Aula 6 - Tela de cadastro parou de funcionar ao final da aula.

Olá pessoal,

Agora, ao final da aula 6, quando clico para abrir o formulário de cadastro de Aluno aparece o seguinte erro: Interessante que quando tento alterar um cadastro já salvo ele funciona perfeitamente.

FATAL EXCEPTION: main
  Process: cadastro.caelum.com.br.cadastrocaelum, PID: 15742
  java.lang.RuntimeException: Unable to start activity ComponentInfo{cadastro.caelum.com.br.cadastrocaelum/cadastro.caelum.com.br.cadastrocaelum.FormularioActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String cadastro.caelum.com.br.cadastrocaelum.modelo.Aluno.getNome()' on a null object reference
      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3125)
      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3224)
      at android.app.ActivityThread.access$1000(ActivityThread.java:198)
      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1682)
      at android.os.Handler.dispatchMessage(Handler.java:102)
      at android.os.Looper.loop(Looper.java:145)
      at android.app.ActivityThread.main(ActivityThread.java:6843)
      at java.lang.reflect.Method.invoke(Native Method)
      at java.lang.reflect.Method.invoke(Method.java:372)
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1404)
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1199)
   Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String cadastro.caelum.com.br.cadastrocaelum.modelo.Aluno.getNome()' on a null object reference
      at cadastro.caelum.com.br.cadastrocaelum.FormularioHelper.colocaAlunoNoFormulario(FormularioHelper.java:50)
      at cadastro.caelum.com.br.cadastrocaelum.FormularioActivity.onCreate(FormularioActivity.java:37)
      at android.app.Activity.performCreate(Activity.java:6500)
      at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1120)
      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3078)
      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3224) 
      at android.app.ActivityThread.access$1000(ActivityThread.java:198) 
      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1682) 
      at android.os.Handler.dispatchMessage(Handler.java:102) 
      at android.os.Looper.loop(Looper.java:145) 
      at android.app.ActivityThread.main(ActivityThread.java:6843) 
      at java.lang.reflect.Method.invoke(Native Method) 
      at java.lang.reflect.Method.invoke(Method.java:372) 
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1404) 
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1199)

Eis aqui meu código:

FormularioActivity:

package cadastro.caelum.com.br.cadastrocaelum;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.SeekBar;
import android.widget.Toast;

import java.io.Serializable;

import cadastro.caelum.com.br.cadastrocaelum.DAO.AlunoDAO;
import cadastro.caelum.com.br.cadastrocaelum.modelo.Aluno;

/**
 * Created by Paulo on 30/11/2015.
 */
public class FormularioActivity extends Activity {


    private FormularioHelper helper;


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

        final Button botao = (Button) findViewById(R.id.botao);

        //helper = new FormularioHelper(this);
        final FormularioHelper helper = new FormularioHelper(this);

        final Aluno alunoParaSerAlterado = (Aluno) getIntent().getSerializableExtra("alunoSelecionado");

        helper.colocaAlunoNoFormulario(alunoParaSerAlterado);
        Toast.makeText(this, "Alunos:  " +  alunoParaSerAlterado, Toast.LENGTH_LONG).show();

        botao.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Aluno aluno = helper.pegaAlunoDoFormulario();
                Toast.makeText(FormularioActivity.this, "Objeto aluno criado: " + aluno.getNome(), Toast.LENGTH_LONG).show();

                AlunoDAO dao = new AlunoDAO(FormularioActivity.this);

                if (alunoParaSerAlterado != null) {
                    aluno.setId(alunoParaSerAlterado.getId());
                    botao.setText("Alterar");
                    dao.atualizar(aluno);
                } else {
                    dao.insere(aluno);
                }

                dao.close();

                finish();
            }
        });
    }
}

FormularioHelper

 package cadastro.caelum.com.br.cadastrocaelum;

import android.widget.EditText;
import android.widget.RatingBar;

import cadastro.caelum.com.br.cadastrocaelum.modelo.Aluno;

