Question

I have a textbox for taking Amount i.e $100.

My textboxes already have a $ sign in them:

<g:TextBox ui:field="fee">$</g:TextBox>

What i want is that a user can never delete/edit $ sign inside my textBox and can only enter amount after that $ sign,

Is this possible?

Answer 1

This should work using events

button.addKeyPressHandler(new KeyPressHandler() {
  public void onKeyPress(KeyPressEvent event) {
    TextBox b = (TextBox)event.getSource();
    if (!b.getValue().startsWith("$")) {
      b.setValue("$" + b.getValue());
    }
  }
});

Although a solution based on css should look and perform better:

Put a lavel with the $ symbol over the input box.

Label l = new Label("$");
TextBox b = new TextBox();
l.getElement().addClassName("dollarlabel");
b.getElement().addClassName("dollarinput");
RootPanel.get().add(b);
RootPanel.get().add(l);

and some css styling

.dollarlabel {
  position: relative;
  float: left;
}
.dollarinput {
  margin-left: -10px;
  padding-left: 10px;
}