Android SQLite数据库增删改查操作代码示例及错误分析

在Android开发中，使用SQLite数据库进行数据存储是常见的做法。本文将提供一个完整的SQLite数据库增删改查操作代码示例，并分析其中 updateNote 方法存在的错误以及解决方案，帮助你更好地理解和使用SQLite数据库。

代码示例

以下是一个名为 ZSGC 的类的代码，它封装了对SQLite数据库进行增删改查的操作：javapublic class ZSGC { SQLiteOpenHelper dbHandler; SQLiteDatabase db;

private static final String[] columns = {            NoteDatabase.ID,            NoteDatabase.CONTENT,            NoteDatabase.TIME,            NoteDatabase.MODE    };

public ZSGC(Context context){        dbHandler=new NoteDatabase(context);    }

public void open(){        db=dbHandler.getWritableDatabase();    }    public void close(){        dbHandler.close();    }

//把note 加入到database里面    public Note addNote(Note note){        //add a note object to datebase        ContentValues contentValues =new ContentValues();        contentValues.put(NoteDatabase.CONTENT,note.getContent());        contentValues.put(NoteDatabase.TIME,note.getTime());        contentValues.put(NoteDatabase.MODE,note.getTag());        long insertId =db.insert(NoteDatabase.TABLE_NAME,null,contentValues);        note.setId(insertId);        return note;    }

public Note getNote(long id){        //get a note from database using cursor index        Cursor cursor = db.query(NoteDatabase.TABLE_NAME,columns,NoteDatabase.ID+'=?',                new String[]{String.valueOf(id)},null,null,null,null);        if(cursor!=null)            cursor.moveToFirst();        Note e =new Note(cursor.getString(1),cursor.getString(2),cursor.getInt(3));        return e;    }

@SuppressLint('Range')    public List<Note>getAllNotes(){        Cursor cursor=db.query(NoteDatabase.TABLE_NAME,columns,null,null,null,null,null);

    List<Note> notes =new ArrayList<>();        if(cursor.getCount()>0){            while (cursor.moveToNext()){                Note note =new Note();                note.setId(cursor.getLong(cursor.getColumnIndex(NoteDatabase.ID)));                note.setContent(cursor.getString(cursor.getColumnIndex(NoteDatabase.CONTENT)));                note.setTime(cursor.getString(cursor.getColumnIndex(NoteDatabase.TIME)));                note.setTag(cursor.getInt(cursor.getColumnIndex(NoteDatabase.MODE)));                notes.add(note);            }        }        return notes;    }

public int updateNote(Note note){        //update the info of an existing note        ContentValues values =new ContentValues();        values.put(NoteDatabase.CONTENT,note.getContent());        values.put(NoteDatabase.TIME,note.getTime());        values.put(NoteDatabase.MODE,note.getTag());        //updating row        return db.update(NoteDatabase.TABLE_NAME,values,                NoteDatabase.ID + ' = ' , new String[]{String.valueOf(note.getId())});    }

public void removeNote(Note note){        //remove a note according to ID value        db.delete(NoteDatabase.TABLE_NAME,NoteDatabase.ID + ' = ' + note.getId(),null);