import com.google.gwt.event.dom.client.HasAllFocusHandlers; //导入依赖的package包/类
protected <H extends HasAllFocusHandlers & HasEnabled> void checkFocusAndBlurEvents(H widget) {
    // Check Focus
    final boolean[] isFocusFired = {false};
    widget.addFocusHandler(focusEvent -> isFocusFired[0] = true);
    fireFocusEvent(widget);

    // Check Blur
    final boolean[] isBlurFired = {false};
    widget.addBlurHandler(blurEvent -> isBlurFired[0] = true);
    fireBlurEvent(widget);

    assertEquals(widget.isEnabled(), isFocusFired[0]);
    assertEquals(widget.isEnabled(), isBlurFired[0]);
}
 

import com.google.gwt.event.dom.client.HasAllFocusHandlers; //导入依赖的package包/类
public HandlerRegistration addFocusHandler(FocusHandler handler) {
	if (uiObject instanceof HasAllFocusHandlers) {
		return ((HasAllFocusHandlers)uiObject).addFocusHandler(handler);
	}
	return null;
}
 

import com.google.gwt.event.dom.client.HasAllFocusHandlers; //导入依赖的package包/类
public HandlerRegistration addBlurHandler(BlurHandler handler) {
	if (uiObject instanceof HasAllFocusHandlers) {
		return ((HasAllFocusHandlers)uiObject).addBlurHandler(handler);
	}
	return null;
}
 

import com.google.gwt.event.dom.client.HasAllFocusHandlers; //导入依赖的package包/类
public HandlerRegistration addFocusHandler(FocusHandler handler) {
	if (textbox instanceof HasAllFocusHandlers){
		return ((HasAllFocusHandlers)textbox).addFocusHandler(handler);
	}
	return null;
}
 

import com.google.gwt.event.dom.client.HasAllFocusHandlers; //导入依赖的package包/类
public HandlerRegistration addBlurHandler(BlurHandler handler) {
	if (textbox instanceof HasAllFocusHandlers){
		return ((HasAllFocusHandlers)textbox).addBlurHandler(handler);
	}
	return null;
}