Question

我的代码是：

private EventHandler<KeyEvent> fieldChangeListener(final Integer max_Lengh, final Boolean fullTrimming) {
    return new EventHandler<KeyEvent>() {
        @Override
        public void handle(KeyEvent event) {
            TextField field = (TextField) event.getSource();
            String text = field.getText();
            int lastCharIndex = 0;

            if (field.getText().length() > 0) {
                lastCharIndex = field.getText().length() - 1;
            }

            if (field.getText().length() >= max_Lengh) {
                System.out.println("Exit 1");
                event.consume();
            }

            if (fullTrimming) {
                if (event.getCharacter().matches("\\s")) {
                    System.out.println("Exit 2");
                    event.consume();
                }
            } else {
                if (field.getText().length() == 0 && event.getCharacter().matches("\\s")) {
                    System.out.println("Exit 3");
                    event.consume();
                } else if (field.getText().substring(lastCharIndex).equals(" ")
                        && event.getCharacter().matches("\\s")) {
                    System.out.println("Exit 4");
                    event.consume();
                }
            }
            Region icon = (Region) ((StackPane)field.getParent()).getChildren().get(1);
            text = text+event.getCharacter();
            System.out.println("Char: " + text);

即使在事件被消耗之后，代码仍继续执行。因此，我可以获得如下输出：

Exit 1
Exit 4
Char: jk i okkl

但是我想在EventHandler被触发后立即退出event.consumed()。我怎么能这样做？

Answer 1

只需添加一些return语句：

        if (field.getText().length() >= max_Lengh) {
            System.out.println("Exit 1");
            event.consume();
            return;
        }

        if (fullTrimming) {
            if (event.getCharacter().matches("\\s")) {
                System.out.println("Exit 2");
                event.consume();
                return;
            }
        } else {
            ...
        }
        ...

然后你可能想稍微重构一下这个方法。通常我们应该只针对一个return陈述。

更新

这是代码全部必要的return - s：

public void handle(KeyEvent event) {
            TextField field = (TextField) event.getSource();
            String text = field.getText();
            int lastCharIndex = 0;

            if (field.getText().length() > 0) {
                lastCharIndex = field.getText().length() - 1;
            }

            if (field.getText().length() >= max_Lengh) {
                System.out.println("Exit 1");
                event.consume();
                return;
            }

            if (fullTrimming) {
                if (event.getCharacter().matches("\\s")) {
                    System.out.println("Exit 2");
                    event.consume();
                    return;
                }
            } else {
                if (field.getText().length() == 0 && event.getCharacter().matches("\\s")) {
                    System.out.println("Exit 3");
                    event.consume();
                    return;
                } else if (field.getText().substring(lastCharIndex).equals(" ")
                        && event.getCharacter().matches("\\s")) {
                    System.out.println("Exit 4");
                    event.consume();
                    return;
            }
        }
        Region icon = (Region) ((StackPane)field.getParent()).getChildren().get(1);
        text = text+event.getCharacter();
        System.out.println("Char: " + text);

        return;
}

如何在event.consume（）之后退出EventHandler？

1 个答案:

更新