TypeError: unsupported operand type(s) for +: 'int' and 'str'
时间: 2023-07-30 07:05:10 浏览: 107
<Note> notes = new ArrayList<>();
Cursor cursor = mDatabase.query(NoteOpenHelper.TABLE_NAME, null, null, null, null,这个错误通常发生在你试图将 `int` 类型的变量和 `str` 类型的变量 null, null);
while (cursor.moveToNext()) {
Note note = new Note();
note.setId(cursor.getLong(cursor.getColumnIndex(NoteOpenHelper.COL进行加法运算时。在 Python 中,`+` 运算符可以用于字符串的连接,也可以用于两_ID)));
note.setTitle(cursor.getString(cursor.getColumnIndex(NoteOpenHelper.COL_TITLE)));
note.setContent(cursor.getString(cursor.getColumnIndex(NoteOpenHelper.COL_CONTENT)));
notes.add(note);
}
cursor.close();
return notes;
}
// 搜索笔记
public List<Note>个整数的相加,但是不能将字符串和整数进行相加。
以下是一个示例代码:
```python
searchNotes(String keyword) {
List<Note> notes = new ArrayList<>();
Cursor cursor = mDatabase.query(NoteOpenHelper.TABLE_NAME,x = 10
y = "Hello"
z = x + y # 会导致 TypeError: unsupported operand type(s) for null,
NoteOpenHelper.COL_TITLE + " LIKE ? OR " + NoteOpenHelper.COL_CONTENT + " LIKE ?",
new String[] { +: 'int' and 'str'
```
在上面的示例中,我们尝试将一个整数 `x` "%" + keyword + "%", "%" + keyword + "%" }, null, null, null);
while (cursor.moveToNext()) {
Note note 和一个字符串 `y` 相加,这会导致 `TypeError` 错误。要解决这个问题,我们需要确 = new Note();
note.setId(cursor.getLong(cursor.getColumnIndex(NoteOpenHelper.COL_ID)));
note.setTitle(cursor.getString(cursor.getColumnIndex(NoteOpenHelper.COL_TITLE)));
保相加的两个变量的类型相同。
例如,我们可以将整数 `x` 转换为字符串类型, note.setContent(cursor.getString(cursor.getColumnIndex(NoteOpenHelper.COL_CONTENT)));
notes.add(note);
}
cursor.close();
return notes;
}
}
```
5. 数据库帮助类 `NoteOpenHelper.java`:
```java
public class NoteOpenHelper extends SQLiteOpenHelper {
然后再与字符串 `y` 进行连接:
```python
x = 10
y = "Hello"
z = str(x
public static final String DB_NAME = "note.db";
public static final int DB_VERSION = 1;
public static final) + y
```
在上面的示例中,我们使用 `str()` 函数将整数 `x` 转换为 String TABLE_NAME = "note";
public static final String COL_ID = "_id";
public static final String COL_TITLE = "title字符串类型,然后再与字符串 `y` 进行连接。这样就可以避免 `TypeError` 错误。
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