我的问题是：当我尝试使用(defun compute-cost (fixed-cost transaction-type)
(+ fixed-cost
(variable-cost transaction-type)))
(defun variable-cost (transaction-type)
(case transaction-type
((employee) 2) ; oh, an extra case we'd forgotten about!
((discount) 3)
(t 4)))
方法从数据库中获取数据时，它会崩溃。
我希望每次调用主页活动时都从数据库中获取数据，并且我无法从onStart()方法内部调用必要的方法。
onCreate()}
这是整个错误堆栈：
public class Homepage extends FragmentActivity {
Button buttonAvailability;
ListView mDrawerList;
RelativeLayout mDrawerPane;
private ActionBarDrawerToggle mDrawerToggle;
private DrawerLayout mDrawerLayout;
String email;
View backgroundimage;
Drawable background;
ListView listView;
ArrayList<NavItem> mNavItems = new ArrayList<>();
final HashMap<String, User> allUser = new HashMap<>();
final HashMap<String, Disponibilita> allDisponibilita = new HashMap<>();
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.screen_homepage);
backgroundimage = findViewById(R.id.drawerLayout);
background = backgroundimage.getBackground();
background.setAlpha(60);
setupDrawerToggle();
mNavItems.add(new NavItem("Home", "Go to homepage", R.drawable.homepage));
mNavItems.add(new NavItem("Preferences", "Change your preferences", R.drawable.ingr_icon));
mNavItems.add(new NavItem("Storico Attività", "Visuallizza tutte le attività passate e future", R.drawable.attivita));
mNavItems.add(new NavItem("Logout", "Logout from application", R.drawable.logout_icon));
// Populate the Navigation Drawer with options
mDrawerPane = (RelativeLayout) findViewById(R.id.drawerPane);
mDrawerList = (ListView) findViewById(R.id.navList);
MenuAdapter adapter = new MenuAdapter(this, mNavItems);
mDrawerList.setAdapter(adapter);
buttonAvailability = (Button) findViewById(R.id.button);
Intent intent = getIntent();
email = intent.getStringExtra("email");
final UserParser userParser = new UserParser();
final LinkedList<JSONObject> listUser = new LinkedList<>();
//Quando avvio la homepage prendo tutti gli utenti e li inserisco in un hashmap, poi prendo l'utente che
//mi interessa e apro la sua homepage
UserDao.getAllUser(listUser, new OnRestApiResultListener() {
@Override
public void onResult(Integer result) {
if (result > 0) {
User user = null;
try {
for (JSONObject object : listUser) {
user = userParser.parse(object);
allUser.put(user.getEmail(), user);
}
} catch (JSONException e) {
e.printStackTrace();
}
user = allUser.get(email);
TextView text = (TextView) findViewById(R.id.textViewWelcome);
String msg = "Welcome Dr. " + user.getSurname() + " " + user.getName();
text.setText(msg);
text.setTextSize(TypedValue.COMPLEX_UNIT_SP, 22);
}
}
@Override
public void onError(String message) {
Toast.makeText(getBaseContext(), message, Toast.LENGTH_LONG).show();
}
});
final DisponibilitaParser dispParser = new DisponibilitaParser();
final LinkedList<JSONObject> listDisponibilita = new LinkedList<>();
DisponibilitaDao.getAllDisponibilita(listDisponibilita, new OnRestApiResultListener() {
@Override
public void onResult(Integer result) {
Disponibilita disp = null;
//if (listDisponibilita.size()!=0) {
Log.d("LOL", String.valueOf(listDisponibilita.size()));
try {
for (JSONObject object : listDisponibilita) {
disp = dispParser.parse(object);
allDisponibilita.put(disp.getId(), disp);
}
} catch (JSONException e) {
e.printStackTrace();
}
//}
}
@Override
public void onError(String message) {
Toast.makeText(getBaseContext(), message, Toast.LENGTH_LONG).show();
}
});
final LinkedList<JSONObject> listRequest = new LinkedList<>();
final ArrayList<Richiesta> jsonArrayConfermate = new ArrayList<>();
final ArrayList<Richiesta> jsonArrayNonConfermate = new ArrayList<>();
final RichiestaParser ricParser = new RichiestaParser();
