cursor.getstring（）在数据库中获取错误的字段

So this is my code:

所以这是我的代码：

public void onItemClick(AdapterView<?> listView, View view, int position, long id)
{
    Cursor cursor = (Cursor) listView.getItemAtPosition(position);

    int _id = cursor.getInt(0);
    String _recipe = cursor.getString(1);
    Intent intent = new Intent(Luzon1Activity.this,RecipeInstruction.class);
    intent.putExtra("id", _id);
    intent.putExtra("recipe", _recipe);
    startActivity(intent);
}

This is my code for the next activity:

这是我下一个活动的代码：

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.recipeinstruction);

    dbHelper = new Dbadapter(this);
    dbHelper.open();
    bg = (RelativeLayout) findViewById(R.id.relativeLayout1);

    Bundle extras = getIntent().getExtras();
    if (extras != null) {
        id = extras.getInt("id");   
        recipe = extras.getString("recipe");
    }
    Toast.makeText(this, id+"\n"+recipe, Toast.LENGTH_SHORT).show();
    bg.setBackgroundResource(getImageId(this, recipe));
}

My problem is on this part: String _recipe = cursor.getString(1). It always gives me the wrong data. I tried to change the number but still it gives me the wrong data.

我的问题在于这一部分：String _recipe = cursor.getString（1）。它总是给我错误的数据。我试图更改数字，但它仍然给我错误的数据。

This is my database:

这是我的数据库：

package com.pinoycookbook;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

public class Dbadapter
{
    public static final String ROWID = "_id";
    public static final String NAME = "foodname";
    public static final String ORIGIN = "origin";

    public static final String RECIPE = "recipe";

    public static final String CATEGORY = "category";

    private static final String TAG = "Dbadapter";
    private DatabaseHelper mDbHelper;
    private SQLiteDatabase mDb;

    private static final String DATABASE_NAME = "PinoyCookbook.sqlite";
    public static final String SQLITE_TABLE = "Food";
    private static final int DATABASE_VERSION = 1;

    private final Context mCtx;

    private static final String DATABASE_CREATE =
        "CREATE TABLE if not exists " + SQLITE_TABLE + " (" +
                ROWID + " integer PRIMARY KEY autoincrement," +
                NAME + " TEXT," +
                RECIPE + " TEXT," +
                ORIGIN + " TEXT," + 
                CATEGORY+ " TEXT,"+
                " UNIQUE (" + ROWID +"));";

    private static class DatabaseHelper extends SQLiteOpenHelper
    {

        DatabaseHelper(Context context) {
            super(context, DATABASE_NAME, null, DATABASE_VERSION);
        }

        @Override
        public void onCreate(SQLiteDatabase db) {
            Log.w(TAG, DATABASE_CREATE);
            db.execSQL(DATABASE_CREATE);
        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            Log.w(TAG, "Upgrading database from version " + oldVersion + " to "
                + newVersion + ", which will destroy all old data");
            db.execSQL("DROP TABLE IF EXISTS " + SQLITE_TABLE);
            onCreate(db);
        }
    }

    public Dbadapter(Context ctx) {
        this.mCtx = ctx;
    }

    public Dbadapter open() throws SQLException {
        mDbHelper = new DatabaseHelper(mCtx);
        mDb = mDbHelper.getWritableDatabase();
        return this;
    }

    public void close() {
        if (mDbHelper != null) {
            mDbHelper.close();
        }
    }

    public long createData(String foodname, String recipe, String origin,  int i) {
        ContentValues initialValues = new ContentValues();
        initialValues.put(NAME, foodname);
        initialValues.put(RECIPE, recipe);
        initialValues.put(ORIGIN, origin);

        initialValues.put(CATEGORY, i);

        return mDb.insert(SQLITE_TABLE, null, initialValues);
    }

    public boolean deleteAllData() {
        int doneDelete = 0;
        doneDelete = mDb.delete(SQLITE_TABLE, null , null);
        Log.w(TAG, Integer.toString(doneDelete));
        return doneDelete > 0;
    }

    public void insertData() {
        createData("Adobong Manok","adobongmanok","Manila",1);
        createData("Lechon","lechon","Cebu",2);
        createData("Crispy Pata","crispypata","Cebu",2);
        createData("Bulalo","bulalo","Batangas",1);
        createData("Taba ng Talangka Rice","talangkarice","Roxas",2);
        createData("Arroz Caldo","arrozcaldo","Roxas",2);
        createData("Sinigang","sinigang","Manila",1);
    }
}

2 个解决方案

#1

So i recommend you to use getColumnIndex() method rather than hardcode it.

所以我建议你使用getColumnIndex（）方法而不是硬编码。

String _recipe = cursor.getString(cursor.getColumnIndex(Dbadapter.RECIPE));

It will ensure that you will get always right field. And if it still get wrong data problem is in query not in Cursor

它将确保您将永远得到正确的领域。如果它仍然出错，数据问题在查询中而不是在Cursor中

Note: An usage of static fields that hold column names is always the best practise.

注意：使用包含列名称的静态字段始终是最佳做法。

Update:

I've tried it before and it gives me this error: java.lang.IllegalArgumentException: column 'recipe' does not exist

我之前尝试过，它给了我这个错误：java.lang.IllegalArgumentException：列'recipe'不存在

You need to find out your actual table structure. Try to perform this statement:

您需要找出实际的表结构。尝试执行此声明：

PRAGMA table_info(Dbadapter.SQLITE_TABLE);

What says docs(source):

什么说文件（来源）：

This pragma returns one row for each column in the named table. Columns in the result set include the column name, data type, whether or not the column can be NULL, and the default value for the column. The "pk" column in the result set is zero for columns that are not part of the primary key, and is the index of the column in the primary key for columns that are part of the primary key.

该pragma为命名表中的每列返回一行。结果集中的列包括列名，数据类型，列是否可以为NULL以及列的默认值。对于不属于主键的列，结果集中的“pk”列为零，并且是主键中作为主键一部分的列的列的索引。

Example:

Here i created for you method for getting tableinfo via PRAGMA:

在这里，我为您创建了通过PRAGMA获取tableinfo的方法：

public String getTableInfo() {
    StringBuilder b = new StringBuilder("");
    Cursor c = null;
    try {
        db = helper.getReadableDatabase();
        String query = "pragma table_info(" + Dbadapter.SQLITE_TABLE + ")";
        c = db.rawQuery(query, null);
        if (c.moveToFirst()) {
            do {
                b.append("Col:" + c.getString(c.getColumnIndex("name")) + " ");                     
                b.append(c.getString(c.getColumnIndex("type")));
                b.append("\n");
            } while (c.moveToNext());
        }
        return b.toString();
    }
    finally {
        if (c != null) {
            c.close();
        }
        if (db != null) {
            db.close();
        }
    }
}

Output will be something like this:

输出将是这样的：

Column: type text
Column: date text

Only for imagination i will give you screen:

只有想象力，我会给你屏幕：

#2

you can try it this way:

你可以这样试试：

cursor.getString(cursor.getColumnIndex("recipe"));

it returns you the correct index and as result the correct value.

它会返回正确的索引，并返回正确的值。