不能添加组件到布局

Question

大家好我有一个奇怪的问题，但我敢肯定我正在做一些愚蠢的事情。 在Maven项目我有我的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，我必须保持各领域，我再试图添加到用户界面，不成功另一个类：

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，当在UI类我做

layout.addComponents(title, calculation); 

我得到一个错误说：“该方法addComponents（Component等）的类型AbstractComponentContainer不适用参数（标签，计算）“ 我以前做过类似的事情，比如创建一个单独的类的对象，并将其添加到布局，它已经工作，这次它不，我不知道它是什么是我做错了......任何想法？ 谢谢

Answer 1

方法addComponents(...)只接受Component作为参数。 您Calculation类不会扩展/实现Component

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