我有一张表“公司”,其中包含 3 列 [名称、ID、地址]。但我只想获取“名称”列值。我正在这样做
Dao<Company, String> dao = getDBHelper().getCompanyDao();
QueryBuilder<Company, String> queryBuilder = dao.queryBuilder();
queryBuilder.orderBy(Company.USERNAME_FIELD_NAME, true);
**queryBuilder.selectColumns("name");**
PreparedQuery<Company> preparedQuery = queryBuilder.prepare();
CloseableIterator<Company> iterator = dao.iterator(preparedQuery);
AndroidDatabaseResults results = (AndroidDatabaseResults) iterator.getRawResults();
Cursor cursor = results.getRawCursor();
但是当我添加“queryBuilder.selectColumns("name")”时应用程序崩溃了。请帮助我。我想要光标,因为我正在使用光标适配器来填充数据。
崩溃日志在这里:
java.lang.NullPointerException
at com.j256.ormlite.stmt.QueryBuilder.appendFieldColumnName(QueryBuilder.java:593)
at com.j256.ormlite.stmt.QueryBuilder.appendColumns(QueryBuilder.java:585)
at com.j256.ormlite.stmt.QueryBuilder.appendStatementStart(QueryBuilder.java:405)
at com.j256.ormlite.stmt.StatementBuilder.appendStatementString(StatementBuilder.java:122)
at com.j256.ormlite.stmt.StatementBuilder.buildStatementString(StatementBuilder.java:106)
at com.j256.ormlite.stmt.StatementBuilder.prepareStatement(StatementBuilder.java:74)
at com.j256.ormlite.stmt.QueryBuilder.prepare(QueryBuilder.java:98)