我需要将arraylist从一个片段转移到另一个片段。我看了几篇同样问题的文章，但没有一个选项无法解决我的问题.... 来自BakeFragment
OrderFragment orderFragment = new OrderFragment();
Bundle bundle = new Bundle();
bundle.putStringArrayList(ORDER_KEY, orderList);
orderFragment.setArguments(bundle);
我需要在OrderFragment中获得这个arraylist。我是怎么做的
第一版
Bundle mBundle = this.getArguments();
orderArrayList = mBundle.getStringArrayList(ORDER_KEY);
错误：
java.lang.NullPointerException
at com.zhisheng.navdrawer.model.OrderFragment.onCreateView(OrderFragment.java:38)
at android.app.Fragment.performCreateView(Fragment.java:1699)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:885)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1057)
at android.app.BackStackRecord.run(BackStackRecord.java:682)
at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1435)
at android.app.FragmentManagerImpl$1.run(FragmentManager.java:441)
at android.os.Handler.handleCallback(Handler.java:730)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5137)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:756)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:572)
at miui.dexspy.DexspyInstaller.main(DexspyInstaller.java:171)
at dalvik.system.NativeStart.main(Native Method)
第二版
if(getArguments()!=null){
orderArrayList = this.getArguments().getStringArrayList("key");
}
不要收到错误，但没有任何反应。
public class MainActivity extends AppCompatActivity {
private DrawerLayout mDrawerLayout;
private ListView mDrawerList;
private ActionBarDrawerToggle mDrawerToggle;
// nav drawer title
private CharSequence mDrawerTitle;
// used to store app title
private CharSequence mTitle;
// slide menu items
private String[] navMenuTitles;
private TypedArray navMenuIcons;
private ArrayList<NavDrawerItem> navDrawerItems;
private NavDrawerListAdapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mTitle = mDrawerTitle = getTitle();
// load slide menu items
navMenuTitles = getResources().getStringArray(R.array.nav_drawer_items);
// nav drawer icons from resources
navMenuIcons = getResources()
.obtainTypedArray(R.array.nav_drawer_icons);
mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
mDrawerList = (ListView) findViewById(R.id.list_slidermenu);
navDrawerItems = new ArrayList<NavDrawerItem>();
// adding nav drawer items to array
// Home
navDrawerItems.add(new NavDrawerItem(navMenuTitles[0], navMenuIcons.getResourceId(0, -1)));
// Find People
navDrawerItems.add(new NavDrawerItem(navMenuTitles[1], navMenuIcons.getResourceId(1, -1)));
// Photos
navDrawerItems.add(new NavDrawerItem(navMenuTitles[2], navMenuIcons.getResourceId(2, -1)));
// Communities, Will add a counter here
navDrawerItems.add(new NavDrawerItem(navMenuTitles[3], navMenuIcons.getResourceId(3, -1)));
// Pages
navDrawerItems.add(new NavDrawerItem(navMenuTitles[4], navMenuIcons.getResourceId(4, -1)));
// What's hot, We will add a counter here
navDrawerItems.add(new NavDrawerItem(navMenuTitles[5], navMenuIcons.getResourceId(5, -1)));
navDrawerItems.add(new NavDrawerItem(navMenuTitles[6], navMenuIcons.getResourceId(6, -1)));
navDrawerItems.add(new NavDrawerItem(navMenuTitles[7], navMenuIcons.getResourceId(7, -1)));
// Find People
navDrawerItems.add(new NavDrawerItem(navMenuTitles[8], navMenuIcons.getResourceId(8, -1)));
// Photos
navDrawerItems.add(new NavDrawerItem(navMenuTitles[9], navMenuIcons.getResourceId(9, -1)));
// Communities, Will add a counter here
navDrawerItems.add(new NavDrawerItem(navMenuTitles[10], navMenuIcons.getResourceId(10, -1)));
navDrawerItems.add(new NavDrawerItem(navMenuTitles[11], navMenuIcons.getResourceId(11, -1)));
// Recycle the typed array
navMenuIcons.recycle();
mDrawerList.setOnItemClickListener(new SlideMenuClickListener());
// setting the nav drawer list adapter
adapter = new NavDrawerListAdapter(getApplicationContext(),
navDrawerItems);
mDrawerList.setAdapter(adapter);
// enabling action bar app icon and behaving it as toggle button
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setHomeButtonEnabled(true);
mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout, R.string.navigation_drawer_open, R.string.navigation_drawer_close) {
public void onDrawerClosed(View view) {
getSupportActionBar().setTitle(mTitle);
// calling onPrepareOptionsMenu() to show action bar icons
invalidateOptionsMenu();
}
public void onDrawerOpened(View drawerView) {
getSupportActionBar().setTitle(mDrawerTitle);
// calling onPrepareOptionsMenu() to hide action bar icons
invalidateOptionsMenu();
}
};
mDrawerLayout.setDrawerListener(mDrawerToggle);
if (savedInstanceState == null) {
displayView(11);
}
}
/**
