How do I restrict my EditText input to numerical (possibly decimal and signed) input?

There's no reason to use setRawInputType(), just use setInputType(). However, you have to combine the class and flags with the OR operator:

edit.setInputType(InputType.TYPE_CLASS_NUMBER | InputType.TYPE_NUMBER_FLAG_DECIMAL | InputType.TYPE_NUMBER_FLAG_SIGNED);

Try using TextView.setRawInputType() it corresponds to the android:inputType attribute.

Use this. Works fine

input.setInputType(InputType.TYPE_CLASS_NUMBER | InputType.TYPE_NUMBER_FLAG_DECIMAL | InputType.TYPE_NUMBER_FLAG_SIGNED);
input.setKeyListener(DigitsKeyListener.getInstance("0123456789"));

EDIT

kotlin version

fun EditText.onlyNumbers() {
    inputType = InputType.TYPE_CLASS_NUMBER or InputType.TYPE_NUMBER_FLAG_DECIMAL or
        InputType.TYPE_NUMBER_FLAG_SIGNED
    keyListener = DigitsKeyListener.getInstance("0123456789")
}