取消GWT中的按键事件 [英] Cancel a Keypress Event in GWT

问题描述

我想取消一个长文本框的按键事件，以便用户新按下的字符不会输入到文本框中。

I want to cancel a keypress event for a long textbox so that the character newly pressed by the user is not entered in the textbox

longBox_1.addKeyPressHandler(new KeyPressHandler(){
    @Override
    public void onKeyPress(KeyPressEvent event) {
        String Valid="1234567890";
        if (!Valid.contains(String.valueOf(event.getCharCode()))) {
            // the code to cancel the event to be placed here
        }
    }
});

推荐答案

如果您的longBox_1是您班级的私人成员，或者是一个final var，取消事件的代码是：

If your longBox_1 is a private member of your class, or a final var, the code to cancel the event is :

longBox_1.cancelKey();

否则，您可以投射事件的来源，如果您确定它对应于TextBox：< /（）>

Otherwise you can cast the source of the event, if you are sure it correspond to the TextBox :

((TextBox)event.getSource()).cancelKey();

以下是cancelKey的文档：

Here is the doc for cancelKey :

如果一个键盘事件当前在这个文本框中处理
，调用这个
方法将会抑制它。这允许
监听器可以轻松地过滤键盘
输入

If a keyboard event is currently being handled on this text box, calling this method will suppress it. This allows listeners to easily filter keyboard input

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