Develop Reference

Creating a GridView based on user input using a for loop

I am trying to create a GridView that is based on the user input.
If the users input is x then the GridView shall show x elements. The problem is I don't want to have elements in GridView that starts with 0, as an Array in Java starts with index 0.
Here is a code snippet:
int numberOfTables=10; //let's say this is user input
String[] gridViewStrings = new String[numberOfTables];
for(int i =0; i<numberOfTables; i++){
gridViewStrings[i]="Table " +i;
The table descriptions should not start with 0, it should start with 1.
I tried to increment the array size by +1 but I get a BoundofException.
When you compile the code the output is :
Table0, Table1, Table2,...,Table9
The output I want is :
Table 1, Table2,...,Table10
How can I handle this ?

for(int i =1;i<numberOfTables; i++){ }
Try making your i to be 1. This might make the loop start at one not zero. and you moght not get an error
or you can try i+1

Google Sheets API v4 - How to get the last row with value?

How to get the last row with value in the new Google Sheets API v4 ?
i use this to get a range from a sheet:
mService.spreadsheets().values().get("ID_SHEET", "Sheet1!A2:B50").execute();
how to detect the last row with value in the sheet ?

You can set the range to "A2:D" and this would fetch as far as the last data row in your sheet.

I managed to get it by counting the total rows from current Sheets.
Then append the data to the next row.
rowcount = this.mService.spreadsheets().values().get(spreadsheetId, range).execute().getValues().size()

Rather than retrieving all the rows into memory just to get the values in the last row, you can use the append API to append an empty table to the end of the sheet, and then parse the range that comes back in the response. You can then use the index of the last row to request just the data you want.
This example is in Python:
#empty table
table = {
'majorDimension': 'ROWS',
'values': []
}
# append the empty table
request = service.spreadsheets().values().append(
spreadsheetId=SPREADSHEET_ID,
range=RANGE_NAME,
valueInputOption='USER_ENTERED',
insertDataOption='INSERT_ROWS',
body=table)
result = request.execute()
# get last row index
p = re.compile('^.*![A-Z]+\d+:[A-Z]+(\d+)$')
match = p.match(result['tableRange'])
lastrow = match.group(1)
# lookup the data on the last row
result = service.spreadsheets().values().get(
spreadsheetId=SPREADSHEET_ID,
range=f'Sheetname!A{lastrow}:ZZ{lastrow}'
).execute()
print(result)

😢 Google Sheets API v4 does not have a response that help you to get the index of the last written row in a sheet (row that all cells below it are empty). Sadly, you'll have to workaround and fetch all sheet rows' into memory (I urge you to comment if I'm mistaken)
Example:
spreadsheet_id = '1TfWKWaWypbq7wc4gbe2eavRBjzuOcpAD028CH4esgKw'
range = 'Sheet1!A:Z'
rows = service.spreadsheets().values().get(spreadsheetId=spreadsheet_id, range=range).execute().get('values', [])
last_row = rows[-1] if rows else None
last_row_id = len(rows)
print(last_row_id, last_row)
Output:
13 ['this', 'is ', 'my', 'last', 'row']
💡 If you wish to append more rows to the last row, see this

You don't need to. Set a huge range (for example A2:D5000) to guarantee that all your rows will be located in it. I don't know if it has some further impact, may be increased memory consumption or something, but for now it's OK.
private List<String> getDataFromApi() throws IOException {
String spreadsheetId = "1BxiMVs0XRA5nFMdKvBdBZjgmUUqptlbs74OgvE2upms";
String range = "A2:D5000";
List<String> results = new ArrayList<String>();
ValueRange response = this.mService.spreadsheets().values()
.get(spreadsheetId, range)
.execute();
List<List<Object>> values = response.getValues();
if (values != null) {
results.add("Name, Major");
for (List row : values) {
results.add(row.get(0) + ", " + row.get(3));
}
}
return results;
}
Look at the loop for (List row : values). If you have two rows in your table you will get two elements in values list.

Have a cell somewhere that doesn't interfere with your datarange with =COUNTA(A:A) formula and get that value.
In your case
=MAX(COUNTA(A:A50),COUNTA(B:B50))
?
If there could be empty cells inbetween the formula would be a little more tricky but I believe it saves you some memories.

