Question

我正在尝试在ListView中显示来自SQLiteDatabase的数据，但是我收到错误：引起：android.database.sqlite.SQLiteException：没有这样的表：Studenten（代码1）:,编译时：DELETE FROM Studenten

这是我的代码（来自StudentDBAdapter）：

 package com.ipmedt4.challengeweek_v2;

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

/**
* Created by Charlie on 28-12-2014.
*/
public class StudentDBAdapter {
public static final String KEY_ROWID = "_id";
public static final String KEY_NAAM = "_naam";
public static final String KEY_STUDENTNUMMER = "_studentnummer";
public static final String KEY_KLAS = "_klas";
public static final String KEY_CIJFER = "_cijfer";
public static final String KEY_OPMERKINGEN = "_opmerkingen";

private static  final String TAG = "StudentDBAdapter";
private DatabaseHelper mDbHelper;
private SQLiteDatabase mDB;

private static final String DATABASE_NAME = "Challengeweek";
private static final String SQLITE_TABLE = "Studenten";
private static final int DATABASE_VERSION = 1;

private final Context mCtx;

private static final String DATABASE_CREATE = "CREATE TABLE IF NOT EXISTS" + SQLITE_TABLE + "(" +
        KEY_ROWID + "INTEGER PRIMARY KEY AUTOINCREMENT," + KEY_NAAM + "," + KEY_STUDENTNUMMER + ","
        + KEY_KLAS + "," + KEY_CIJFER + "," + KEY_OPMERKINGEN + "," + ")";

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);
    }

    @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 StudentDBAdapter (Context ctx){
    this.mCtx = ctx;
}
public StudentDBAdapter open () throws SQLiteException{
    mDbHelper = new DatabaseHelper(mCtx);
    mDB = mDbHelper.getWritableDatabase();
    return this;
}

public void close() {
    if (mDbHelper != null) {
        mDbHelper.close();
    }
}
public long createStudent (String naam, String studentnummer, String klas){
    ContentValues initialValues = new ContentValues();
    initialValues.put(KEY_NAAM, naam);
    initialValues.put(KEY_STUDENTNUMMER, studentnummer);
    initialValues.put(KEY_KLAS, klas);

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

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

}

public Cursor fetchStudentenbyName(String inputText) throws SQLiteException{
Log.w(TAG, inputText);
Cursor mCursor = null;
    if (inputText == null || inputText.length() == 0){
        mCursor = mDB.query(SQLITE_TABLE, new String[] {
                KEY_ROWID, KEY_NAAM, KEY_STUDENTNUMMER, KEY_KLAS
        }, null, null, null, null, null);
    }
    else {
        mCursor = mDB.query(true, SQLITE_TABLE, new String [] {KEY_ROWID,
        KEY_NAAM, KEY_STUDENTNUMMER, KEY_KLAS}, KEY_NAAM + "like '%" + inputText +
        "%'", null, null, null, null, null);
    }
    if (mCursor != null) {
        mCursor.moveToFirst();
    }
    return mCursor;
}

   public Cursor showAlleStudenten(){
   Cursor mCursor = mDB.query(SQLITE_TABLE, new String[] {KEY_ROWID, KEY_NAAM, KEY_STUDENTNUMMER,
   KEY_KLAS}, null, null, null, null, null);

   if (mCursor != null){
       mCursor.moveToFirst();
   }
   return mCursor;
    }
    public void insertStudenten(){
      createStudent("Adel, Pieter", "s1078455", "INF1G");
    createStudent("Adel, Pieter", "s1078455", "INF1G");
    createStudent("Adel, Pieter", "s1078455", "INF1G");
    createStudent("Adel, Pieter", "s1078455", "INF1G");
    createStudent("Adel, Pieter", "s1078455", "INF1G");
    createStudent("Adel, Pieter", "s1078455", "INF1G");
    createStudent("Adel, Pieter", "s1078455", "INF1G");
    createStudent("Adel, Pieter", "s1078455", "INF1G");
    createStudent("Adel, Pieter", "s1078455", "INF1G");
    createStudent("Adel, Pieter", "s1078455", "INF1G");
    createStudent("Adel, Pieter", "s1078455", "INF1G");
    createStudent("Adel, Pieter", "s1078455", "INF1G");


}
}

这来自实现ListView的类：

package com.ipmedt4.challengeweek_v2;

import android.annotation.TargetApi;
import android.app.Activity;
import android.app.ListActivity;
import android.content.Context;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
import android.os.Build;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.FilterQueryProvider;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
import android.widget.Toast;

import java.util.ArrayList;


public class OverzichtStudenten extends Activity {
private StudentDBAdapter dbHelper;
private SimpleCursorAdapter dataAdapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_overzicht_studenten);
    dbHelper = new StudentDBAdapter(this);
    dbHelper.open();

    //maak alle data schoon
    dbHelper.deleteAllStudenten();

    //toevoegen van data
    dbHelper.insertStudenten();

    //genereren ListView van SQLiteDatabase
    displayListView();

}
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
private void displayListView(){
    Cursor cursor = dbHelper.showAlleStudenten();

    //selecteer gewenste kolommen
    String[] columns = new String[]{
            StudentDBAdapter.KEY_NAAM,
            StudentDBAdapter.KEY_STUDENTNUMMER,
            StudentDBAdapter.KEY_KLAS
    };

    //In XML gedefiniërde Views
    int[] to = new int[]{
      R.id.naam,
      R.id.studentnummer,
      R.id.klas
    };


    dataAdapter = new SimpleCursorAdapter(
            this, R.layout.student_info,
            cursor,
            columns,
            to,
            0);

    ListView listView = (ListView) findViewById(R.id.listView1);
    listView.setAdapter(dataAdapter);

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

            String studentNaam = cursor.getString(cursor.getColumnIndexOrThrow("naam"));
            Toast.makeText(getApplicationContext(),
                    studentNaam, Toast.LENGTH_SHORT).show();
        }
    });

    EditText myFilter = (EditText) findViewById(R.id.myFilter);
    myFilter.addTextChangedListener(new TextWatcher() {
        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) {

        }

        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {
            { dataAdapter.getFilter().filter(s.toString());
        }}

        @Override
        public void afterTextChanged(Editable s) {

        }
    });
    dataAdapter.setFilterQueryProvider(new FilterQueryProvider() {
        @Override
        public Cursor runQuery(CharSequence constraint) {
            return dbHelper.fetchStudentenbyName(constraint.toString());
        }
    });
}




@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_overzicht_studenten, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}
}

我无法弄明白。我希望你能帮助我。

Answer 1

您实际上从未创建过表格 - 您的SQLiteOpenHelper.onCreate()为空。

引起：android.database.sqlite.SQLiteException：没有这样的表，同时编译DELETE FROM

1 个答案: