java.lang.ClassCastException：java.util.ArrayList中

Question

我運行JUnit測試，得到錯誤：

GroupOptionInputPanelTest.java：

public void setUp() {   
     groupOptionInputPanel = new GroupOptionInputPanel(TEST_ID, new Model(new ArrayList()), null); 
    } 

GroupOptionInputPanel.java：

public GroupOptionInputPanel(String id, IModel model, final Form parentForm) { 
     this(id, model, parentForm, false); 
    } 

。 ..

ListView options = new GroupElementListView("options", getSelectionGroup().getSelectionOptions(), getInitTabIndex()) { 

..

public abstract class AbstractOptionPanel extends Panel { 
public SelectionGroup getSelectionGroup() { 
     return (SelectionGroup) getModel().getObject(); 
    } 

錯誤：

java.lang.ClassCastException: java.util.ArrayList 
    at com.bgc.ordering.wizard.front.groupoptions.AbstractOptionPanel.getSelectionGroup(AbstractOptionPanel.java:33) 
    at com.bgc.ordering.wizard.front.groupoptions.GroupOptionInputPanel.<init>(GroupOptionInputPanel.java:54) 
    at com.bgc.ordering.wizard.front.groupoptions.GroupOptionInputPanel.<init>(GroupOptionInputPanel.java:47) 

我怎樣才能解決這個問題？

public GroupOptionInputPanel(String id, IModel model, final Form parentForm, final boolean canDisplayExclamationMark) { 
     super(id, model); 
     this.setOutputMarkupId(true); 

     ListView options = new GroupElementListView("options", getSelectionGroup().getSelectionOptions(), getInitTabIndex()) { 


    public Model(Serializable object) 
    { 
     setObject(object); 
    } 

模型是Wicket API。

Answer 1

您的模型由一個ArrayList實例組成，您試圖將其轉換爲SelectionGroup。 new Model(new SelectionGroup())應該修復它。