2022 Update
I I don’t know if this will be relevant for someone in 2022, but now you can do it differently.
You can just set next value as range :
const column = "A"
const startIndex = 2
const range = column + startIndex + ":" + column
In resolve you get all data in column and range with last index.
I tested it on js and php

Following Mark B's answer, I created a function that performs a dummy append and then extracts the last row info from the dummy append's response.
def get_last_row_with_data(service, value_input_option="USER_ENTERED"):
last_row_with_data = '1'
try:
dummy_request_append = service.spreadsheets().values().append(
spreadsheetId='<spreadsheet id>',
range="{0}!A:{1}".format('Tab Name', 'ZZZ'),
valueInputOption='USER_ENTERED',
includeValuesInResponse=True,
responseValueRenderOption='UNFORMATTED_VALUE',
body={
"values": [['']]
}
).execute()
a1_range = dummy_request_append.get('updates', {}).get('updatedRange', 'dummy_tab!a1')
bottom_right_range = a1_range.split('!')[1]
number_chars = [i for i in list(bottom_right_range) if i.isdigit()]
last_row_with_data = ''.join(number_chars)
except Exception as e:
last_row_with_data = '1'
return last_row_with_data

Fragment crash: IndexOutOfBoundsException: Invalid index x, size is x after updating my database [duplicate]

When I do
ArrayList<Integer> arr = new ArrayList<Integer>(10);
arr.set(0, 1);
Java gives me
Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
at java.util.ArrayList.rangeCheck(Unknown Source)
at java.util.ArrayList.set(Unknown Source)
at HelloWorld.main(HelloWorld.java:13)
Is there an easy way I can pre-reserve the size of ArrayList and then use the indices immediately, just like arrays?

How about this:
ArrayList<Integer> arr = new ArrayList<Integer>(Collections.nCopies(10, 0));
This will initialize arr with 10 zero's. Then you can feel free to use the indexes immediately.

Here's the source from ArrayList:
The constructor:
public ArrayList(int initialCapacity)
{
super();
if (initialCapacity < 0)
throw new IllegalArgumentException("Illegal Capacity: "+ initialCapacity);
this.elementData = new Object[initialCapacity];
}
You called set(int, E):
public E set(int index, E element)
{
rangeCheck(index);
E oldValue = elementData(index);
elementData[index] = element;
return oldValue;
}
Set calls rangeCheck(int):
private void rangeCheck(int index)
{
if (index >= size) {
throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
}
}
It may be subtle, but when you called the constructor, despite initializing an Object[], you did not initialize size. Hence, from rangeCheck, you get the IndexOutOfBoundsException, since size is 0. Instead of using set(int, E), you can use add(E e) (adds e of type E to the end of the list, in your case: add(1)) and this won't occur. Or, if it suits you, you could initialize all elements to 0 as suggested in another answer.

I believe the issue here is that although you have suggested the allocated space of entries in the Array, you have not actually created entries.
What does arr.size() return?
I think you need to use the add(T) method instead.

Programming aside, what you are trying to do here is illogical.
Imagine an empty egg carton with space for ten eggs. That is more or less what you have created. Then you tell a super-precise-and-annoying-which-does-exactly-what-you-tell-him robot to replace the 0th egg with another egg. The robot reports an error. Why? He can't replace the 0th egg, because there is no egg there! There is a space reserved for 10 eggs, but there are really no eggs inside!

You could use arr.add(1), which will add 1 in the first empty cell, i.e. the 0-indexed one.
Or you could create your own list:
public static class PresetArrayList<E> extends ArrayList<E> {
private static final long serialVersionUID = 1L;
public PresetArrayList(int initialCapacity) {
super(initialCapacity);
addAll(Collections.nCopies(initialCapacity, (E) null));
}
}
Then:
List<Integer> list = new PresetArrayList<Integer>(5);
list.set(3, 1);
System.out.println(list);
Prints:
[null, null, null, 1, null]

This is not an Java-specific answer but an data structure answer.
You are confusing the Capacity concept with the Count (or Size) one.
Capacity is when you tell the list to reserve/preallocate a number of slots in advance (in this ArrayList case, you are saying to it create an array of 10 positions) in its' internal storage. When this happens, the list still does not have any items.
Size (or Count) is the quantity of items the list really have. In your code, you really doesn't added any item - so the IndexOutOfBoundException is deserved.

While you can't do what you want with arraylist, there is another option: Arrays.asList()

Capacity is used to prepare ArrayLists for expansion. Take the loop
List<Integer> list = new ArrayList<>();
for(final int i = 0; i < 1024; ++i) {
list.add(i);
}
list starts off with a capacity of 10. Therefore it holds a new Integer[10] inside. As the loop adds to the list, the integers are added to that array. When the array is filled and another number is added, a new array is allocated twice the size of the old one, and the old values are copied to the new ones. Adding an item is O(1) at best, and O(N) at worst. But adding N items will take about 2*1024 individual assignments: amortized linear time.
Capacity isn't size. If you haven't added to the array list yet, the size will be zero, and attempting to write into the 3rd element will fail.

Getting error Invalid Index

I am trying to display a list from current year plus five year in a Spinner item. But getting error java.lang.IndexOutOfBoundsException: Invalid index 2014, size is 0
I used this code,
ArrayList<String> years=new ArrayList<String>();
Calendar cal=Calendar.getInstance();
int curYear= cal.get(Calendar.YEAR);
for(int i=0;i<6;i++)
{
years.add(curYear+i, null);
}
Spinner spnYear= (Spinner) findViewById(R.id.spnYear);
ArrayAdapter<String> adapter=new ArrayAdapter<String>(this, android.R.layout.simple_dropdown_item_1line, years);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spnYear.setAdapter(adapter);
Please help.
Thanks.

When you use add() with two parameters, the first is the index you would like to add it at. You'll want to just call years.add(String.valueOf(currYear + 1)). I've also added the String.valueOf() around the item you're adding, because you have an ArrayList<String>

It's how you're adding things to your ArrayList. For one, you're trying to add an int curYear + i to an ArrayList<String>. That won't work. Second you're adding them in such a way that you're not actually passing an object to the list. The version of add you're using add(int index, E object) takes the index as its first argument - not what you want to add to the list. Your second argument, which is what you actually want to add, is null. That explains why you're getting list size of 0. You should just add your values normally and know that index 0, 1, 2, 3, 4 will be the next 5 years.

here is your issue
for(int i=0;i<6;i++) {
years.add(curYear+i, null);
}
you are using the add method that takes a first paramter the index and as second the object. The documentation states that it throws
IndexOutOfBoundsException - if the index is out of range (index < 0 || index > size()).
At the first iteration size() returns 0, and you are try to put the element at position 2014
Change it in
for(int i=0;i<6;i++) {
years.add(String.valueOf(curYear+i));
}

java.lang.IndexOutOfBoundsException: Invalid index 2, size is 2

Scenario:-
I have two ArrayList
list contains images
postList contains position of selected images
now when ever i am selecting the images and press delete menu ,it should delete the selected images .
when i am running the code in debug ,its working fine and give the desire output.
but when i am running it normal mode ,its crashing and giving above exception.
if (posList.size() > 0)
{
Toast.makeText(getBaseContext(), "i value" +posList.size(),
Toast.LENGTH_SHORT).show();
for (int i = 0; i < posList.size(); i++)
appAdp.list.remove(appAdp.list.get(posList.get(i)));
appAdp.notifyDataSetChanged();
posList.clear();
Toast.makeText(getBaseContext(), "You deleted selected items",
Toast.LENGTH_SHORT).show();
}
return true;
postList values here
#Override
public void onItemCheckedStateChanged(ActionMode mode, int position, long id,
boolean checked) {
posList.add(position);
error showing here
appAdp.list.remove(appAdp.list.get(posList.get(i)));
logcat:-
java.lang.IndexOutOfBoundsException: Invalid index 2, size is 2
at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:251)
at java.util.ArrayList.get(ArrayList.java:304)
why its behaving like this ,not getting any clue.
Thanks for any help.

You are trying to perform operation on Same ArrayList because of that when ever you are remove elemnt from the ArrayList then its size will reduce so, You'll get ArrayIndexoutofBoundsException.
i.e when you remove item from the appAdp.list , then the size of the appAdp.list will also change
consider if your list has originally 3 elemnts.
you have the position in your posList 0,2
then when you remove item from the 0 item from appAdp.list, its size will become 2 for the next time when you try to remove item at position 2, you will get AIOBE
Solution:
Save all items that needs to be removed in separate List and the use removeAll(list) method to remove items from your appAdp.list
Example:
ArrayList<yourappListtype> templist=new ArrayList<yourappListtype>();
for (int i = 0; i < posList.size(); i++)
templist.add(appAdp.list.get(posList.get(i)));
And then
appAdp.list.removeAll(templist);

try this code,
postList.remove(position);
then,
notifyItemRangeChanged(positon,postList.size());

Before you change the data source of adapter, you can call adapter's notifyDataSetInvalidated() function to make the origin data source invalid, then call adapter's notifyDataSetChanged() after finish changing the data source.

remember that index are starting from zero. I think you when get position it is +1 higher than index of array, so you get out of bounds exception

The error is Invalid index 2, size is 2
Possible issue is your posList.size()=2 where as appAdp.list.size()<2
Make sure that your appAdp.list has more than two entries.
if (posList.size() >0)
i=appAdp.list.size();
while(i<=posList.size() && i<=appAdp.list.size())
{
appAdp.list.remove(appAdp.list.get(posList.get(i)));
i--;
}

The basic meaning of the exception java.lang.IndexOutOfBoundsException: Invalid index x, size is y where x and y are the index position and size respectively means you are attempting to get value at a position that does not exist. Take for example an ArrayList with a size 2, typically you would want to get value(s) by specifying position index which in this case the valid position would either be 0 or 1 and end up specifying a position 2 (index 2 does not exist). I believe understanding basic meaning of Java errors will save you a lot of valuable time in your development.

just use break command at the end of for loop, like this:
fun deleteUser(userID: Int) {
for(i in 0 until usersList.size) {
if (usersList[i].id == userID) {
usersList.removeAt(i)
notifyItemRemoved(i)
break
}
}
}