Android上的ORMLite:尝试从对象读取数据时获取NullPointerException
在我的应用程序中,我有几个持久化模型,在一个例子中,我在尝试使用相应的getter获取数据时遇到异常。但是THADB中有数据,我不知道为什么getter什么也不返回。 答案类别:Android上的ORMLite:尝试从对象读取数据时获取NullPointerException,android,ormlite,Android,Ormlite,在我的应用程序中,我有几个持久化模型,在一个例子中,我在尝试使用相应的getter获取数据时遇到异常。但是THADB中有数据,我不知道为什么getter什么也不返回。 答案类别: @DatabaseTable @JsonRootName(value = "answer") public class Answer { public Answer() {} @DatabaseField(generatedId = true, columnName = "_id")
@DatabaseTable
@JsonRootName(value = "answer")
public class Answer {
public Answer() {}
@DatabaseField(generatedId = true, columnName = "_id")
@JsonIgnore
private Integer id;
@DatabaseField
@JsonProperty(value = "id")
private Integer answer_id;
@DatabaseField(dataType = DataType.LONG_STRING)
private String text;
// some other fields and setters/getters
public String getText() {
return text;
}
public void setText(String text) {
this.text = text;
}
}
问题类别:
@DatabaseTable
public class Question extends BaseDaoEnabled implements Serializable {
private static final long serialVersionUID = -7587892134579897L;
public Question() {
}
@DatabaseField(foreign = true, foreignAutoRefresh = true)
private Answer answer;
}
任务类:
@DatabaseTable(tableName = "quests")
@JsonRootName(value = "quest")
public class Quest {
@DatabaseField(allowGeneratedIdInsert = true, generatedId = true, columnName = "_id")
private Integer id;
@DatabaseField(dataType = DataType.DATE_STRING)
Date created_at;
@DatabaseField(foreign = true)
private Survey survey;
@ForeignCollectionField(eager = false, orderColumnName = "question_id")
public Collection<Question> questions;
以及失败的代码(quest被传递到后台运行的函数中)
getAnswer()
确实返回答案。数据库中的数据保持不变。但是getText()
失败了。
有人能帮我找出我错在哪里吗?关键是
@DatabaseField(dataType=dataType.LONG\u STRING)
工作异常,我无法使它工作。切换回VARCHAR
后,问题出现了。你在哪里设置答案的文本?哦,我明白了,你确定答案是.setText(input.getText().toString());获取是否正确执行?是的,因为当我从设备(仿真器)端转储数据库时,查看它到底包含什么,我可以看到添加的数据。如何查询quest
。你能展示一下代码吗?另外,在创建添加的任务代码之后,您不需要执行更新(…)
。Quest实例被传递给函数。为什么在将引用设置为应答后不需要更新?数据类型可能会有一些问题吗?
answer.setText(input.getText().toString());
try {
if (answer.getId() == null) {
DBHelperFactory.GetHelper().getAnswersDao().create(answer);
question.setAnswer(answer);
DBHelperFactory.GetHelper().getQuestionsDao().update(question);
} else {
DBHelperFactory.GetHelper().getAnswersDao().update(answer);
}
Toast.makeText(this.getActivity(), "Answer saved", 5).show();
listener.nextQuestion();
} catch (SQLException e) {
Log.e(LOG_KEY, "Create failed", e);
}
for (Question question : quest.questions) {
if (question.getAnswer() != null) {
Log.d(LOG_KEY, question.getId().toString());
Log.d(LOG_KEY, question.getAnswer().getId().toString());
Log.d(LOG_KEY, question.getAnswer().getText());
// NullPointerException for getText().
}
}