* Slide menu item click listener
*/
private class SlideMenuClickListener implements
ListView.OnItemClickListener {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id) {
// display view for selected nav drawer item
displayView(position);
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// toggle nav drawer on selecting action bar app icon/title
if (mDrawerToggle.onOptionsItemSelected(item)) {
return true;
}
// Handle action bar actions click
switch (item.getItemId()) {
case R.id.action_settings:
return true;
default:
displayView(11);
//Toast.makeText(getApplicationContext(), "RasRas", Toast.LENGTH_LONG).show();
return true;
}
}
/* *
* Called when invalidateOptionsMenu() is triggered
*/
@Override
public boolean onPrepareOptionsMenu(Menu menu) {
// if nav drawer is opened, hide the action items
boolean drawerOpen = mDrawerLayout.isDrawerOpen(mDrawerList);
menu.findItem(R.id.action_settings).setVisible(!drawerOpen);
return super.onPrepareOptionsMenu(menu);
}
/**
* Diplaying fragment view for selected nav drawer list item
*/
private void displayView(int position) {
// update the main content by replacing fragments
Fragment fragment = null;
switch (position) {
case 0:
fragment = new BakeFragment();
break;
case 1:
fragment = new GarnishFragment();
break;
case 2:
fragment = new HotDishesFragment();
break;
case 3:
fragment = new DesertsFragment();
break;
case 4:
fragment = new HomeFragment();
break;
case 5:
fragment = new SnacksFragment();
break;
case 6:
fragment = new DrinkFragment();
break;
case 7:
fragment = new PizzaFragment();
break;
case 8:
fragment = new SaladFragment();
break;
case 9:
fragment = new ConfectionFragment();
break;
case 10:
fragment = new SoupFragment();
break;
case 11:
fragment = new OrderFragment();
default:
break;
}
if (fragment != null) {
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction()
.replace(R.id.frame_container, fragment).commit();
// update selected item and title, then close the drawer
mDrawerList.setItemChecked(position, true);
mDrawerList.setSelection(position);
setTitle(navMenuTitles[position]);
mDrawerLayout.closeDrawer(mDrawerList);
} else {
// error in creating fragment
Log.e("MainActivity", "Error in creating fragment");
}
}
@Override
public void setTitle(CharSequence title) {
mTitle = title;
getSupportActionBar().setTitle(mTitle);
}
/**
* When using the ActionBarDrawerToggle, you must call it during
* onPostCreate() and onConfigurationChanged()...
*/
@Override
protected void onPostCreate(Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
// Sync the toggle state after onRestoreInstanceState has occurred.
mDrawerToggle.syncState();
}
@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
// Pass any configuration change to the drawer toggls
mDrawerToggle.onConfigurationChanged(newConfig);
}
BakeFragment
public class BakeFragment extends Fragment {
final static String ORDER_KEY="key";
String myString;
ListView listView;
ArrayList<MenuItem> arrayList;
CustomAdapter customAdapter;
MenuItem menuItem;
ArrayList<String> orderList;
View rootView = null;
Integer[] quantity = {
1, 2, 3, 4, 5, 6, 7, 8, 9, 10
};
String[] bakeList = new String[]{
"Булочка с кунжутом", "Ватрушка с творогом", "Качори с чечевицей", "Лепешка \"Пападам\"",
"Лепешка \"Паратха\"", "Лепешка \"Чапати\"", "Лепешка с сыром", "Пирожное \"Корзиночка\"",
"Пирожок с капустой", "Пирожок с картофелем", "Пряник кокосовый экадашный" , "Самоса с вишней",
"Самоса с клубникой", "Самоса с малиной","Самоса с овощами и паниром", "Самоса с сухофруктами (печеная)", "Самоса с творогом", "Самоса с черной смородиной",
"Самоса с яблоком в карамели"
};
Integer[] imagesOfBakeList = new Integer[]{
R.drawable.bake1, R.drawable.bake2, R.drawable.bake3, R.drawable.bake4, R.drawable.bake5,
R.drawable.bake6, R.drawable.bake7, R.drawable.bake8, R.drawable.bake9, R.drawable.bake10,
R.drawable.bake11, R.drawable.bake12, R.drawable.bake13, R.drawable.bake14, R.drawable.bake15,
R.drawable.bake16, R.drawable.bake17, R.drawable.bake18, R.drawable.bake19
};
String[] priceOfBakeList = new String[]{
"30", "60", "60", "30", "70", "30", "70", "90", "60", "60", "60", "60", "60", "60", "60", "60",
"60", "60", "60"
};
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.list_item, container, false);
listView = (ListView)rootView.findViewById(R.id.list_of_menu_item);
orderList = new ArrayList<String>();
arrayList = new ArrayList<MenuItem>();
for(int i = 0; i < bakeList.length; i++) {
menuItem = new MenuItem(imagesOfBakeList[i], bakeList[i], priceOfBakeList[i]);
arrayList.add(menuItem);
}
