在SWT中验证文本并尝试清除它，但不起作用

Question

I am trying to verify a text in SWT to allow only binary numbers and it works, but my problem is that I have a button that I need to reset the field but it doesn't work.

Here is the code

DACMUX.addVerifyListener(new VerifyListener() {

            public void verifyText(VerifyEvent e) {
                e.doit = false;

                char myChar = e.character;
                if (myChar == '1' || myChar == '0' || myChar == '\b'){
                    e.doit = true;
                }
            }
        });

reset.addSelectionListener(new SelectionListener() {

            @Override
            public void widgetSelected(SelectionEvent e) {
            DACMUX.setText(""); 

            }

            @Override
            public void widgetDefaultSelected(SelectionEvent e) {
                // TODO Auto-generated method stub

            }
        });

Answer 1

Interesting case you got there. Took me a while to figure it out.

Right, so here goes: The VerifyListener is fired after you call setText("") . It checks your condition and it validates to false , so nothing changes.

To make it work, you need to add one additional OR case to your if , which checks if Event#text equals "" . This is the case when you call setText("") . It won't mess up you other logic.

So here is the working if :

if (myChar == '1' || myChar == '0' || myChar == '\b' || e.text.equals(""))
{
    e.doit = true;
}