Allow only integers in a Jtable column

Question

Below I have a model of Jtable. There is only one editable column for number (seconds). How to validate to accept only integers, and in case the user enters anything else except integer, return ZERO?

public class Tabela_Fluxograma extends AbstractTableModel {
private ArrayList linhas = null;
private String[] colunas = null;

public Tabela_Fluxograma (ArrayList lin, String[] col){
    setLinhas(lin);
    setColunas(col);    
}

public ArrayList getLinhas() {
    return linhas;
}

public void setLinhas(ArrayList dados) {
    this.linhas = dados;
}

public String[] getColunas() {
    return colunas;
}

public void setColunas(String[] nome) {
    this.colunas = nome;
}

public int getColumnCount(){
    return colunas.length;
}

public int getRowCount (){
    return linhas.size();
}

public String getColumnName (int numCol){
    return colunas[numCol];
}

public Object getValueAt (int numLin, int numCol){
    Object[] linha = (Object[])getLinhas().get(numLin);
    return linha[numCol];
}

@Override
public boolean isCellEditable(int row, int column) {
return column == 3;
}

@Override
public void setValueAt(Object aValue, int rowIndex, int columnIndex) {
    Object[] linha = (Object[]) getLinhas().get(rowIndex);
    linha[columnIndex] = aValue;
    //este método é quem notifica a mudança do model na tabela
    fireTableDataChanged();
}

Answer 1

The correct way to restrict this is through the method getColumnClass that your Tablemodel inherits from AbstractTableModel:

public Class<?> getColumnClass(int columnIndex) { 
    return columnIdex == 3 ? Integer.class : super.getColumnClass(columnIndex);
}

That way there will not allow to save any value that is not of the type Integer in this column it is necessary to either leave blank or fill in correctly to allow the completion of the cell edition in this column.

Just to illustrate what will happen, see the gif below:

Answer 2

Good morning. As commented Articuno, I had to change to not allow text or return zero, although it is very useful your suggestion. Thanks for the suggestions. Just to finish I’ll put the final chunk of the tablemodel. I pass the value to another method, validates and returns.

@Override
public void setValueAt(Object aValue, int rowIndex, int columnIndex) {
    Object[] linha = (Object[]) getLinhas().get(rowIndex);
    int valor = validateInt(aValue);
    linha[columnIndex] = valor;
    fireTableDataChanged();
}

private int validateInt(Object numberObj){
    try {
        int number = Integer.parseInt((String) numberObj);
        return number; 
    } catch (Exception e) {
        return 0;
}
}

Answer 3

Using cast of Int you can do this validation:

private int validateInt(float number){
if(number == (int)number)
   return number;
else
   return 0
}