java - 无法将组件添加到布局

Question

大家好，我遇到了一个奇怪的问题，但我确信我在做一些愚蠢的事情。在 Maven 项目中，我的 UI 类如下:

package my.vaadin.project.exceptionTest;
import javax.servlet.annotation.WebServlet;
import com.vaadin.annotations.Theme;
import com.vaadin.annotations.VaadinServletConfiguration;
import com.vaadin.annotations.Widgetset;
import com.vaadin.server.VaadinRequest;
import com.vaadin.server.VaadinServlet;
import com.vaadin.ui.Button;
import com.vaadin.ui.Button.ClickEvent;
import com.vaadin.ui.Label;
import com.vaadin.ui.TextField;
import com.vaadin.ui.UI;
import com.vaadin.ui.VerticalLayout;
@Theme("mytheme")
@Widgetset("my.vaadin.project.exceptionTest.MyAppWidgetset")
public class MyUI extends UI {

    @Override
    protected void init(VaadinRequest vaadinRequest) {
        final VerticalLayout layout = new VerticalLayout();
        final Calculation calculation = new Calculation();
        final Label title = new Label("Calculation");       
        layout.addComponents(title, calculation);       
        layout.setMargin(true);
        layout.setSpacing(true);        
        setContent(layout);
    }
    @WebServlet(urlPatterns = "/*", name = "MyUIServlet", asyncSupported = true)
    @VaadinServletConfiguration(ui = MyUI.class, productionMode = false)
    public static class MyUIServlet extends VaadinServlet {
    }
}

然后我有另一个类，其中包含各种字段，然后我尝试将其添加到 UI，但未成功:

package my.vaadin.project.exceptionTest;
import java.awt.Component;
import com.vaadin.ui.Button;
import com.vaadin.ui.Button.ClickEvent;
import com.vaadin.ui.CustomComponent;
import com.vaadin.ui.TextField;
import com.vaadin.ui.VerticalLayout;
import com.vaadin.event.Action;
public class Calculation extends CustomComponent{
    final VerticalLayout vl = new VerticalLayout();
    final TextField divisor = new TextField();
    final TextField dividend = new TextField();
    Button button = new Button("Click Me"); 
    public Calculation(){
        divisor.setCaption("Enter the divisor:");
        dividend.setCaption("Enter the dividend:");
        button.addClickListener( new Button.ClickListener(){
            @Override
            public void buttonClick(ClickEvent event) {
                System.out.println("this is a test");               
            }            
        });     
        vl.setMargin(true);
        vl.setSpacing(true);
        vl.addComponents(divisor, dividend, button );
    }
}

所以我的问题是，当我在 UI 课上时

layout.addComponents(title, calculation);

我收到一条错误消息:“AbstractComponentContainer 类型中的方法 addComponents(Component...) 不适用于参数(标签、计算)”我以前做过类似的事情，比如创建一个单独类的对象并将其添加到布局中，它已经起作用了，这次没有，我不确定我做错了什么。 。任何想法？谢谢

Answer 1

方法addComponents(...)仅接受Component作为参数。您的 Calculation 类未扩展/实现 Component

https://vaadin.com/api/com/vaadin/ui/AbstractComponentContainer.html#addComponents(com.vaadin.ui.Component...)