Question

我是Java的新手，并且已经为它开设了课程基础知识。目前我使用vaadin作为我的框架来创建一个简单的webapp但是遇到了实现手风琴的问题。我想在我的代码中有一些指针，在主应用程序中将组件转换为组件时出现错误。

到目前为止我的当前代码：

主要java类：

package Main;
import UI.Accordiontest;
import com.vaadin.ui.SplitPanel;
import com.vaadin.ui.VerticalLayout;
import com.vaadin.ui.Window;


public class test extends Application {

    private SplitPanel horizontalSplit = new SplitPanel(
            SplitPanel.ORIENTATION_HORIZONTAL);
    private Accordiontest accordion = new Accordiontest(this);

    public void init() {
        buildMainLayout();
    }


    private void buildMainLayout () {
// error: cast accordion to Component
        horizontalSplit.setFirstComponent(accordion);
//error end
        setMainWindow(new Window("test))'
        VerticalLayout layout = new VerticalLayout();
        layout.setSizeFull();
        layout.addComponent(horizontalSplit);
        layout.setExpandRatio(horizontalSplit, 1);
        getMainWindow().setContent(layout);

UI accordiontest：包UI;

import Main.test;
import com.vaadin.ui.Accordion;
import com.vaadin.ui.Label;

public class Accordiontest extends test{
    public Accordiontest(test app) {
        final Accordion accordion = new Accordion();

        for (int i = 0; i < 5;
            i++) {
        VerticalLayout layout = new VerticalLayout();
        accordion.addCOmponent(layout);
        layout.setCaption("tab" + (i + 1));
        Label label = new Label("These are the contents of Tab " + (i + 1) + ".");
        layout.addComponent(label);
        TextField textfield = new TextField("some text field");
        layout.addComponent(textfield);
         }
      } 
   }

谢谢！

Answer 1

您想要做什么，是否只想将Accordion添加到您的页面？您的代码中存在一些逻辑错误。在错误行：horizontalSplit.setFirstComponent(accordion); 您正在尝试添加accordion类型Accordiontest的对象，该类型扩展test类，test类是您的Application类，当然不是一个组件。

因此，您的继承层次结构存在问题。但是，如果您只想将Accordion添加到您的应用程序中，您可以执行以下操作：

package Main;
import UI.Accordiontest;
import com.vaadin.ui.SplitPanel;
import com.vaadin.ui.VerticalLayout;
import com.vaadin.ui.Window;


public class test extends Application {

    private SplitPanel horizontalSplit = new SplitPanel(
            SplitPanel.ORIENTATION_HORIZONTAL);
    private Accordiontest accordion = new Accordiontest();

    public void init() {
        buildMainLayout();
    }


    private void buildMainLayout () {
// No more casting errors because accordion extends Accordion which is component
        horizontalSplit.setFirstComponent(accordion);

        setMainWindow(new Window("test))'
        VerticalLayout layout = new VerticalLayout();
        layout.setSizeFull();
        layout.addComponent(horizontalSplit);
        layout.setExpandRatio(horizontalSplit, 1);
        getMainWindow().setContent(layout);
    }
 }

然后，

import Main.test;
import com.vaadin.ui.Accordion;

public class Accordiontest extends Accordion {
    public Accordiontest() {
        super();
        for (int i = 0; i < 5; i++) {
            TextField textfield = new TextField("some text field");
            addTab(textfield, "Tab" + (i+1), null);
         }
      } 
   }

使用Vaadin实现手风琴6

1 个答案: