hi
why load text from String array and set text to textview is very slow in big string array?
please help to me.
//get khotbe text from database and copy to khotbe activity
private void setkhotbetextarabicfarsi() {
this.sqliteDB = SQLiteDatabase.openOrCreateDatabase(this.getDatabasePath("aliname").getPath(), (SQLiteDatabase.CursorFactory) null);
Itemid = this.getIntent().getIntExtra("selectedFromListid", 1);
Cursor cursorLines = this.sqliteDB.rawQuery("SELECT * FROM khotbe where IDFehrest=" + this.Itemid , (String[]) null);
allrecs = cursorLines.getCount();
matn = new String[allrecs];
if (this.allrecs != 0) {
cursorLines.moveToFirst();
for (int i = 0; i < this.allrecs; ++i) {
String TextArabicOfKhotbe = cursorLines.getString(cursorLines.getColumnIndex("TextArabicOfKhotbe"));
int IDkhotbe = cursorLines.getInt(cursorLines.getColumnIndex("IDkhotbe"));
this.matn[i] = TextArabicOfKhotbe;
cursorLines.moveToNext();
}
}
and main code:
for(int var1 = 0; var1 < this.allrecs; ++var1) {
tvArabic = new JustifiedTextView(this);
tvArabic.setText(matn[var1]);
you are creating the textviews in loop that might making it slow.. try populating the array values using an adapter..
Also check the number of rows you are accessing from the DB. if they are huge in number, they would require more time to be fetched.
Use limit in that case.
I have 16 buttons, whose names are "button1", "button2", and so on. Is there a way I can iterate through them using a for loop, by somehow appending the number value upon each iteration? Something like this:
for(int i = 1; i<17; i++ ){
Button b = (Button)findViewById(R.id.buttoni);
I know I can simply initialize each button in my onCreate() method, but I was just curious if I could do it in a way similar to my example code.
Thank you.
You can use getIdentifier :
for(int i = 1; i<17; i++ ){
int buttonId = getResources().getIdentifier("button"+i, "id", getPackageName());
Button b = (Button)findViewById(buttonId);
//Your stuff with the button
}
You can create an array of Button's and use getIdentifier method that allows you to get an identifier by its name.
final int number = 17;
final Button[] buttons = new Button[number];
final Resources resources = getResources();
for (int i = 0; i < number; i++) {
final String name = "btn" + (i + 1);
final int id = resources.getIdentifier(name, "id", getPackageName());
buttons[i] = (Button) findViewById(id);
}
In case someone is interested how to achive the same result using Java only
The solution above uses Android specific methods (such as getResources, getIdentifier) and can not be used in usual Java, but we can use a reflection and write a method that works like a getIdentifier:
public static int getIdByName(final String name) {
try {
final Field field = R.id.class.getDeclaredField(name);
field.setAccessible(true);
return field.getInt(null);
} catch (Exception ignore) {
return -1;
}
}
And then:
final Button[] buttons = new Button[17];
for (int i = 0; i < buttons.length; i++) {
buttons[i] = (Button) findViewById(getIdByName("btn" + (i + 1)));
}
NOTE:
Instead of optimizing this kind of code you should rethink your layout. If you have 17 buttons on the screen, a ListView is probably the better solution. You can access the items via index and handle onClick events just like with the buttons.
I have an array adapter(string), and would like to convert it to a List<String>, but after a little googling and a few attempts, I am no closer to figuring out how to do this.
I have tried the following;
for(int i = 0; i < adapter./*what?*/; i++){
//get each item and add it to the list
}
but this doesn't work because there appears to be no adapter.length or adapter.size() method or variable.
I then tried this type of for loop
for (String s: adapter){
//add s to the list
}
but adapter can't be used in a foreach loop.
Then I did some googling for a method (in Arrays) that converts from an adapter to a list, but found nothing.
What is the best way to do this? Is it even possible?
for(int i = 0; i < adapter.getCount(); i++){
String str = (String)adapter.getItem(i);
}
Try this
// Note to the clown who attempted to edit this code.
// this is an input parameter to this code.
ArrayAdapter blammo;
List<String> kapow = new LinkedList<String>(); // ArrayList if you prefer.
for (int index = 0; index < blammo.getCount(); ++index)
{
String value = (String)blammo.getItem(index);
// Option 2: String value = (blammo.getItem(index)).toString();
kapow.add(value);
}
// kapow is a List<String> that contains each element in the blammo ArrayAdapter.
Use option 2 if the elements of the ArrayAdapter are not Strings.
I'm working on code that takes two arrays with strings (the strings are just sentences) and allocates them to classes which are held in another array (The Sentence class array shown below in the code).
