JavaFX:错误记录 ChangeListener

Question

我想概括以下模式:

setChangeListener = c -> {
    try {
    // do something dangerous
    } catch (final IOException e) {
    logger.error(e.getLocalizedMessage(), e);
    }
};

我想这样使用它:

errorLoggingSetChangeListener = c -> {
    // do something dangerous
};

我在想这个:

public class ErrorLoggingSetChangeListener<T> implements SetChangeListener<T> {
    private static final Logger logger = Logger.getLogger(ErrorLoggingSetChangeListener.class);
    private final SetChangeListener<T> delegate;

    @Override
    public void onChanged(final SetChangeListener.Change<? extends T> change) {
    try {
        delegate.onChanged(change);
    } catch (final Exception e) {
        if (logger.isEnabledFor(Level.ERROR)) {
        logger.error(e.getLocalizedMessage(), e);
        }
    }
    }

    public ErrorLoggingSetChangeListener(final SetChangeListener<T> delegate) {
    super();
    this.delegate = delegate;
    }
}

但这不可能，因为 ErrorLoggingSetChangeListener 不是功能接口(interface)。

有机会将此类转换为函数式接口(interface)吗？

这不会编译:

public interface ErrorLoggingSetChangeListener<T> extends SetChangeListener<T> {

    static final Logger logger = Logger.getLogger(ErrorLoggingSetChangeListener.class);

    @Override
    default void onChanged(final SetChangeListener.Change<? extends T> change) {
    try {
        SetChangeListener.super.onChanged(change);
    } catch (final Exception e) {
        if (logger.isEnabledFor(Level.ERROR)) {
        logger.error(e.getLocalizedMessage(), e);
        }
    }
    }
}

这也无法编译:

errorLoggingSetChangeListener = new ErrorLoggingSetChangeListener<>(c -> {
      throw new IOException();
    });

错误信息是

Unhandled exception [..]

.

Answer 1

这与 @JonnyAW 的解决方案类似，但将两个类组合到一个接口(interface)中:

import javafx.collections.SetChangeListener;

@FunctionalInterface
public interface ErrorLoggingSetChangeListener<E> extends SetChangeListener<E> {


    public void delegate(Change<? extends E> change) throws Exception ;

    @Override
    public default void onChanged(Change<? extends E> change) {
        try {
            delegate(change);
        } catch (Exception exc) {
            // just do a System.out.println here to demo we reach this block:
            System.out.println("Custom error handling...");
            exc.printStackTrace();
        }
    }
}

这是使用此功能的演示:

import javafx.collections.FXCollections;
import javafx.collections.ObservableSet;

public class Test {

    public static void main(String[] args) {
        ObservableSet<String> set = FXCollections.observableSet();
        ErrorLoggingSetChangeListener<String> listener = c -> {
            if (c.wasAdded()) {
                int i = Integer.parseInt(c.getElementAdded());
                System.out.println("Value added: "+i);
            }
        };
        set.addListener(listener);

        set.add("42");
        set.add("What do you get when you multiply 6 by 9?");
    }

}

生成预期的输出:

Value added: 42
Custom error handling...
java.lang.NumberFormatException: For input string: "What do you get when you multiply 6 by 9?"
    at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
    at java.lang.Integer.parseInt(Integer.java:580)
    at java.lang.Integer.parseInt(Integer.java:615)
    at Test.lambda$0(Test.java:10)
    at ErrorLoggingSetChangeListener.onChanged(ErrorLoggingSetChangeListener.java:12)
    at com.sun.javafx.collections.SetListenerHelper$SingleChange.fireValueChangedEvent(SetListenerHelper.java:163)
    at com.sun.javafx.collections.SetListenerHelper.fireValueChangedEvent(SetListenerHelper.java:72)
    at com.sun.javafx.collections.ObservableSetWrapper.callObservers(ObservableSetWrapper.java:128)
    at com.sun.javafx.collections.ObservableSetWrapper.add(ObservableSetWrapper.java:269)
    at Test.main(Test.java:17)