Bidirectionally bind to property negation

问题

Given

DoubleProperty A;
DoubleProperty minusA;

is there a way to bind their negations bidirectionally to each other, so that A.get() == -minusA.get() at all times, and both can be set()?

回答1:

I tried but did´t find a way by using a bidirectional binding but maybe you could use an InvalidationListner on both?

Something like

A.addListener((Observable observable) -> {
        System.out.println("A is invalid");
        minusA.set(A.get() *-1);
    });

minusA.addListener((Observable observable) -> {
        System.out.println("minusA is invalid");
        A.set(minusA.get() * -1);
    });

then you could easily call the setter method of both DoubleProperties and the other value will change to the negativ value.

Hope that helps

来源：https://stackoverflow.com/questions/34439109/bidirectionally-bind-to-property-negation