RichiestaDao.getAllRichiesteRicevute(email, listRequest, new OnRestApiResultListener() {
JSONObject temp;
@Override
public void onResult(Integer result) {
for (int i = 0; i < listRequest.size(); i++) {
temp = listRequest.get(i);
try {
if (temp.getInt("Confermata") == 1)
jsonArrayConfermate.add(ricParser.parse(temp));
else if (temp.getInt("Confermata") == 0)
jsonArrayNonConfermate.add(ricParser.parse(temp));
} catch (JSONException e) {
e.printStackTrace();
}
}
setAppointmentAdapter(jsonArrayConfermate);
setRequestAdapter(jsonArrayNonConfermate);
}
@Override
public void onError(String message) {
Toast.makeText(getBaseContext(), message, Toast.LENGTH_LONG).show();
}
});
// Drawer Item click listeners
mDrawerList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
if (position == 0) {
Toast.makeText(getBaseContext(), "This is the homepage!", Toast.LENGTH_LONG).show();
} else if (position == 1) {
Intent intent = new Intent(Homepage.this, UserPreferences.class);
intent.setFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
intent.putExtra("email", email);
startActivity(intent);
} else if (position == 2) {
Intent intent = new Intent(Homepage.this, HistoricalActivities.class);
intent.setFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
intent.putExtra("email", email);
startActivity(intent);
} else if (position == 3) {
Intent intent = new Intent(Homepage.this, MainActivity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);
}
mDrawerLayout.closeDrawer(GravityCompat.START);
}
});
buttonAvailability.setOnClickListener(new ClickHandlerInsert());
}
@Override
protected void onStart() {
super.onStart(); // Always call the superclass method first
Log.d("Homepage:","Chiamato onStart");
}
@Override
protected void onRestart() {
super.onRestart(); // Always call the superclass method first
// Activity being restarted from stopped state
Log.d("Homepage:","Chiamato onRestart");
}
@Override
protected void onStop() {
super.onStop(); // Always call the superclass method first
Log.d("Homepage:", "Chiamato onStop");
}
private void setAppointmentAdapter(ArrayList<Richiesta> appuntamenti){
AppointmentFragment frag = (AppointmentFragment)getFragmentManager().findFragmentById(R.id.appointments);
ArrayList<RichiestaAdapterHomepage> appointments = new ArrayList<>();
int size = appuntamenti.size();
if(size == 0){
frag.setText("There are no appointments!");
}
else{
frag.setText("The next appointments are:");
// Create the adapter to convert the array to views
Disponibilita temp;
for(Richiesta ric : appuntamenti){
temp = allDisponibilita.get(ric.getIdDisponibilita());
appointments.add( new RichiestaAdapterHomepage(ric.getId(), temp.getGiorno(), temp.getCitta(), allUser.get(ric.getMedicoRichiedente()).getSurname() + " " + allUser.get(ric.getMedicoRichiedente()).getName()) );
}
Collections.sort(appointments);
AppointmentAdapter adapter;
if(appointments.size() > 3)
adapter = new AppointmentAdapter( getApplicationContext(), appointments.subList(0, 3) );
else
adapter = new AppointmentAdapter( getApplicationContext(), appointments );
// Attach the adapter to a ListView
ListView listView = (ListView) findViewById(R.id.listAppointments);
listView.setAdapter(adapter);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
Toast.makeText(getBaseContext(), "Click element in position: " + position, Toast.LENGTH_LONG).show();
}
});
}
getFragmentManager().beginTransaction().replace(R.id.appointments, frag).addToBackStack( null ).commit();
}
private void setRequestAdapter(ArrayList<Richiesta> richieste){
RequestFragment frag = (RequestFragment)getFragmentManager().findFragmentById(R.id.requests);
ArrayList<RichiestaAdapterHomepage> requests = new ArrayList<>();
