你好，我试图通过一个碎片活动的意图，但它不工作。活动在fragmentactivity初始化时关闭。以下是活动：

public class ProcuraPontoActivity extends Activity implements OnClickListener, OnItemClickListener {
    /**EditText da procura do ponto. Geralmente o input é o ID ou nome do ponto */
    private EditText procura;
    /**ListView que mostra todos os pontos encontrados */
    private ListView lv;
    /**DAO do Ponto para procurar pontos */
    private PontoDAO dao;
    /**ArrayList de Pontos encontrados */
    private ArrayList<Ponto> AL = null;
    /**ArrayList que vai pegar a ID do ponto encontrado com o nome do Ponto para mostrar na lv */
    private ArrayList<HashMap<String,String>> lista;
    /**Adaptador utilizado */
    private SimpleAdapter adapter;
    /**O usuário atual */
    private Usuario user;

    /**
     * Inicia a activity de procura de pontos.
     */
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.procura_ponto);
        lista = new ArrayList<HashMap<String,String>>();
        AL = new ArrayList<Ponto>();
        user = Usuario.toUser(getIntent().getBundleExtra("user"));

        /*
         * Widgets
         */

        procura = (EditText) findViewById(R.id.procura_ponto_et);
        Button achar = (Button) findViewById(R.id.procura_ponto_achar);
        TextView ppSigla = (TextView) findViewById(R.id.ppSigla);
        ppSigla.setText(user.getSigla());
        achar.setOnClickListener(this);
        dao = new PontoDAO(this);

        /*
         * ListView
         */
        lv = (ListView) findViewById(R.id.procura_ponto_lv);
        String[] from = new String[] { "a", "b"};
        int[] to = new int[] { R.id.pp_tv1, R.id.pp_tv2 };
        int layout = R.layout.procura_ponto_list;
        adapter = new SimpleAdapter(this ,lista, layout, from, to);
        lv.setAdapter(adapter);
        lv.setOnItemClickListener(this);

    }

    /**
     * Faz a verificação da procura e exibe resultados.
     */
    public void onClick(View v) {
        if (!(procura.getText().toString().equals(""))) {
            lista.clear();
            FiltroPonto fp = new FiltroPonto();
            fp.setNomePonto(procura.getText().toString());
            fp.setValor(1);
            AL = dao.procuraPonto(user.getSigla(),fp);
            Log.i("ProcuraPontoActivity",
                    "Número de pontos encontrados: " + AL.size());
            for (Ponto p : AL) {
                HashMap<String, String> hm = new HashMap<String, String>();
                if (p.getIdPonto().equals(null)) {
                    hm.put("a", user.getSigla()+p.getPontoNome());
                } else {
                    hm.put("a", p.getIdPonto());
                }
                hm.put("b",
                        "[UTM] E: [" + p.getUTMEste() + "] N: ["
                                + p.getUTMNorte() + "] Fuso: ["
                                + p.getUTMFuso() + "]");
                lista.add(hm);
            }
            adapter.notifyDataSetChanged();
        }
    }

    /**
     * Método chamado cada vez que um click é feito na listview percorrida
     * que vai chamar uma nova intent para iniciar o Ponto (PontoTabActivity)
     */
    public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
        PontoDAO pdao = new PontoDAO(this);
        String max = pdao.maxIdPonto(user.getIdUsuario(), user.getSigla());
        if (AL.get(arg2).getIdPonto().equals(max)) {
            Intent i = new Intent(this, PontoTabActivity.class);
            i.putExtra("id", AL.get(arg2).getIdPonto());
            i.putExtra("user", getIntent().getBundleExtra("user"));
            i.putExtra("cria", 1);
            startActivity(i);
            finish();
        } else {
            Intent i2 = new Intent(this, RelatorioPontos.class);
            i2.putExtra("id", AL.get(arg2).getIdPonto());
            startActivity(i2);
        }

    }
}

这是relatoriopontos.class：

public class RelatorioPontos extends FragmentActivity implements TabHost.OnTabChangeListener {

    private TabHost mTabHost;
    private HashMap mapTabInfo = new HashMap();
    private TabInfo mLastTab = null;

    private class TabInfo {
        private String tag;
        private Class clss;
        private Bundle args;
        private Fragment fragment;
        TabInfo(String tag, Class clazz, Bundle args) {
            this.tag = tag;
            this.clss = clazz;
            this.args = args;
        }
    }

    class TabFactory implements TabContentFactory {

        private final Context mContext;

        /**
         * @param context 
         */
        public TabFactory(Context context) {
            mContext = context;
        }

        public View createTabContent(String tag) {
            View v = new View(mContext);
            v.setMinimumWidth(0);
            v.setMinimumHeight(0);
            return v;
        }
    }

