I'm using a listview to load all database items inside it, and it works. The problem is everytime i recall that activity my listview is populated my duplicate items.
Here the code:
public class UserActivity extends ActionBarActivity{
public static ArrayList<String> ArrayofName = new ArrayList<String>();
private ListView listView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.user_activity);
DataHandler db = new DataHandler(this);
List<Data> items = db.getTitle();
listView = (ListView) findViewById(R.id.listView1);
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1, ArrayofName);
listView.setAdapter(adapter);
}
e.g. if i insert item "Facebook" it will be inserted inside my database, when i call UserActivity it will load database content(in this case Facebook item) and show all its content inside my listView. The problem is when i do this my listView show me 2 Facebook item. If i have 2 items, when i recall UserActivity it will show me 4 items.
What's wrong?
Thanks
The problem is with
public static ArrayList<String> ArrayofName = new ArrayList<String>();
It should not be static else this will be crated once and it will not initialize on the next activity recreate.Remove the static keyword and write like this-
public ArrayList<String> ArrayofName = new ArrayList<String>();
OR
Ensure the ArrayList is having no elements when you satrts populating from the database.
There are two solutions:
1.) Remove the static keyword from
public static ArrayList<String> ArrayofName = new ArrayList<String>();
If you can't remove the keyword for any reason, use solution 2.).
2.) Call the method clear() of your ArrayList before adding new entries.
Related
I'm kinda new to Android Studio so I will be grateful if you can help me with my question. How can I enter some text and add it to a ListView with the use of a Bundle?
For example, say I enter a name in the EditText component in the MainActivty, and then when I press the OK button, it will be seen in to another Activity in a List View.
I've been using Bundles to transfer text to another Activity but I can't figure out how to transfer text to ListView.
If all you want to do is display strings in your list items, you can do it fairly simply, otherwise you will have to make a custom adapter. For the former, this is what you will want to do
Create an ArrayList<String> where you will store your values that are entered from the EditText.
Create an ArrayAdapter<String> that will serve to connect the ArrayList to the ListView.
Your final code will look something like this:
public class MainActivity extends Activity {
private ListView listView;
List<String> strings;
ArrayAdapter<String> arrayAdapter;
public void onCreate(Bundle saveInstanceState) {
setContentView(R.layout.yourLayout);
listView= (ListView) findViewById(R.id.yourListView);
strings = new ArrayList<String>();
strings.add("list item 1");
strings.add("list item 2");
arrayAdapter = new ArrayAdapter<String>(
this,
android.R.layout.simple_list_item_1,
strings);
listView.setAdapter(arrayAdapter);
}
}
Then in the onClick of the "OK" button simply add the string from the EditText to the arrayList, and notify the listView that it should be updated be calling this:
arrayAdapter.notifyDataSetChanged();
I don't think you can use Bundles for what you want to achieve. Here's how I do it...
First you need to set up your list. I would use global variables:
ListView listView;
EditText editText;
ArrayList<String> strings;
ArrayAdapter<String> adapter;
Now, in onCreate() , you can do...
listView = (ListView) findViewById(R.id.your_listview);
editText = (EditText) findViewById(R.id.your_edittext );
strings = new ArrayList<>();
adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, strings);
listView.setAdapter(adapter);
You will need to set the OnClickListener for your Button. I would do this in onCreate() too:
Button button = (Button) findViewById(R.id.your_button);
button .setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// Here we get the text from the EditText component
String text = editText.getText().toString();
// Now add it to the list
strings.add(text);
// And finally, update the list
adapter.notifyDataSetChanged();
}
});
How do I get the value from EditText and save it in ListView of another Activity. Each time I give the value in EditText it should be saved permanently in the ListView one after the other. Here is my code.
MainActivity where I am retrieving edittext values into listview
public class MainActivity extends Activity {
private ListView lv;
ArrayAdapter<String> adapter;
ArrayList<String> list=new ArrayList<String>();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ActionBar bar=getActionBar();
lv=(ListView)findViewById(R.id.list);
adapter=new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, list);
lv.setAdapter(adapter);
String item=getIntent().getStringExtra("location");
adapter.add(item);
every time you add a value in EditText along with adding it to list you also need to save it somewhere else(eg.in shared preferences) so that values don't get lost while this activity reinitilizes coz that will reinitilize the list adapter as well. If not compulsary why don't you add values to list in same activity?
I have a class that extends ListActivity with a SimpleAdapter as the list adapter. My code looks like this:
public class ListOfFirms extends ListActivity {
Intent extras;
int time;
String km;
ArrayList<String> firms = new ArrayList<String>();
SimpleAdapter adapter;
static final ArrayList<HashMap<String,String>> list = new ArrayList<HashMap<String,String>>();
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.firms);
extras = getIntent();
time = extras.getIntExtra("time", 0);
km = extras.getStringExtra("km");
adapter = new SimpleAdapter(
this, list, R.layout.taxi_custom,
new String[] {"name","price"},
new int[] {R.id.taxi_name,R.id.taxi_price});
initializeFirm();
setListAdapter(adapter);
}
My question is how I can add a button to each element in the list, the button should be floating to right. My list contains object of the class Firm, how can I know which object that I grab out from the list, when a user presses this button?
here is example of custom listview which may help you
use custom adapter....
and set
listview.setAdapter(adapter);
You will have to write a CustomAdapter which extends BaseAdapter.