customAdapter = new CustomAdapter(getActivity().getApplicationContext(), arrayList);
listView.setAdapter(customAdapter);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
View v = null;
@Override
public void onItemClick(AdapterView<?> parent, final View view, int position, long id) {
//Toast.makeText(getActivity().getApplicationContext(), "Вы заказали " + customAdapter.getItem(position), Toast.LENGTH_SHORT).show();
LayoutInflater layoutInflater = (LayoutInflater) getActivity().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = layoutInflater.inflate(R.layout.view, null);
String dishForOrderList;
final int s = customAdapter.getPrice(position);
final String dish = customAdapter.getItem(position).toString();
final String allstr;
Spinner spinner = (Spinner) v.findViewById(R.id.spinView);
final TextView orderText = (TextView) v.findViewById(R.id.order_text);
ArrayAdapter<CharSequence> spinnerAdapter = ArrayAdapter.createFromResource(getActivity(), R.array.option, android.R.layout.simple_spinner_item);
spinnerAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner.setAdapter(spinnerAdapter);
spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
String selected = parent.getSelectedItem().toString();
int t = Integer.parseInt(selected);
myString = dish + " x" + t + " " + (s * t);
String abc = dish+" x"+t+" !";
orderText.setText(myString);
Toast.makeText(getActivity(), myString, Toast.LENGTH_LONG).show();
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
}
});
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
builder.setView(v);
builder.setTitle("Сколько порций " + dish + " вы хотите заказать?");
builder.setCancelable(false);
builder.setNegativeButton("Заказать", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
orderList.add(myString);
Toast.makeText(getActivity(), orderList+"", Toast.LENGTH_LONG).show();
OrderFragment orderFragment = new OrderFragment();
Bundle bundle = new Bundle();
bundle.putStringArrayList(ORDER_KEY, orderList);
orderFragment.setArguments(bundle);
dialog.cancel();
}
});
builder.setPositiveButton("Отмена", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
dialog.cancel();
}
});
AlertDialog alertDialog = builder.create();
alertDialog.show();
}
});
return rootView;
}
}
OrderFragment
public class OrderFragment extends Fragment {
View rootView = null;
ListView orderListView;
ArrayList<String> orderArrayList;
ArrayAdapter<String> stringArrayAdapter;
final static String ORDER_KEY="key";
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.order_list, container, false);
orderArrayList = new ArrayList<String>();
Bundle mBundle = this.getArguments();
orderArrayList = mBundle.getStringArrayList(ORDER_KEY);
/* if(getArguments()!=null){
orderArrayList = this.getArguments().getStringArrayList("key");
}*/
// orderArrayList = this.getArguments()!=null? getArguments().getStringArrayList("array") : null;
//Toast.makeText(getActivity(), "d = "+orderArrayList, Toast.LENGTH_LONG).show();
// orderArrayList = bundle.getStringArrayList("key");
orderListView = (ListView)rootView.findViewById(R.id.order_list_view);
stringArrayAdapter = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, orderArrayList);
orderListView.setAdapter(stringArrayAdapter);
return rootView;
}}
答案 0 :(得分：1)
我认为您的问题可以追溯到这段代码：
public void onClick(DialogInterface dialog, int which) {
orderList.add(myString);
Toast.makeText(getActivity(), orderList+"", Toast.LENGTH_LONG).show();
OrderFragment orderFragment = new OrderFragment();
Bundle bundle = new Bundle();
bundle.putStringArrayList(ORDER_KEY, orderList);
orderFragment.setArguments(bundle);
dialog.cancel();
}
您正在尝试创建一个OrderFragment，因为单击了对话框按钮。但是，由于您未将此实例附加到活动，因此永远不会设置参数。在displayView（）方法中你有这个：
case 11:
fragment = new OrderFragment();
基本上，你所拥有的片段没有设置任何参数 - 这就是你之后无法看到它们的原因。
为了解决这个问题，我建议你采取以下几个步骤：
重新组织displayView（）方法。目前，每次调用此方法时，您都将强制创建所需片段的新实例。这可能会导致不良行为 - 性能不佳，后端堆栈的奇怪状态等。此外，在重新创建片段时，您无法从片段参数的自动保存中受益。我建议你使用标签，首先检查你想要显示的片段是否已经存在。
FragmentManager fm = getSupportFragmentManager();
Fragment fragment = fm.findByTag(THE_FRAGMENT_TAG);
if (fragment == null) {
// logic to create a fragment instance
}
// logic to show the fragment
答案 1 :(得分：0)
我唯一一次看到在FragmentTransaction中使用的OrderFragment是在MainActivity displayView方法中创建的。在那里，它没有设置参数。
你的BakeFragment会创建一个OrderFragment并设置它的参数，但它永远不会通过FragmentTransaction添加，并且只要你的onClick（DialogInterface对话框，int which）方法执行完毕就会超出范围。因此，永远不会使用带参数集的OrderFragment。
您是不是要通过使用FragmentTransaction向用户显示此片段？如果是这样，您可以让BakeFragment使用一种方法定义一个接口，该方法向监听器指示用户决定创建订单或取消订单。让MainActivity实现此接口并将自己注册为BakeFragment上的侦听器。
PS：为什么你的逻辑似乎与你的AlertDialog负面和正面按钮点击处理程序相反？