects from the different rows that are in the column that is being sorted
          int ascending = ((Integer)ascendCol.get(currCol)).intValue();
          if (v1 == null && v2 == null) {
               return 0;
          } else if (v2 == null) { // Define null less than everything.
               return 1 * ascending;
          } else if (v1 == null) {
               return -1 * ascending;
          Object o1 = ((Vector)v1).get(currCol);
          Object o2 = ((Vector)v2).get(currCol);
          // If both values are null, return 0.
          if (o1 == null && o2 == null) {
               return 0;
          } else if (o2 == null) { // Define null less than everything.
               return 1 * ascending;
          } else if (o1 == null) {
               return -1 * ascending;
          if (o1 instanceof Number && o2 instanceof Number) {
               Number n1 = (Number)o1;
               double d1 = n1.doubleValue();
               Number n2 = (Number)o2;
               double d2 = n2.doubleValue();
               if (d1 == d2) {
                    return 0;
               } else if (d1 > d2) {
                    return 1 * ascending;
               } else {
                    return -1 * ascending;
          } else if (o1 instanceof Boolean && o2 instanceof Boolean) {
               Boolean bool1 = (Boolean)o1;
               boolean b1 = bool1.booleanValue();
               Boolean bool2 = (Boolean)o2;
               boolean b2 = bool2.booleanValue();
               if (b1 == b2) {
                    return 0;
               } else if (b1) {
                    return 1 * ascending;
               } else {
                    return -1 * ascending;
          } else {
               // default case
               if (o1 instanceof Comparable && o2 instanceof Comparable) {
                    Comparable c1 = (Comparable)o1;
                    Comparable c2 = (Comparable)o2; // superflous cast, no need for it!
                    try {
                         return c1.compareTo(c2) * ascending;
                    } catch (ClassCastException cce) {
                         // forget it... we'll deal with them like 2 normal objects below.
               String s1 = o1.toString();
               String s2 = o2.toString();
               return s1.compareTo(s2) * ascending;
This method sorts the rows using Java's Collections class.
After sorting, it changes the state of the column -
if the column was ascending, its new state is descending, and vice versa.
     public void sort() {
          Collections.sort(dataVector, this);
          Integer val = (Integer)ascendCol.get(currCol);
          ascendCol.remove(currCol);
          if (val.equals(one)) // change the state of the column
               ascendCol.add(currCol, minusOne);
          else
               ascendCol.add(currCol, one);
     public void sortByColumn(int column) {
          this.currCol = column;
          sort();
     public void setSortOrder(int numberOfColumns) {
          for (int i = 0; i < numberOfColumns; i++) {
               ascendCol.add(one);