Question

我使用我的数据库填充JComboBox es和DefaultComboboxModel。现在我想在我的数据库中保存Enregistrement。但我收到此错误消息

java.lang.String cannot be cast to metier.Motif

这是我的课程主题：

package metier;


public class Motif  { 

private Integer id;
private String libelle;
private Boolean recetteDepense;
Enregistrement enregistrements[];

public Motif() {
    this.id = null;
    this.libelle = "";
    this.recetteDepense = null;
}

public Motif(Integer id, String libelle, Boolean recetteDepense, Enregistrement[] enregistrements) {
    this.id = id;
    this.libelle = libelle;
    this.recetteDepense = recetteDepense;
    this.enregistrements = enregistrements;
}

public Integer getId() {
    return id;
}

public void setId(Integer id) {
    this.id = id;
}

public String getLibelle() {
    return libelle;
}

public void setLibelle(String libelle) {
    this.libelle = libelle;
}

public Boolean getRecetteDepense() {
    return recetteDepense;
}

public void setRecetteDepense(Boolean recetteDepense) {
    this.recetteDepense = recetteDepense;
}

public Enregistrement[] getEnregistrement() {
    return enregistrements;
}

public void setEnregistrement(Enregistrement[] enregistrements) {
    this.enregistrements = enregistrements;
}

@Override
public String toString() {
    return "Motif{" + "id=" + id + ", libelle=" + libelle + ", recetteDepense=" + recetteDepense + ", enregistrements=" + enregistrements + '}';
}



}

这是我保存Enregistrement：

的功能

public void enregistrerEnregistrement() throws DaoException {
    // Déclarations de variables locales
    dao = new DaoH2("gestComptes", "sa", "");
     try {
        dao.connecter();

        Motif motif = (Motif)(((VueAjouterEnregistrement)vue).getModeleJComboBoxMotif().getSelectedItem());            
        System.out.print(motif.getId());

        //dao.ajouterUnEnregistrement(id, idLibelle, idModeReglement, idCompte, idEtat, idMotif, PreLEnc, RecDep, DateEnr, montant, ancienSolde, nouveauSolde, dateFacture, numCHQ, anticipation);
    } catch (DaoException ex) {
       JOptionPane.showMessageDialog(vue, "CtrlAjouterEnregistrement - instanciation - " + ex.getMessage(), "Enregistrement", JOptionPane.ERROR_MESSAGE);
    }

    }

我的Combobox工作，但我不知道如何使用我的对象Motif的getter和setter恢复元素。

我收到此错误：

Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: java.lang.String cannot be cast to metier.Motif
at controleurs.CtrlAjouterEnregistrement.enregistrerEnregistrement(CtrlAjouterEnregistrement.java:235)
at vues.VueAjouterEnregistrement.jButtonValiderActionPerformed(VueAjouterEnregistrement.java:1288)
at vues.VueAjouterEnregistrement.access$000(VueAjouterEnregistrement.java:31)
at vues.VueAjouterEnregistrement$1.actionPerformed(VueAjouterEnregistrement.java:187)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
at java.awt.Component.processMouseEvent(Component.java:6505)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
at java.awt.Component.processEvent(Component.java:6270)
at java.awt.Container.processEvent(Container.java:2229)
at java.awt.Component.dispatchEventImpl(Component.java:4861)
at java.awt.Container.dispatchEventImpl(Container.java:2287)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
at java.awt.Container.dispatchEventImpl(Container.java:2273)
at java.awt.Window.dispatchEventImpl(Window.java:2719)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:723)
at java.awt.EventQueue.access$200(EventQueue.java:103)
at java.awt.EventQueue$3.run(EventQueue.java:682)
at java.awt.EventQueue$3.run(EventQueue.java:680)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
at java.awt.EventQueue$4.run(EventQueue.java:696)
at java.awt.EventQueue$4.run(EventQueue.java:694)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:693)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:244)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:163)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:151)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:147)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:139)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:97)

Answer 1

在这一行

Motif motif = (Motif)(((VueAjouterEnregistrement)vue)
                   .getModeleJComboBoxMotif().getSelectedItem());

您假设getSelectedItem()返回Motif，实际上它返回String。

你不应该在组合框中添加字符串，而是Motifs，并且让Motif实现toString以在GUI中正确表示。然后getSelectedItem方法将为您提供所选的Motif。

Answer 2

在这一行：

Motif motif = (Motif)(((VueAjouterEnregistrement)vue).getModeleJComboBoxMotif().getSelectedItem());

您正在尝试转换字符串（由(((VueAjouterEnregistrement)vue).getModeleJComboBoxMotif().getSelectedItem())返回）

到Motif。

这是不可能的。

您可以将Motif的构造函数添加为String作为参数，然后调用该构造函数。

修改

在你的评论中，你问我如何调用你的构造函数。恕我直言，你应该阅读一本Java书或在线教程，因为调用构造函数并不神奇。这是基本的Java。

你可以这样做：

String motifString = ((VueAjouterEnregistrement)vue).getModeleJComboBoxMotif().getSelectedItem(); Motif motif = new Motif(motifString);

错误java.lang.String无法强制转换为metier.Motif

2 个答案: