Implementação básica do padrão repository (http://martinfowler.com/eaaCatalog/repository.html) no Android.

Entity.java

package br.edu.fa7.exemplo.domain.entities;

import java.io.Serializable;

public class Entity implements Serializable {
	private long id;
	
	public Entity() {
	    this.id = 0;	
	}
	
	Entity(long id) {
	    this.id = id;
	}
	
        public void setId(int id) {
             this.id = id;
        }
	public long getId() {
		return id;
	}
	
	public boolean isPersisted() {
		return this.id > 0;
	}
}

Exemplo.java

package br.edu.fa7.exemplo.domain.entities;

import java.io.Serializable;

public class Exemplo extends Entity implements Serializable {
	
	private String nome;
        private String telefone;

        public Exemplo(long id, String nome, String telefone) {
            this.nome = nome;
            this.telefone = telefone;
        }

        public String getNome() {
		return nome;
	}
	public void setNome(String nome) {
		this.nome = nome;
	}
        public String getTelefone() {
		return telefone;
	}
	public void setTelefone(String telefone) {
		this.telefone = telefone;
	}
}

ExemploRepository.java

package br.edu.fa7.exemplo.domain.repositories;

import br.edu.fa7.exemplo.domain.entities.Fugitivo;

public interface ExemploRepository extends Repository<Exemplo> {

}

ExemploRepositoryImpl.java

package br.edu.fa7.exemplo.infrastructure.repositories;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import br.edu.fa7.exemplo.domain.entities.Fugitivo;
import br.edu.fa7.exemplo.domain.repositories.FugitivoRepository;

public class ExemploRepositoryImpl extends SQLiteRepository<Exemplo> implements ExemploRepository {


	private final static String NOME = "nome";
	private final static String TELEFONE = "telefone";
	
	private String[] columns;
	
	public ExemploRepositoryImpl(Context context) {
		super(context);
	}
	
	@Override
	protected String[] getColumns() {
		if (columns == null) {
			columns = new String[] { ID, NOME, TELEFONE };
		}
		
		return columns;
	}
	
	@Override
	protected Exemplo fill(Cursor c) {
		
		long id = c.getLong(c.getColumnIndex(ID));
		String telefone = c.getString(c.getColumnIndex(TELEFONE));
		String nome = c.getString(c.getColumnIndex(NOME));
		
		return new Fugitivo(id, nome, telefone);
	}
	
	@Override
	protected ContentValues getValues(Exemplo entity) {
		ContentValues values = new ContentValues();
		
		values.put(TELEFONE, entity.getTelefone());
		values.put(NOME, entity.getNome());
		
		return values;
	}
}

Repository.java

package br.edu.fa7.exemplo.domain.repositories;

import java.util.List;

import br.edu.fa7.exemplo.domain.entities.Entity;

public interface Repository<E extends Entity> {
	
	void add(E entity);
	
	int remove(E entity);
	
	int remove(long id);
	
	void update(E entity);
	
	List<E> list();
	
	E get(long id);
}

SQLiteRepository.java

package br.edu.fa7.exemplo.infrastructure.repositories;

import java.lang.reflect.ParameterizedType;
import java.util.ArrayList;
import java.util.List;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.util.Log;
import br.edu.fa7.exemplo.domain.entities.Entity;
import br.edu.fa7.exemplo.domain.repositories.Repository;

public abstract class SQLiteRepository<E extends Entity> implements Repository<E> {

	protected final static String ID = "_id";
	
	private SQLiteDatabase database;
	
	private DatabaseExemploHelper helper;
	
	private Context context;
	
	private String tableName;
	
	public SQLiteRepository(Context context) {
		this.tableName = getEntityName();
		this.context = context;
		buildDatabase();
	}
	
	private String getEntityName() {
		ParameterizedType p = (ParameterizedType)getClass().getGenericSuperclass();
		String txt = ((Class<E>)p.getActualTypeArguments()[0]).getSimpleName();
		
		return txt.toLowerCase();
	}	
	
	private void buildDatabase() {
		if (helper == null) {
			helper = new DatabaseExemploHelper(context);
			database = helper.getWritableDatabase();
		}
	}
	
	protected SQLiteDatabase getDatabase() {
		if (database == null) {
			buildDatabase();
		}
		
		return database;
	}
	
	@Override
	public void add(E entity) {
		ContentValues values = getValues(entity);
		long id = database.insert(tableName, null, values);
                entity.setId(id);
	}
	
	@Override
	public void update(E entity) {
		ContentValues values = getValues(entity);
		int rows = database.update(tableName, values, "_id=?", new String[] { String.valueOf(entity.getId()) });
	}

	@Override
	public int remove(E entity) {
		return remove(entity.getId());
	}

	@Override
	public int remove(long id) {
		int rows = database.delete(tableName, "_id=?", new String[] { String.valueOf(id) });
		return rows;
	}

	@Override
	public List<E> list() {
		List<E> list = new ArrayList<E>();
		
		Cursor c = getDatabase().query(tableName, getColumns(), null, null, null, null, null);
		
		c.moveToFirst();
		
		while (c.moveToNext()) {
			E entity = fill(c);
			list.add(entity);
		}

                c.close();
		
		return list;
	}

	@Override
	public E get(long id) {
		Cursor c = getDatabase().query(tableName, getColumns(), "_id=?", new String[] { String.valueOf(id) }, null, null, null);
		
		return fill(c);
	}
	
	protected abstract E fill(Cursor c);
	
	protected abstract ContentValues getValues(E entity);
	
	protected abstract String[] getColumns();
}