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

        initialiseTabHost(savedInstanceState);
        if (savedInstanceState != null) {
            mTabHost.setCurrentTabByTag(savedInstanceState.getString("tab"));
        }
    }   

    protected void onSaveInstanceState(Bundle outState) {
        outState.putString("tab", mTabHost.getCurrentTabTag()); //salva a tabela selecionada
        super.onSaveInstanceState(outState);
    }

    private void initialiseTabHost(Bundle args) {
        String id = getIntent().getExtras().getString("id");
        args.putString("id", id);
        mTabHost = (TabHost) findViewById(android.R.id.tabhost);
        mTabHost.setup();
        TabInfo tabInfo = null;
        RelatorioPontos.addTab(this, this.mTabHost, this.mTabHost.newTabSpec("Dados").setIndicator("Dados"),
                (tabInfo = new TabInfo("Dados", DadosPonto.class, args)));
        this.mapTabInfo.put(tabInfo.tag, tabInfo);
        RelatorioPontos.addTab(this, this.mTabHost, this.mTabHost.newTabSpec("Analises").setIndicator("Analises"),
                (tabInfo = new TabInfo("Analises", AnalisesPonto.class, args)));
        this.mapTabInfo.put(tabInfo.tag, tabInfo);
        RelatorioPontos.addTab(this, this.mTabHost, this.mTabHost.newTabSpec("Multimidia").setIndicator("Multimidia"),
                (tabInfo = new TabInfo("Multimidia", ArquivosMultimidia.class, args)));
        this.mapTabInfo.put(tabInfo.tag, tabInfo);
    }

    /**
     * @param activity
     * @param tabHost
     * @param tabSpec
     * @param clss
     * @param args 
     */
    private static void addTab(RelatorioPontos activity, TabHost tabHost, TabHost.TabSpec tabSpec, TabInfo tabInfo) {
        tabSpec.setContent(activity.new TabFactory(activity));
        String tag = tabSpec.getTag();

        tabInfo.fragment = activity.getSupportFragmentManager().findFragmentByTag(tag);
        if (tabInfo.fragment != null && !tabInfo.fragment.isDetached()) {
            FragmentTransaction ft = activity.getSupportFragmentManager().beginTransaction();
            ft.detach(tabInfo.fragment);
            ft.commit();
            activity.getSupportFragmentManager().executePendingTransactions();
        }

        tabHost.addTab(tabSpec);
    }

    public void onTabChanged(String tag) {
        TabInfo newTab = (TabInfo) this.mapTabInfo.get(tag);
        if (mLastTab != newTab) {
            FragmentTransaction ft = this.getSupportFragmentManager().beginTransaction();
            if (mLastTab != null) {
                if (mLastTab.fragment != null) {
                    ft.detach(mLastTab.fragment);
                }
            }
            if (newTab != null) {
                if (newTab.fragment == null) {
                    newTab.fragment = Fragment.instantiate(this, newTab.clss.getName(), newTab.args);
                    ft.add(R.id.realtabcontent, newTab.fragment, newTab.tag);
                } else {
                    ft.attach(newTab.fragment);
                }
            }

            mLastTab = newTab;
            ft.commit();
            this.getSupportFragmentManager().executePendingTransactions();
        }
    }

}

这是logcat：

06-06 11:45:20.661: E/AndroidRuntime(905): java.lang.RuntimeException: Unable to start activity ComponentInfo{caderneta.main.activity/caderneta.main.activity.RelatorioPontos}: java.lang.NullPointerException
06-06 11:45:20.661: E/AndroidRuntime(905):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
06-06 11:45:20.661: E/AndroidRuntime(905):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
06-06 11:45:20.661: E/AndroidRuntime(905):  at android.app.ActivityThread.access$600(ActivityThread.java:141)
06-06 11:45:20.661: E/AndroidRuntime(905):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
06-06 11:45:20.661: E/AndroidRuntime(905):  at android.os.Handler.dispatchMessage(Handler.java:99)
06-06 11:45:20.661: E/AndroidRuntime(905):  at android.os.Looper.loop(Looper.java:137)
06-06 11:45:20.661: E/AndroidRuntime(905):  at android.app.ActivityThread.main(ActivityThread.java:5041)
06-06 11:45:20.661: E/AndroidRuntime(905):  at java.lang.reflect.Method.invokeNative(Native Method)
06-06 11:45:20.661: E/AndroidRuntime(905):  at java.lang.reflect.Method.invoke(Method.java:511)
06-06 11:45:20.661: E/AndroidRuntime(905):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
06-06 11:45:20.661: E/AndroidRuntime(905):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
06-06 11:45:20.661: E/AndroidRuntime(905):  at dalvik.system.NativeStart.main(Native Method)
06-06 11:45:20.661: E/AndroidRuntime(905): Caused by: java.lang.NullPointerException
06-06 11:45:20.661: E/AndroidRuntime(905):  at caderneta.main.activity.RelatorioPontos.initialiseTabHost(RelatorioPontos.java:74)
06-06 11:45:20.661: E/AndroidRuntime(905):  at caderneta.main.activity.RelatorioPontos.onCreate(RelatorioPontos.java:61)
06-06 11:45:20.661: E/AndroidRuntime(905):  at android.app.Activity.performCreate(Activity.java:5104)
06-06 11:45:20.661: E/AndroidRuntime(905):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
06-06 11:45:20.661: E/AndroidRuntime(905):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
06-06 11:45:20.661: E/AndroidRuntime(905):  ... 11 more