为什么我的应用程序在打开数据库时崩溃？

Question

everyone, I'm a completely new in android app development, and was trying my hand at using database to store some strings, but every time I try to open my database, my app crashes with the following error message:

android.database.sqlite.SQLiteException: near "TABLETASKS": syntax error (code 1): , while compiling: CREATE TABLETASKS(_idinteger primary key autoincrementtasktext not null);

Full code and error log follows:

package org.example.tasklist;

import java.util.ArrayList;

import android.app.Activity;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;

public class MainActivity extends Activity {

HelperMethods localhelpermethods;
OpenHelper localopenhelper;
SQLiteDatabase localdatabase;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    Context localcontext = getApplicationContext();

    localopenhelper = new OpenHelper(localcontext);
    localhelpermethods = new HelperMethods(localcontext);

    final ArrayList<String> al = new ArrayList<String>();
    ListView listView1 = (ListView)findViewById(R.id.listView1);
    final EditText editText1 = (EditText)findViewById(R.id.editText1);
    Button button1 = (Button)findViewById(R.id.button1);

    final ArrayAdapter<String> aa = new ArrayAdapter<String>           (this,android.R.layout.simple_list_item_1,al);
    listView1.setAdapter(aa);

    button1.setOnClickListener(new OnClickListener()
    {
        @Override
        public void onClick(View v) 
        { 
           localhelpermethods.open_database();
           String task = editText1.getText().toString();
           localhelpermethods.add_task(task);
           aa.notifyDataSetChanged();
        }
     });

}


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

my OpenHelper class. package org.example.tasklist;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class OpenHelper extends SQLiteOpenHelper
{


  public static final String DATABASE_NAME = "TASKS.db";
  public static final int DATABASE_VERSION = 1;
  public final String DATABASE_TABLE = "TASKS";

  //Columns in the table.
  public final String KEY_TASK = "task";
  public final String KEY_ID = "_id";

  private static Context context;

  public OpenHelper(Context context)
  {
    super(context,DATABASE_NAME,null,DATABASE_VERSION);
    this.context = context;
  }

  public void onCreate(SQLiteDatabase database)
  {
      database.execSQL("CREATE TABLE" + DATABASE_TABLE + "(" + KEY_ID + "integer primary key autoincrement" 
  + KEY_TASK + "text not null);");
  }

  public void onUpgrade(SQLiteDatabase database, int oldversion, int newversion)
  {
     if(newversion > oldversion)
     {
         database.execSQL("DROP TABLE IF EXISTS" + DATABASE_TABLE );
         onCreate(database);
     }
  }
}

My HelperMethods class.

package org.example.tasklist;

import java.util.ArrayList;

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

public class HelperMethods
{
    OpenHelper OH;
    SQLiteDatabase task_database;
    ArrayList<String> return_list = new ArrayList<String>();
    private static Context localcontext;

    public HelperMethods(Context context)
    {
        HelperMethods.localcontext = context;
        OH = new OpenHelper(localcontext);
    }

    public HelperMethods open_database() throws SQLException
    {
        task_database = OH.getWritableDatabase();
        return this;
    }

    public ArrayList<String> getAllTasks()
    { 
        String[] columns = new String[] {OH.KEY_TASK};
        Cursor cursor = task_database.query(OH.DATABASE_TABLE, columns, null, null, null, null, null, null);
        while(cursor.moveToNext())
        {
            return_list.add(cursor.getString(cursor.getColumnIndex(OH.KEY_TASK)));
        }
        return return_list;     
    }

    public void add_task(String task)
    {
        OH.getWritableDatabase();
        ContentValues cv = new ContentValues();
        cv.put(OH.KEY_TASK, task);
        task_database.insert(OH.KEY_TASK, null, cv);
        OH.close();
    }

}

logcat error output.

05-02 16:08:50.990: E/SQLiteLog(2590): (1) near "TABLETASKS": syntax error
05-02 16:08:51.020: E/AndroidRuntime(2590): FATAL EXCEPTION: main
05-02 16:08:51.020: E/AndroidRuntime(2590): Process: org.example.tasklist, PID: 2590
05-02 16:08:51.020: E/AndroidRuntime(2590): android.database.sqlite.SQLiteException: near "TABLETASKS": syntax error (code 1): , while compiling: CREATE TABLETASKS(_idinteger primary key autoincrementtasktext not null);
05-02 16:08:51.020: E/AndroidRuntime(2590):     at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
05-02 16:08:51.020: E/AndroidRuntime(2590):     at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889)
05-02 16:08:51.020: E/AndroidRuntime(2590):     at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500)
05-02 16:08:51.020: E/AndroidRuntime(2590):     at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
05-02 16:08:51.020: E/AndroidRuntime(2590):     at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
05-02 16:08:51.020: E/AndroidRuntime(2590):     at android.database.sqlite.SQLiteStatement.<init>(SQLiteStatement.java:31)
05-02 16:08:51.020: E/AndroidRuntime(2590):     at android.database.sqlite.SQLiteDatabase.executeSql(SQLiteDatabase.java:1672)
05-02 16:08:51.020: E/AndroidRuntime(2590):     at android.database.sqlite.SQLiteDatabase.execSQL(SQLiteDatabase.java:1603)
05-02 16:08:51.020: E/AndroidRuntime(2590):     at org.example.tasklist.OpenHelper.onCreate(OpenHelper.java:29)
05-02 16:08:51.020: E/AndroidRuntime(2590):     at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:252)
05-02 16:08:51.020: E/AndroidRuntime(2590):     at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:164)
05-02 16:08:51.020: E/AndroidRuntime(2590):     at org.example.tasklist.HelperMethods.open_database(HelperMethods.java:26)
05-02 16:08:51.020: E/AndroidRuntime(2590):     at org.example.tasklist.MainActivity$1.onClick(MainActivity.java:46)
05-02 16:08:51.020: E/AndroidRuntime(2590):     at android.view.View.performClick(View.java:4424)
05-02 16:08:51.020: E/AndroidRuntime(2590):     at android.view.View$PerformClick.run(View.java:18383)
05-02 16:08:51.020: E/AndroidRuntime(2590):     at android.os.Handler.handleCallback(Handler.java:733)
05-02 16:08:51.020: E/AndroidRuntime(2590):     at android.os.Handler.dispatchMessage(Handler.java:95)
05-02 16:08:51.020: E/AndroidRuntime(2590):     at android.os.Looper.loop(Looper.java:137)
05-02 16:08:51.020: E/AndroidRuntime(2590):     at android.app.ActivityThread.main(ActivityThread.java:4998)
05-02 16:08:51.020: E/AndroidRuntime(2590):     at java.lang.reflect.Method.invokeNative(Native Method)
05-02 16:08:51.020: E/AndroidRuntime(2590):     at java.lang.reflect.Method.invoke(Method.java:515)
05-02 16:08:51.020: E/AndroidRuntime(2590):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
05-02 16:08:51.020: E/AndroidRuntime(2590):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593)
05-02 16:08:51.020: E/AndroidRuntime(2590):     at dalvik.system.NativeStart.main(Native Method)

Answer 1

You have a typo: _idinteger primary key autoincrementtasktext not null

should be _idinteger primary key autoincrement tasktext not null

Note the space

Answer 2

You must have to add some space between your table row name and the datatype to identify it ,which you have missed.

Just change your create table query as below:

database.execSQL("CREATE TABLE " + DATABASE_TABLE + " ( " + KEY_ID + " integer primary key autoincrement " + KEY_TASK + " text not null); ");