Change value of widget inside GWT flex table when other widget's value changes? - gwt

Question

Ok, so I have a pretty specific and to me quite complicated issue, as I'm a GWT newbie.
I have a GWT flex table, which I use to dynamically add rows, whose cells contain GWT widgets. The row number changes, but the number of columns in static, always 6. Each row contains a cell with a remove button and five cells each with their own textbox.
What I need to do is somehow code a kind of relationship between the textbox in cell 6 of one row and the textbox in cell 5 in the next row (and vice versa).
To illustrate: when something changes in the textbox at [1,6] the content of textbox at [2,5] needs to be overwritten with the same value. If the textbox at [2,5] changes the textbox at [1,6] needs to change as well. I cannot use a button to commit the changes, it needs to happen via onValueChange or Blur or something similar, which doesn't require the user to perform a specific action.
My problem stems mostly from trying to figure out how to address specific cells in the flex table and their content. For the remove button the solution was easy enough with a click event handler, but for this issue I just can't seem to be able to come up with a solution.
Sadly I also cannot provide any of the code which I have up until now, since it's a business secret. I can only give a broad description of the problem like the one above.
EDIT:
Actually, it's probably more a problem of not having much code in terms of this specific problem.
What I have is a flex table, which has initially only the header row. Upon clicking a button below this table the addNewField() method is called, which just contains the creation, setting of default values and adding of the text fields into a new row.
addNewField() {
int rows = flextable.getRowCount();
Button removeBtn = new Button("x");
removeBtn.getElement().setId(Integer.toString(rows));
//then the button's event handler
TextBox name = new TextBox();
name.setText("something");
flextable.setWidget(rows, 0, "name");
//repeat 4 more times with incrementing columns for the other widgets
}
This way I add entire rows of editable TextBoxes. What I need is a way to influence the values of the 6th column TextBox of a chosen row and the 5th column TextBox of chosen row + 1.
EDIT2: I've tried the dirty option just to see how it would go and somehow the compare inside the if breaks the app. The compiler detects a nullpointerexception and I can't even debug it with breakpoints because it fails to compile and won't start. I can't figure out why though. I threw the code directly into the event for testing purposes, so pardon the ugliness.
TextBox bis = new TextBox();
bis.setText(rows + ":10:00");
subs.setWidget(rows, 5, bis);
bis.addValueChangeHandler(new ValueChangeHandler<String>()
{
#Override
public void onValueChange(ValueChangeEvent<String> event)
{
allRows: for (int i = 0; i < subs.getRowCount(); i++)
{
for (int j = 0; j < subs.getCellCount(i); j++)
{
if ( subs.getWidget(i, j) == bis )
{
TextBox widgetAtColumnSix = ((TextBox) subs.getWidget(i, 5));
String text = widgetAtColumnSix.getText();
TextBox widgetAtColumnFiveRowPlusOne = ((TextBox) subs.getWidget(i + 1, 4));
widgetAtColumnFiveRowPlusOne.setText(text);
break allRows;
}
}
}
}
});

Answer 1

EDIT: Since you edited your question and you dont want to use EventBus you could iterate over your FlexTable and set your TextBox value depending on your current rowIndex and cellIndex... Its not nice but it should work:
public class CellWidget extends Composite {
private TextBox nameBox;
public CellWidget() {
FlowPanel flowPanel = new FlowPanel();
Button deleteButton = new Button("x");
nameBox = new TextBox();
nameBox.addValueChangeHandler(new ValueChangeHandler<String>() {
#Override
public void onValueChange(ValueChangeEvent<String> event) {
notifiyTextBox(CellWidget.this, event.getValue());
}
});
flowPanel.add(nameBox);
flowPanel.add(deleteButton);
initWidget(flowPanel);
}
public void setText(String text) {
nameBox.setText(text);
}
}
public void notifiyTextBox(CellWidget source, String string) {
rows: for (int i = 0; i < flextable.getRowCount(); i++) {
columns: for (int j = 0; j < flextable.getCellCount(i); j++) {
if (flextable.getWidget(i, j) == source) {
CellWidget widgetAtColumnSix = ((CellWidget) flextable.getWidget(i, 5));
widgetAtColumnSix.setText(string);
CellWidget widgetAtColumnFiveRowPlusOne = ((CellWidget) flextable.getWidget(i + 1, 4));
widgetAtColumnFiveRowPlusOne.setText(string);
break rows;
}
}
}
}
I still would recommend using an eventbus. To make it even more convenient there is the GWT Event Binder lib, which makes using events a breeze.
So when you change a value in your textbox[2,5] it also fires your CustomEvent. All Widgets, that need to change their textbox value just need to catch...