Saya mengisi tampilan teks dan daftar dari database SQLite. Data terisi dari kursor dengan benar (saya melihat daftar terisi dengan baris teks), tetapi saya tidak dapat melihat teks sebenarnya di baris tersebut - yang saya lihat hanyalah baris kosong. Seumur hidup saya, saya tidak tahu apa yang saya tidak dapat melihat data di baris teks.
Tata letak saya:
<?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>
tata letak daftar:
<?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>
row layout:
<?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"/>
Utama saya:
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();
}
}
Aktivitas topik saya yang menghasilkan data dalam Tab TopicsActivity..di sinilah data muncul di tampilan daftar, tetapi saya tidak dapat melihatnya. Saya telah melihat adaptor kursor, tetapi saya tidak melihatnya.
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();
}
}
Pembantu basis data saya:
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);
};
}