So here's my problem. When popList() is called, the for loop runs through twice and works fine, putting the first index of addStrings and addTranslation into the first class in the array. However, when the loop indexes up and runs temp.sentence = addStrings[1] again, it OVERRIDES the first class's .sentence also. Then when temp.translations = addTranslations[1] runs again it OVERRIDES the first class's .translation.
So by the end of the loop, all of the arrays are filled with the same thing: the last index of addStrings and addTranslation. Every time it loops it overwrites all the indices before it with the index it's supposed to be putting in.
Anyone know what the problem is here? Thanks!
public class Sentence {
public String sentence;
public String translation;
Sentence() {
sentence = " ";
translation = " ";
}
}
private void popStrings() {
addStrings[0] = "我是你的朋友。"; addTranslations[0] = "I am your friend.";
addStrings[1] = "你可以帮助我吗？"; addTranslations[1] = "Could you help me?";
addStrings[2] = "我不想吃啊!"; addTranslations[2] = "I don't want to eat!";
}
//Fill Sentence array with string and translation arrays
private void popList() {
int i = 0;
Sentence temp = new Sentence();
for(i = 0; i < addStrings.length && i < addTranslations.length ; i++) {
temp.sentence = addStrings[i];
temp.translation = addTranslations[i];
sentences[i] = temp;
}
}
You need to create new Sentence() inside the loop:
for(i = 0; i < addStrings.length && i < addTranslations.length ; i++) {
Sentence temp = new Sentence();
temp.sentence = addStrings[i];
temp.translation = addTranslations[i];
sentences[i] = temp;
}
Otherwise you set sentence and translation continuously in the same object.
I am using an array adapter and to this am adding an array list of string s , the list is multi select , How can i get the values of list items clicked ?
my_contacts_list.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
ArrayAdapter<String> adapter=new ArrayAdapter<String>(this, android.R.layout.simple_list_item_multiple_choice,conts_list);
my_contacts_list.setAdapter(adapter);
I was trying to do this ,
SparseBooleanArray positions = my_contacts_list.getCheckedItemPositions();
int size=positions.size();
int i=0;
while(i <= size){
conts_list.get(positions.get(i));
i++;
}
But position.get(i) is an array list , how to retrieve the selected items then ?
SparseBooleanArray.get returns a boolean, but I believe you need to check it for each position in your list, e.g.
int len = listView.getCount();
SparseBooleanArray checked = listView.getCheckedItemPositions();
for (int i = 0; i < len; i++)
if (checked.get(i)) {
String item = cont_list.get(i);
/* do whatever you want with the checked item */
}
This API is a mess. Here is what works for me.
SparseBooleanArray checked = tags.getCheckedItemPositions();
for (int i = 0; i < checked.size(); i++) {
if(checked.valueAt(i)) {
Tag tag = (Tag) tags.getItemAtPosition(checked.keyAt(i));
Log.i("xxxx", i + " " + tag);
}
}
I believe the fastest way to get the info out of this SparseArray is to iterate over the keys (actually I'm fairly sure that the solutions above won't work in all cases). The ListView will enter a pair (index, true) into the SparseBooleanArray for every selected index.
So the code might look like this:
SparseBooleanArray checked = lv.getCheckedItemPositions();
int size = checked.size(); // number of name-value pairs in the array
for (int i = 0; i < size; i++) {
int key = checked.keyAt(i);
boolean value = checked.get(key);
if (value)
doSomethingWithSelectedIndex(key);
}
I think the Answer from Daren Robbins is Wrong, here is my answer:
ArrayList<String> ids = extras.getStringArrayList("commonids");
SparseBooleanArray checked = lv.getCheckedItemPositions();
for (int i = 0; i < checked.size(); i++) {
if(checked.get(i))
Log.i("CheckedItem", ids.get(checked.indexOfKey(i)));
}
Assume ids is an arraylist with the same size of the listview containing the ids of the items in the list view
The thing is you must iterate all the list view items but not checkedPositions.
Define the variables:
listView (The instance of you ListView)
names (the ArrayList you are )
saveCheckedName (save all checked name to this Arraylist)
SparseBooleanArray checkedPositions = listView.getCheckedItemPositions();
for (int i = 0; i < subjectListView.getCount(); i++) {
if (checkedPositions.get(i) == true) {
saveCheckedName.add(names.get(i));
}
}
Like so many other things, multi-select ListViews are a real problem in Android.
Instead of simply requesting the selected items as a List of Objects (dear Google, this is what we expect):
List selected_items = my_list_view.getSelectedItems();
we are forced to use this stupendously ridiculous API:
SparseBooleanArray checked = my_list_view.getCheckedItemPositions();
int num_selected = 0;
for(int i = 0; i < checked.size(); i++) {
if(checked.valueAt(i)) {
num_selected++;
int key = checked.keyAt(i);
boolean value = checked.get(key);
if (value) {
//
}
}
}
The horribly named SparseBooleanArray is populated by calling the even more horribly named getCheckedItemPositions() on the ListView. But instead of returning the positions of each selected/checked item in the list, it returns the position of every item in the list that WAS EVER touched, whether it is currently actually selected or not! Unbelievable, but true.
