DatabaseHelper.java

package com.commonsware.empublite;

import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.os.Process;
import org.greenrobot.eventbus.EventBus;

public class DatabaseHelper extends SQLiteOpenHelper {
  private static final String DATABASE_NAME="empublite.db";
  private static final int SCHEMA_VERSION=1;
  private static DatabaseHelper singleton=null;

  synchronized static DatabaseHelper getInstance(Context ctxt) {
    if (singleton == null) {
      singleton=new DatabaseHelper(ctxt.getApplicationContext());
    }

    return(singleton);
  }

  private DatabaseHelper(Context ctxt) {
    super(ctxt, DATABASE_NAME, null, SCHEMA_VERSION);
  }

  @Override
  public void onCreate(SQLiteDatabase db) {
    db.execSQL("CREATE TABLE notes (position INTEGER PRIMARY KEY, prose TEXT);");
  }

  @Override
  public void onUpgrade(SQLiteDatabase db, int oldVersion,
                        int newVersion) {
    throw new RuntimeException("This should not be called");
  }

  void loadNote(int position) {
    new LoadThread(position).start();
  }

  void updateNote(int position, String prose) {
    new UpdateThread(position, prose).start();
  }

  private class LoadThread extends Thread {
    private int position=-1;

    LoadThread(int position) {
      super();
      this.position=position;
    }

    @Override
    public void run() {
      Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);

      String[] args={String.valueOf(position)};
      Cursor c=
        getReadableDatabase().rawQuery("SELECT prose FROM notes WHERE position = ? ", args);

      if (c.getCount() > 0) {
        c.moveToFirst();

        EventBus.getDefault().post(new NoteLoadedEvent(position,
          c.getString(0)));
      }

      c.close();
    }
  }

  private class UpdateThread extends Thread {
    private int position=-1;
    private String prose=null;

    UpdateThread(int position, String prose) {
      super();
      this.position=position;
      this.prose=prose;
    }

    @Override
    public void run() {
      Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);

      String[] args={String.valueOf(position), prose};
      getWritableDatabase().execSQL("INSERT OR REPLACE INTO notes (position, prose) VALUES (?, ?)",
        args);
    }
  }
}