int size = richieste.size();
if(size == 0){
frag.setText("There are no new requests!");
}
else{
if (size == 1){
frag.setText("There is a new request:");
}
else {
frag.setText("There are " + size + " new requests:");
}
for(Richiesta ric : richieste){
requests.add( new RichiestaAdapterHomepage( ric.getId(), allDisponibilita.get(ric.getIdDisponibilita()).getGiorno(), "", allUser.get(ric.getMedicoRichiedente()).getSurname() + " " + allUser.get(ric.getMedicoRichiedente()).getName()) );
}
// Create the adapter to convert the array to views
Collections.sort(requests);
RequestAdapter adapter = new RequestAdapter(getApplicationContext(), requests, frag.getText());
// Attach the adapter to a ListView
listView = (ListView) findViewById(R.id.listRequests);
listView.setAdapter(adapter);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
Toast.makeText(getBaseContext(), "Click element in position: " + position, Toast.LENGTH_LONG).show();
}
});
}
getFragmentManager().beginTransaction().replace(R.id.requests, frag).addToBackStack( null ).commit();
}
private void setupDrawerToggle() {
final ActionBar actionBar = getActionBar();
if ( actionBar != null ) {
actionBar.setLogo(R.drawable.ham_icon);
actionBar.setHomeButtonEnabled(true);
actionBar.setDisplayHomeAsUpEnabled(false);
actionBar.setDisplayShowTitleEnabled(false);
}
mDrawerLayout = ( DrawerLayout ) findViewById( R.id.drawerLayout );
mDrawerToggle = new ActionBarDrawerToggle(
this,
mDrawerLayout,
new Toolbar( Homepage.this ),
R.string.apri,
R.string.chiudi
) {
@Override
public void onDrawerClosed( View drawerView ) {
super.onDrawerClosed( drawerView );
invalidateOptionsMenu();
if ( actionBar != null ) actionBar.show();
}
@Override
public void onDrawerOpened( View drawerView ) {
if ( actionBar != null && actionBar.isShowing() ) {
actionBar.hide();
}
super.onDrawerOpened( drawerView );
invalidateOptionsMenu();
}
};
mDrawerToggle.setDrawerIndicatorEnabled(true);
if(mDrawerLayout != null)
mDrawerLayout.setDrawerListener(mDrawerToggle);
//mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START);
}
@Override
protected void onPostCreate( Bundle savedInstanceState ) {
super.onPostCreate(savedInstanceState);
mDrawerToggle.syncState();
}
@Override
public boolean onMenuItemSelected( int featureId, MenuItem item ) {
switch ( item.getItemId() ) {
case android.R.id.home:
getActionBar().hide();
break;
}
return mDrawerToggle.onOptionsItemSelected( item ) || super.onOptionsItemSelected( item );
}
private class ClickHandlerInsert implements View.OnClickListener{
@Override
public void onClick(View v) {
Intent intent = new Intent(Homepage.this, Availability.class);
intent.putExtra("email", email);
//startActivityForResult(intent, 1);
startActivity(intent);
}
}
这是RequestFragment
11-09 16:17:28.584 925-925/com.example.simone.consulenzeapp E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.NullPointerException
at com.example.simone.consulenzeapp.FRAGMENT.RequestFragment.setText(RequestFragment.java:23)
at com.example.simone.consulenzeapp.ACTIVITY.Homepage.setRequestAdapter(Homepage.java:292)
at com.example.simone.consulenzeapp.ACTIVITY.Homepage.access$100(Homepage.java:53)
at com.example.simone.consulenzeapp.ACTIVITY.Homepage$3.onResult(Homepage.java:186)
at com.example.simone.consulenzeapp.DAO.RichiestaDao$4.onPostExecute(RichiestaDao.java:188)
at com.example.simone.consulenzeapp.DAO.RichiestaDao$4.onPostExecute(RichiestaDao.java:151)
at android.os.AsyncTask.finish(AsyncTask.java:631)
at android.os.AsyncTask.access$600(AsyncTask.java:177)
at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5103)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
}