「ListView」を使ってテーブル内の項目を表示したいのですが、問題があります。エラー: 列 '_id' が存在しません
テーブル名は TABKA です。テーブルには 2 つの列があります: TABKA_ID、TABKA_NAME プログラムは実行されますが、リストを表示したいときにエラーが発生します
私のコード:
DatabaseHelper.java
package com.example.sellcar;
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.database.sqlite.SQLiteQueryBuilder;
public class DatabaseHelper extends SQLiteOpenHelper{
//The Android's default system path of your application database.
String DB_PATH =null;
private static String DB_NAME = "dbSellCAR.s3db";
private SQLiteDatabase myDataBase;
private final Context myContext;
public static final String TABLE_NAME = "TABKA";
public static final String COLUMN_ID = "TABKA_ID";
public static final String COLUMN_TITLE = "TABKA_NAME";
/**
* 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;
DB_PATH="/data/data/"+context.getPackageName()+"/"+"databases/";
}
/**
* 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_READWRITE);
}
@Override
public synchronized void close() {
if(myDataBase != null)
myDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
public Cursor getCursor()
{
SQLiteQueryBuilder queryBuilder = new SQLiteQueryBuilder();
queryBuilder.setTables(TABLE_NAME);
String[] asColumnsToReturn = new String[] {COLUMN_ID,COLUMN_TITLE};
Cursor mCursor = queryBuilder.query(myDataBase, asColumnsToReturn, null, null, null, null, null);
return mCursor;
}
//return name column
public String getName(Cursor c){
return c.getString(1);
}
//return executeSQL
public void dodaj(String sql){
myDataBase.execSQL(sql);
}
}
ListOfOffers.java
package com.example.sellcar;
import java.io.IOException;
import android.app.Activity;
import android.content.Context;
import android.database.Cursor;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.CursorAdapter;
import android.widget.ListView;
import android.widget.TextView;
public class ListOfOffers extends Activity{
private DatabaseHelper myDatabaseHelper = null;
private Cursor myCursor = null;
private myAdapter adapter=null;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
try {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ListView myListView=(ListView) findViewById(R.id.myListView1);
DatabaseHelper dbDatabaseHelper = new DatabaseHelper(this);
dbDatabaseHelper.createDataBase();
dbDatabaseHelper.openDataBase();
myCursor=dbDatabaseHelper.getCursor();
startManagingCursor(myCursor);
adapter=new myAdapter(myCursor);
myListView.setAdapter(adapter);
} catch (IOException e) {
// TODO Auto-generated catch block
Log.e("BŁAD !","To jest bład w kodzie: "+e.toString());
e.printStackTrace();
}
}
class myAdapter extends CursorAdapter{
myAdapter(Cursor c){
super(ListOfOffers.this,c);
}
public void bindView(View row, Context ctxt,Cursor c) {
myHolder holder=(myHolder)row.getTag();
holder.populateFrom(c, myDatabaseHelper);
}
@Override
public View newView(Context ctxt, Cursor c,ViewGroup parent){
LayoutInflater inflater=getLayoutInflater();
View row=inflater.inflate(R.layout.row_offer,parent,false);
myHolder holder=new myHolder(row);
row.setTag(holder);
return(row);
}
}
static class myHolder {
private TextView tvNazwa=null;
myHolder(View row) {
tvNazwa=(TextView)row.findViewById(R.id.tvRowOffer);
}
void populateFrom(Cursor c,DatabaseHelper dbDH){
tvNazwa.setText(dbDH.getName(c));
}
}
}