arraylist

问题 I have a custom ArrayList of MovieItems that I want to save and restore on screen rotation. I checked out this post - How to save custom ArrayList on Android screen rotate? - and implemented and adapted some of the codes but the saving and restoring don't seem to be working for me. 1) Saving the ArrayList: public List<MovieItem> mItems = new ArrayList<>(); @Override public void onSaveInstanceState(Bundle outState) { outState.putParcelableArrayList(MOVIE_KEY, (ArrayList<? extends Parcelable>)

问题 I have create to String array one is "word" another is "sentence". <resources> <string-array name="word"> <item> the</item> <item> a</item> <item> is</item> <item> you</item> <item> to</item> </string-array> <string-array name="sentence"> <item> the little boy</item> <item> a good boy</item> <item> is about me</item> <item> then you give</item> <item> was to come</item> </string-array> </resources> Now i am trying access these two string array from the java code. which is final String words [

问题 I'm developing an app that tracks user movement. On each onLocationChanged() I store the latitude and longitude in ArrayList<latLng> and than draw a polyline on the route. Now, when activity stopped I want to save all users activity information like: distance average pace duration all ArrayList latlng points of activity on Sqlite database to restore it later and draw a polyline with this points. The problem that I have no idea how to store the ArrayList of latitude and longitude to the

问题 Helo i am trying to populate a listView with data stored in a sqLite. After i select a product i want all the reference of that product to go on the same line like i drew in the picture. Can i make the ArrayAdapter put all records in the same xml? My code looks like this: The cursor that returns all records: public Cursor getAllRows() { String where = null; // query the DBAdapter Cursor cursor = db.query(true, TABLE_NAME, ALL_KEYS, where, null, null, null, null, null); if (cursor != null) {

问题 I have created an arraylist, and a ListView. I intend to iterate through the ListView, and checking whether they are checked or not, and then add the object (using ListView.getItem()) to my arraylist. however I get a NullPointerException. The ArrayList people_selected, is declared at top of class like this: ArrayList<PeopleDetails> selected_people; And my code: for (int i = 0; i < people_list.getCount(); i++) { item_view = people_list.getAdapter().getView(i, null, null); chBox = (CheckBox)

问题 I'm coding a project to store an array of objects, probably in an arraylist. So, my object has data elements, getters and setters. I do not have an idea how to access the elements of the object. For example my object is a book which has the following data elements. Book ->Author ->Price ->Date If the price of a certain book changes, how do I update the arrayList? Do I need a 2d arrayList? I think indexOf would not work because it is an object? Not really sure. I'm just a newbie in programming

问题 When numbers are smaller, it's quick to grow the size of an array list from 2 to 4 memory addresses but when it starts to increase the amount of space closer to the max amount of space allowed in an array list (close to the 2MB limit). Would changing how much space is allotted in those bigger areas be more efficient if it was only growing the size of the array by a fraction of the size it needs at some point? Obviously growing the size from 1mb to 2mb isn't really a big deal now-days HOWEVER,

问题 I have an ArrayList<String> statusListTextOnly; that contains some tweets. Now if I use it like this i.setAdapter(new ArrayAdapter<String>(MainActivity.this, android.R.layout.simple_list_item_1, statusListTextOnly)); Everything is fine, the activity starts and the tweets show in listview. But I wanted to go deep in my app, I want to use custom adapter. So I did: Tweet[] tweets; TweetAdapter adapter; Tweet weather_data[] = new Tweet[] { new Tweet(statusListTextOnly) }; adapter = new

问题 I have to create a method which has an ArrayList; I need to remove even numbers from this ArrayList. I have written code for that but there is a logical error which I couldn't identify. Here is my code: static void sortList(){ List <Integer> number=new ArrayList <Integer>(); number.add(11); number.add(45); number.add(12); number.add(32); number.add(36); System.out.println("Unsorted List: "+number); for (int i=0;i<number.size();i++){ int even=number.get(i)%2; if (even==0){ System.out.println(

问题 So I have an Integer[][] data that I want to convert into an ArrayList<ArrayList<Integer>> , so I tried using streams and came up with the following line: ArrayList<ArrayList<Integer>> col = Arrays.stream(data).map(i -> Arrays.stream(i).collect(Collectors.toList())).collect(Collectors.toCollection(ArrayList<ArrayList<Integer>>::new)); But the last part collect(Collectors.toCollection(ArrayList<ArrayList<Integer>>::new)) gives me an error that it cannot convert ArrayList<ArrayList<Integer>> to