我从填充一个SQLite数据库的文本和列表视图。该数据从光标正确填充（我看到列表填充文本行），但我无法看到实际的文本中的行 - 我看到的是空行。对于我的生活，我想不出什么，我无法看到的文本行数据。

I am populating a text and list view from a SQLite database. The data is populating from the cursor correctly (I see the list filling with text rows), but I'm not able to see the actual text in the rows - all I see are empty rows. For the life of me, I can't figure out what I'm not able to see the data in the text rows.

我的布局：

    <?xml version="1.0" encoding="utf-8"?>
<TabHost xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@android:id/tabhost"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<LinearLayout
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:padding="5dp">
    <TabWidget
        android:id="@android:id/tabs"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" />
    <FrameLayout
        android:id="@android:id/tabcontent"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:padding="5dp" />
 </LinearLayout>
</TabHost>

列表布局：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content">

</LinearLayout>

行布局：

<?xml version="1.0" encoding="utf-8"?>
<TextView android:id="@+id/text1"
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>

我主要的：

package com.gotquestions.gqapp;

import java.io.IOException;

import com.gotquestions.gqapp.DataBaseHelper;
import android.database.Cursor;
import android.app.TabActivity;
import android.content.Intent;
import android.content.res.Resources;
import android.database.SQLException;
import android.net.Uri;
import android.os.Bundle;
import android.widget.TabHost;

public class gqMain extends TabActivity {
/** Called when the activity is first created. */

private DataBaseHelper myDbHelper;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    Resources res = getResources(); // Resource object to get Drawables
    TabHost tabHost = getTabHost();  // The activity TabHost
    TabHost.TabSpec spec;  // Resusable TabSpec for each tab
    Intent intent;  // Reusable Intent for each tab

    // Create an Intent to launch an Activity for the tab (to be reused)
    intent = new Intent().setClass(this, TopicsActivity.class);

    // Initialize a TabSpec for each tab and add it to the TabHost
    spec = tabHost.newTabSpec("topics").setIndicator("" +
            "Topics")
                  .setContent(intent);
    tabHost.addTab(spec);

    // Do the same for the other tabs
    intent = new Intent().setClass(this, FavoritesActivity.class);
    spec = tabHost.newTabSpec("favorites").setIndicator("Favorites")
                  .setContent(intent);
    tabHost.addTab(spec);

  // Do the same for the other tabs
    intent = new Intent().setClass(this, AskActivity.class);
    spec = tabHost.newTabSpec("ask").setIndicator("Ask")
                  .setContent(intent);
    tabHost.addTab(spec);

 // Do the same for the other tabs
    intent = new Intent().setClass(this, BlogActivity.class);
    spec = tabHost.newTabSpec("blog").setIndicator("Blog")
                  .setContent(intent);
    tabHost.addTab(spec);



    tabHost.setCurrentTab(0);



    DataBaseHelper myDbHelper = new DataBaseHelper(this);
    myDbHelper = new DataBaseHelper(this);
//test
    try {

        myDbHelper.createDataBase();

    } catch (IOException ioe) {

        throw new Error("Unable to create database");

    }

    try {

        myDbHelper.openDataBase();

    }catch(SQLException sqle){

        throw sqle;

    }

    //Cursor c = myDbHelper.fetchAllTopics();


}




}

我的主题活动产生的TopicsActivity Tab..this中的数据是数据显示在列表视图，但我无法看到它。我看着光标适配器，但我只是没有看到它。

My topics activity that generates the data within the TopicsActivity Tab..this is where the data shows up in the listview, but I can't see it. I've looked at the cursor adaptor, but am just not seeing it.

package com.gotquestions.gqapp;

import com.gotquestions.gqapp.R.layout;

import android.R;
import android.app.ListActivity;
import android.database.Cursor;
import android.database.SQLException;
import android.os.Bundle;

import android.widget.SimpleCursorAdapter;

public class TopicsActivity extends ListActivity {
private DataBaseHelper myDbHelper;
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);


    //
    DataBaseHelper myDbHelper = new DataBaseHelper(this);
    myDbHelper = new DataBaseHelper(this);
//test


    try {

        myDbHelper.openDataBase();

    }catch(SQLException sqle){

        throw sqle;

    }



        setContentView(layout.list_layout);
        Cursor c = myDbHelper.fetchAllTopics();
        startManagingCursor(c);

        String[] from = new String[] { DataBaseHelper.KEY_TITLE };
        int[] to = new int[] { R.id.text1 };