To calculate whether the item is ACTUALLY CURRENTLY checked, we are forced to test valueAt(i) for truthiness while looping through the 'was ever touched' array of items.
In addition to this madness, if we want to calculate the number of selected items, we appear to be forced to increment our own counter (e.g. num_selected).
With APIs like this one, it's little wonder developers are an angry lot!
I think another option is to just keep track of all of this yourself.
list.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> listView, View selectedItem,
int position, long itemId) {
//Keep a reference here, and toggle a global variable.
HOW I SOLVED THE ISSUE with a second ArrayList :
Created a second ArrayList instance
Updated that ArrayList instance with the UNCHECKED items
added it to the my listadapter
public void removeSelectedItems(){
updatedList = new ArrayList<String>(); //initialize the second ArrayList
int count = lv.getCount(); //number of my ListView items
SparseBooleanArray checkedItemPositions = getListView().getCheckedItemPositions();
for (int i=0;i < count;i++){
if(!checkedItemPositions.get(i))
updatedList.add(liveNames.get(i)); //liveNames is the current ArrayList
Log.e("TEST", liveNames.get(i));
}
adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_multiple_choice, updatedList);
setListAdapter(adapter);}
Hope it will be helpfull :)
Foo objectAtCheckedRow = null;
for (int i = 0; i < positions.size(); i++) { //positions.size() == 2
objectAtCheckedRow = adapter.getItem(positions.keyAt(i));
//Do something significant with object here
}
A couple things to understand
It's a key-value pair list.
The key is the index of a row, get it with positions.keyAt(i)
The value is whether the row at that index is checked or not(true or false), get it with positions.valueAt(i)
positions.get(i) returns the same boolean as .valueAt(i)
Careful not to get indexes mixed up. You do not need to(and should not) iterate over your whole list. Use int i to iterate over positions, but don't use i to get objects from your list
But in this specific case(listView.getCheckedPositions()) it only fills in true(checked rows), so you don't actually need to verify using .get(i) nor .valueAt(i)
Example:
Let's say you've checked the 5th and 8th items in the list(index 4 and 7), then positions.size() == 2 and i will be 0 and then 1
So when:
i == 0 then keyAt(i) == 4
i == 1 then keyAt(i) == 7
i == 0 OR i == 1 then valueAt(i) == true AND get(i) == true
FYI, Here is how Google did it:
Excerpted from http://mytracks.googlecode.com/hg/MyTracks/src/com/google/android/apps/mytracks/util/Api11Adapter.java
/**
* Gets the checked positions in a list view.
*
* #param list the list view
*/
private int[] getCheckedPositions(ListView list) {
SparseBooleanArray positions = list.getCheckedItemPositions();
ArrayList<Integer> arrayList = new ArrayList<Integer>();
for (int i = 0; i < positions.size(); i++) {
int key = positions.keyAt(i);
if (positions.valueAt(i)) {
arrayList.add(key);
}
}
int[] result = new int[arrayList.size()];
for (int i = 0; i < arrayList.size(); i++) {
result[i] = arrayList.get(i);
}
return result;
}
and here is my adapted version:
public static List<Integer> getAbsListViewCheckedItemPositions(AbsListView absListView) {
SparseBooleanArray checked = absListView.getCheckedItemPositions();
List<Integer> positions = new ArrayList<>();
int checkedSize = checked.size();
for (int i = 0; i < checkedSize; i++) {
if (checked.valueAt(i)) {
positions.add(checked.keyAt(i));
}
}
return positions;
}
We use this in our Android utility class. The generics help prevent compiler warnings, but you can remove them if your adapter returns multiple types.
public static <T> Collection<T> getCheckedItems(ListView listView) {
Collection<T> ret = new ArrayList();
SparseBooleanArray checkedItemPositions = listView.getCheckedItemPositions();
for (int i = 0; i < checkedItemPositions.size(); i++) {
if (checkedItemPositions.valueAt(i)) {
T item = (T) listView.getAdapter().getItem(checkedItemPositions.keyAt(i));
ret.add(item);
}
}
return ret;
}
Very simple, use below code
listViewRequests.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
AppCompatCheckedTextView checkBox = (AppCompatCheckedTextView) view;
if (checkBox.isChecked() == true){
Log.i("CHECK",checkBox.isChecked()+""+checkBox.getText().toString());
}
}
});
for(int i =0; i< listView.getAdapter().getCount(); i++){
if(listView.isItemChecked(i)){
listView.getAdapter().getItem(i); // item
}
}
should be used after setAdapter() method