If you can use OnTouchListener and OnLongClickListener instead of a button it is a little easier to implement. Also if you just want to select the item, it ies easier tu use the standard built-in Android mechanisms.
Only if you REALLY need a button on each list item you have to do it like Gaurav Agarwal suggested... - which is something you might have to do sooner or later anyway :-)
I have a EditText box so a user can input names and then click the Add button and the name saves to the array playerList and clears the box so another name can be added.
I also have a ListView on the same Activity which will then be populated by the names in the Array playerList. The problem is that the ListView dosen't seem to be populated.
So I tried with a defualt set String teststring which you can see below and that populates the ListView fine. My question is how come it isn't working with the Array playerList maybe its not saving to the Array correctly?
Update just need adapter.notifyDataSetChanged(); adding to refresh the ListView Credit to #Lalit Poptani and #Jave
ArrayList<String> playerList = new ArrayList<String>();
ListView listview;
protected String[] teststring = {"Name 1", "Name 2"};
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.addremove);
ListAdapter adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, teststring);
ListView employeeList = (ListView) findViewById(R.id.namelistview);
employeeList.setAdapter(adapter);
Button confirm = (Button) findViewById(R.id.add);
confirm.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
EditText playername = (EditText) findViewById(R.id.userinput);
String name = playername.getText().toString();
playerList.add(name);
playername.setText("");
}});
To refresh the ListView after you add new data to it you have to call adapter.notifyDataSetChanged(). This is refresh your ListView will new data.
But in your case you are populating your ListView with String[] so it won't work dynamically you will have to give the size of the String[]. So, I will suggest you to populate your ListView with ArrayList itself for adding the content dynamically.
ListAdapter adapter = new ArrayAdapter<String>
(this, android.R.layout.simple_list_item_1,playerList);
You should call adapter.notifyDataSetChanged() after adding new items to make it update with the new data.
Notifies the attached observers that the underlying data has been
changed and any View reflecting the data set should refresh itself.
In my activity there is a listview containing lines of a text file. To populate this listview i created an arrayadapter in the onCreate(Bundle savedInstanceState) method. The listview is populated with items if there are lines in the file. The arrayadapter part looks like this:
final ListView lv1 = (ListView) findViewById(R.id.ListView01);
ArrayAdapter<String> adapter1;
adapter1 = new ArrayAdapter<String>(Main.this,R.layout.list_black_text,R.id.list_content, assignArr0);
lv1.setAdapter(adapter1);
adapter1.notifyDataSetChanged();
Then by clicking on Menu item1 (so now we are outside the onCreate(Bundle savedInstanceStat) method i write one line in the text file. For now everything works fine. If i exit and reopen the app the new line appears in the listview. But the listview is not refreshed after adding the new line, so at the end of the " case R.id.Menu1:" part.
So after adding one line to the file I want to refresh the listview by reading the lines from the file to an array then populating the listview with that array. Problem is that i cannot do that, even if i put the ArrayAdapter<String> adapter1; line outside the onCreate() method where the other arrays and variables are declared.
It does not see the listview (lv1 cannot be resolved).
If i define the ListView where the other variables are (ListView lv1;) this whole part of the program is not working.
I also need to empty the listview (the adapter?) by adapter1.clear(); or sg before populating it.
Any ideas are welcome.
If you need those variables to be global, you should declare them as
private final ArrayList<String> assignArr0 = new ArrayList<String>();
private ListView lv1;
private ArrayAdapter<String> adapter1;
#Override
public void onCreate(Bundle icicle)
{
lv1 = (ListView) findViewById(R.id.ListView01);
adapter1 = new ArrayAdapter<String>(Main.this,R.layout.list_black_text,
R.id.list_content, assignArr0);
lv1.setAdapter(adapter1);
}
You should set the adapter to the ListView only one time, inside the onCreate method of your activity, and the notifiyDatasetChanged should be called after you made changes to the list (the array used in your ListAdapter).
Say you have a method to add the recently read lines not yet included in your list. After adding the lines to the ArrayList used in the ListAdapter, you should call the notifyDatasetChanged method, to visualize the new items in the ListView:
private void addLinesToList(final String... newLines)
{
assignArr0.addAll(Arrays.asList(newLines));
adapter1.notifyDataSetChanged();
}
If you are reading the whole file every time it changes, and populate it from top (not just inserting the new lines), you have to first remove all the elements of the list, so the first line of the addLinesToList method should be:
assignArr0.clear();