/**
 * Created by Paulo on 05/12/2015.
 */
public class FormularioHelper {

    private EditText campoNome;
    private EditText campoTelefone;
    private EditText campoEndereco;
    private EditText campoSite;
    private RatingBar campoNota;
    private Aluno camposAluno;


    public FormularioHelper(FormularioActivity activity){

        camposAluno = new Aluno();

        campoNome = (EditText) activity.findViewById(R.id.nome);
        campoTelefone = (EditText) activity.findViewById(R.id.telefone);
        campoEndereco = (EditText) activity.findViewById(R.id.endereco);
        campoSite = (EditText) activity.findViewById(R.id.site);
        campoNota = (RatingBar) activity.findViewById(R.id.nota);
    }

    public Aluno pegaAlunoDoFormulario(){
        String nome = this.campoNome.getText().toString();
        String telefone = this.campoTelefone.getText().toString();
        String endereco = this.campoEndereco.getText().toString();
        String site = this.campoSite.getText().toString();
        int nota = this.campoNota.getProgress();


        camposAluno.setNome(nome);
        camposAluno.setTelefone(telefone);
        camposAluno.setEndereco(endereco);
        camposAluno.setSite(site);
        camposAluno.setNota(Double.valueOf(nota));

        return camposAluno;
    }

    public void colocaAlunoNoFormulario(Aluno alunoParaSerAlterado) {
        campoNome.setText(alunoParaSerAlterado.getNome());
        campoEndereco.setText(alunoParaSerAlterado.getEndereco());
        campoSite.setText(alunoParaSerAlterado.getSite());
        campoTelefone.setText(alunoParaSerAlterado.getTelefone());
        campoNota.setRating(alunoParaSerAlterado.getNota().floatValue());
    }
}

AlunoDAO

 package cadastro.caelum.com.br.cadastrocaelum.DAO;

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

import java.util.ArrayList;
import java.util.List;

import cadastro.caelum.com.br.cadastrocaelum.modelo.Aluno;

/**
 * Created by Paulo on 05/12/2015.
 */
public class AlunoDAO extends SQLiteOpenHelper {

    private static final String DATABASE = "NomeDoBanco";
    private static final int VERSAO = 1;
    private static final String TABELA = "Alunos";

    public AlunoDAO(Context ctx){
        super(ctx, DATABASE, null, VERSAO);

    }

    @Override
    public void onCreate(SQLiteDatabase database) {
        String sql = "CREATE TABLE " + TABELA + " ("
                + "id INTEGER PRIMARY KEY, "
                + "nome TEXT UNIQUE NOT NULL, "
                + "telefone TEXT, "
                + "endereco TEXT, "
                + "site TEXT, "
                + "nota REAL, "
                + "caminhoFoto TEXT"
                + ");";

        database.execSQL(sql);
    }

    @Override
    public void onUpgrade(SQLiteDatabase database, int oldVersion, int newVersion) {
        String sql = "DROP TABLE IF EXISTS " + TABELA;
        database.execSQL(sql);
        onCreate(database);
    }

    public void insere(Aluno aluno){

        ContentValues values = new ContentValues();
        values.put("nome", aluno.getNome());
        values.put("telefone", aluno.getTelefone());
        values.put("endereco", aluno.getEndereco());
        values.put("site", aluno.getSite());
        values.put("nota", aluno.getNota());
        values.put("caminhoFoto", aluno.getCaminhoFoto());

        getWritableDatabase().insert(TABELA, null, values);
    }

    public List<Aluno> getLista(){

        List<Aluno> alunos = new ArrayList<Aluno>();

        String sql = "SELECT * FROM " + TABELA + ";";
        Cursor cursor = getWritableDatabase().rawQuery(sql, null);

        //laço para o cursor continuar pegando dados enquanto houver um "proximo"
        while (cursor.moveToNext()){
            Aluno aluno = new Aluno();
            aluno.setId(cursor.getLong(cursor.getColumnIndex("id")));
            aluno.setNome(cursor.getString(cursor.getColumnIndex("nome")));
            aluno.setTelefone(cursor.getString(cursor.getColumnIndex("telefone")));
            aluno.setEndereco(cursor.getString(cursor.getColumnIndex("endereco")));
            aluno.setSite(cursor.getString(cursor.getColumnIndex("site")));
            aluno.setNota(cursor.getDouble(cursor.getColumnIndex("nota")));
            aluno.setCaminhoFoto(cursor.getString(cursor.getColumnIndex("caminhoFoto")));

            alunos.add(aluno);

        }

        return alunos;
    }

    public void deletar(Aluno aluno){
        String[] args = {aluno.getId().toString()};
        getWritableDatabase().delete(TABELA, "id=?", args);
    }

    public void atualizar(Aluno aluno) {

        ContentValues values = new ContentValues();
        values.put("nome", aluno.getNome());
        values.put("telefone", aluno.getTelefone());
        values.put("endereco", aluno.getEndereco());
        values.put("site", aluno.getSite());
        values.put("nota", aluno.getNota());
        values.put("caminhoFoto", aluno.getCaminhoFoto());

        String[] args = {aluno.getId().toString()};
        getWritableDatabase().update("Alunos", values, "id=?", args);
    }
}