        // Now create an array adapter and set it to display using our row
        SimpleCursorAdapter notes =
            new SimpleCursorAdapter(this, layout.notes_row, c, from, to);
        setListAdapter(notes);

        myDbHelper.close();








  }


}

我的数据库助手：

My database helper:

package com.gotquestions.gqapp;


import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

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

public class DataBaseHelper extends SQLiteOpenHelper{

//The Android's default system path of your application database.
private static String DB_PATH = "/data/data/com.gotquestions.gqapp/databases/";

private static String DB_NAME = "gotquestions_database.mp3";
public static final String KEY_TITLE = "topic_title";
public static final String KEY_ARTICLE_TITLE = "article_title";
public static final String KEY_ROWID = "_id";

private static final String TAG = null;

private SQLiteDatabase myDataBase; 
//
private final Context myContext;

/**
 * Constructor
 * Takes and keeps a reference of the passed context in order to access to the     application assets and resources.
 * @param context
 */
public DataBaseHelper(Context context) {

    super(context, DB_NAME, null, 1);
    this.myContext = context;
}   

/**
 * Creates a empty database on the system and rewrites it with your own database.
 * */
public void createDataBase() throws IOException{

    boolean dbExist = checkDataBase();

    if(dbExist){
        //do nothing - database already exist
    }else{

        //By calling this method and empty database will be created into the default system path
           //of your application so we are gonna be able to overwrite that database with our database.
        this.getReadableDatabase();

        try {

            copyDataBase();

        } catch (IOException e) {

            throw new Error("Error copying database");

        }
    }

   }

/**
 * Check if the database already exist to avoid re-copying the file each time you open the application.
 * @return true if it exists, false if it doesn't
 */
private boolean checkDataBase(){

    SQLiteDatabase checkDB = null;

    try{
        String myPath = DB_PATH + DB_NAME;
        checkDB = SQLiteDatabase.openDatabase(myPath, null,  SQLiteDatabase.OPEN_READONLY);

    }catch(SQLiteException e){

        //database does't exist yet.

    }

    if(checkDB != null){

        checkDB.close();

    }

    return checkDB != null ? true : false;
}

/**
 * Copies your database from your local assets-folder to the just created empty database in the
 * system folder, from where it can be accessed and handled.
 * This is done by transfering bytestream.
 * */
private void copyDataBase() throws IOException{

    //Open your local db as the input stream
    InputStream myInput = myContext.getAssets().open(DB_NAME);

    // Path to the just created empty db
    String outFileName = DB_PATH + DB_NAME;

    //Open the empty db as the output stream
    OutputStream myOutput = new FileOutputStream(outFileName);

    //transfer bytes from the inputfile to the outputfile
    byte[] buffer = new byte[1024];
    int length;
    while ((length = myInput.read(buffer))>0){
        myOutput.write(buffer, 0, length);
    }

    //Close the streams
    myOutput.flush();
    myOutput.close();
    myInput.close();

}

public void openDataBase() throws SQLException{

    //Open the database
    String myPath = DB_PATH + DB_NAME;
    myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);

}

@Override
public synchronized void close() {

        if(myDataBase != null)
            myDataBase.close();

        super.close();

}

@Override
public void onCreate(SQLiteDatabase db) {
    // TODO Auto-generated method stub

}

@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 titles");
            onCreate(db);
        }

public Cursor getTitle(long rowId) throws SQLException 
{
    Cursor mCursor =
            myDataBase.query(true, "topics", new String[] {
                    KEY_ROWID,

                    KEY_TITLE
                    }, 
                    KEY_ROWID + "=" + rowId, 
                    null,
                    null, 
                    null, 
                    null, 
                    null);
    if (mCursor != null) {
        mCursor.moveToFirst();
    }
    return mCursor;
}

public Cursor fetchAllTopics() {

    return myDataBase.query("topics", new String[] {KEY_ROWID, KEY_TITLE}, 
            null, 
            null, 
            null, 
            null, 
            null);



};

public Cursor fetchAllFavorites() {

    return myDataBase.query("articles", new String[] {
            KEY_ROWID, 

            KEY_ARTICLE_TITLE}, 
            null, 
            null, 
            null, 
            null, 
            null);



};

}

推荐答案

通过ListActivity，ID应该是

With ListActivity, the id should be

android:id="@android:id/list"

没有'+'，不应该吗？

without the '+', shouldn't it?

...回应贾森的回答。

... in response to Jason's response.