异常：不能强制转换为java.lang.Long

Question

我遇到了异常，我不知道如何解决。

Caused by: java.lang.ClassCastException: com.xitee.ccpt.entity.ProjectRoleSkill cannot be cast to java.lang.Long

在com.xitee.ccpt.ui.project.ProjectRoleSkillGrid $ 3.buttonClick（ProjectRoleSkillGrid.java:222）〜[classes /：na]

public void buttonClick(ClickEvent event) {
    Long projectRoleSkillId = (Long) getValues().iterator().next();
    ProjectRoleSkillAddWindow projectRoleAddWindow = new ProjectRoleSkillAddWindow("Add Project Role Skill",
    new DialogWindowListener<ProjectRoleSkill>() {
        @Override
        public void dialogConfirmed(ProjectRoleSkill projectRoleSkillUpdated) {
            projectRoleSkillUpdated.setProjectRole(projectRole);
            projectRoleSkillUpdated.setProjectRoleSkillId(projectRoleSkillId);
            projectRoleSkillService.save(projectRoleSkillUpdated);
            refreshContent();
        }

        @Override
        public void dialogClosed(boolean confirmed) { }
    });
    rojectRoleAddWindow.loadToEdit(projectRoleSkillService.findProjectRoleSkillByIdForEditWindow(projectRoleSkillId));
    CcptUI.getCurrent().addWindow(projectRoleAddWindow);
}

Answer 1

Long projectRoleSkillId = (Long) getValues().iterator().next();

这不是多头。我假设getValues()返回类型为ProjectRoleSkill的可迭代对象。

为避免这种情况，请不要

public Set<Object> getValues() {
    return new HashSet<Object>(grid.getSelectedRows());
}

您应该将方法签名重写为

public Set<ProjectRoleSkill> getValues() {
    return new HashSet<>(grid.getSelectedRows());
}

这样，IDE将不允许您转换为Long。然后，您还可以看到getId()类中的ProjectRoleSkill方法。