Question

我正在尝试将AtomicBoolean绑定到JCheckBox的“enabled”属性。由于AtomicBoolean不是布尔的替代品，我使用的是自定义转换器。但是，下面显示的转换器会导致ClassCastException。为什么呢？

org.jdesktop.beansbinding.Binding binding = org.jdesktop.beansbinding.Bindings.createAutoBinding(org.jdesktop.beansbinding.AutoBinding.UpdateStrategy.READ, isIdle, org.jdesktop.beansbinding.ObjectProperty.create(), cornerCb, org.jdesktop.beansbinding.BeanProperty.create("enabled"));
        binding.setConverter(new Converter<AtomicBoolean, Boolean>() {
            @Override
            public Boolean convertForward(AtomicBoolean value) {
                Boolean b = value.get();
                return b;
            }

            @Override
            public AtomicBoolean convertReverse(Boolean value) {
                return new AtomicBoolean(value);
            }
        });

产生的异常

java.lang.ClassCastException
        at java.lang.Class.cast(Class.java:2990)
        at org.jdesktop.beansbinding.Binding.convertForward(Binding.java:1312)
        at org.jdesktop.beansbinding.Binding.getSourceValueForTarget(Binding.java:844)
        at org.jdesktop.beansbinding.Binding.refreshUnmanaged(Binding.java:1222)
        at org.jdesktop.beansbinding.Binding.refresh(Binding.java:1207)
        at org.jdesktop.beansbinding.Binding.refreshAndNotify(Binding.java:1143)
        at org.jdesktop.beansbinding.AutoBinding.bindImpl(AutoBinding.java:197)
        at org.jdesktop.beansbinding.Binding.bindUnmanaged(Binding.java:959)
        at org.jdesktop.beansbinding.Binding.bind(Binding.java:944)
        at org.jdesktop.beansbinding.BindingGroup.bind(BindingGroup.java:143)

Answer 1

该异常不是来自您的代码。它发生在这里：

private final TV convertForward(SV value) {
    if (converter == null) {
        Class<?> targetType = noPrimitiveType(targetProperty.getWriteType(targetObject));
        return (TV)targetType.cast(Converter.defaultConvert(value, targetType));
    }

    return converter.convertForward(value);
}

有一些不同的maven工件在其中包含该类，并且在第1312行调用了Class.cast（）。使用它并不重要。您可能需要进行一些调试。在该行上放置一个断点，然后您可以跟踪回调并查看传递的值以及异常发生的原因。似乎您的转换器由于某种原因未被使用，这可能是问题所在。它可能试图将AtomicBoolean强制转换为Boolean。

Java数据绑定和自定义转换器

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