Question

我想浏览图库中的图片并将其保存在sqlite数据库中

插入图片时出现以下错误

UserModel.findOne({ firstName: "bob" }, function(err, user) {
  UserModel.update(user, {
    $push: {
      pets: {
        $each: [{ name: "felix", type: "cat" }],
        $slice: -10
      }
    }
  }, function(err, numAffected) {
    if (err) console.log(err);
    console.log('updated');
  });
});

代码：

java.lang.NullPointerException
        at com.example.imgapp.DBAdapter.insert(DBAdapter.java:91)
        at com.example.imgapp.MainActivity.insert_img(MainActivity.java:76)

public class DBAdapter {

Context context;
DBHelper DBH;
SQLiteDatabase db;

DBAdapter(Context cx)
{
    this.context = cx;
    DBH = new DBHelper(context);

}

 String DB_name="imagesDB";
 int  DB_version=1 ;


String table_name="images";
String column1="id";
String column2="title";
String column3="image";

 String create_table="Create TABLE"+ table_name +"("+column1+" INTEGER PRIMARY KEY," + column2 +"TEXT,"+column3 +"BLOB );";


public class DBHelper extends SQLiteOpenHelper {

public DBHelper(Context context) {
    super(context, DB_name, null, DB_version);
}


@Override
public void onCreate(SQLiteDatabase db) {
    Log.v("database creation", "creating ...................");
    db.execSQL(create_table);
}

@Override
public void onUpgrade(SQLiteDatabase db, int i, int i2) {

   Log.v("upgrade database","upgrading.............");
    db.execSQL("DROP Table IF EXISTS images");
     onCreate(db);
}
 }


public  DBAdapter  open() throws SQLException
{
    DBH.getWritableDatabase();
    return this;
}

public void close()
{
    DBH.close();
}
public long insert(String title ,byte[] img )
{

    ContentValues cv=new ContentValues();
    cv.put("title",title);
    cv.put("image",img);
 return    db.insert(table_name,null,cv);

}  

}

从图像视图插入图像时出现问题问题是什么？有什么帮助吗？提前谢谢....

Answer 1

您需要保留getWritableDatabase函数的返回值并使用该函数调用insert。现在，您正在使用db变量而不初始化它而忽略了getWritableDatabase的结果。

将图像从库插入数据库

1 个答案: