Conversione stringa (String conversion)

You went looking in the wrong block pallette for the multiplication block.

Notice the math blocks are a slightly different color from the list blocks.

Th multiplication symbol is a little x.


This is the option to change the shape of a block between having sockets inside and sockets outside.

I created the rest...but I don't know how to proceed with the internal parameters

The generic option is for when you have a lot of the same component, like a chess board made of buttons, and you don't want to have to copy the same events from component to component. A single generic component can be used against all of them, reducing duplication of code.

It is for advanced coders who know how work with lists.

As you well know, I'm not an advanced programmer...and in any case I'm stuck at the crossroads about creating the mini-block in blue. Isn't it simpler that you just send the blocks (sunrise and sunset) to be able to insert them in the app? Thank you

The draggable blocks are in

sorry...I'm not very good...but by downloading I get an image it draggable? shouldn't be a .aia file

we did it ... I understood the difference between internal and external parameters

Dragging blocks

i fixed works....thanks for demonstrating draggability from an image to app inventor2....i learned a lot thanks to you....the only thing i didn't do is change the background when it is at sunset and at the same time changing the color of the characters from black to white. Conversely, when it is dawn, the night image must disappear and the color of the characters must pass from white to black
sky stellato

Do the formatted sunrise and sunset values look reasonable?
If not, it would be a waste of effort to compare the 1000*x values against Clock1.SystemTime.

Also, you should avoid black text on black background, or white text on white background.

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The formatted sunrise and sunset values seem reasonable... I tried entering the city of New York (about 6h10' time zone). The result is given in European time (Greenweek meridian) from which the 6 o'clock should be subtracted h 10'). With reference to the writings, as already indicated, when the sunset time arrives, the night image must appear and the characters from black must change to white. On the contrary, when it is dawn (sunrise) ... do you have any ideas?

So you really need an app to tell you if the sun is up?

Is it Weather for Cave Dwellers?

For the sake of learning a little logic, here's how to do it.

You will need two variables:

  • sunrise_ms
  • sunset_ms

After you get sunrise and seconds from the JSON response_content, fill those two variables from 1000 * sunrise and 1000 * sunset (which arrived as seconds.)

Use Clock1.SystemTime as your point of comparison against those two values, now that you are working in milliseconds.


  • sunrise_ms < Clock1.SystemTime
  • Clock1.SystemTime < sunset_ms)

then it is daytime
Else it is night.

The AND block is in the green logical blocks pallette.

Good evening. I have renounced the distinction between day and night (almost useless). Thanks for the information provided. Instead, I'm thinking about how to convert and display dates. For example 2023.08.20
display it, in the European format, as August 20, 2023 and likewise for all the other dates present in the forecasts. Is it possible?

Yes, date conversion can be done most easily with two blocks belonging to the Clock component (from the Sensors Drawer of the Designer):

  • Make an Instant
  • Format Date Time from an Instant

For your translation pleasure, here is a copy of the Java language datetime format table from SimpleDateFormat (Java Platform SE 7 )

Date and Time Patterns

Date and time formats are specified by date and time pattern strings. Within date and time pattern strings, unquoted letters from 'A' to 'Z' and from 'a' to 'z' are interpreted as pattern letters representing the components of a date or time string. Text can be quoted using single quotes (') to avoid interpretation. "''" represents a single quote. All other characters are not interpreted; they're simply copied into the output string during formatting or matched against the input string during parsing.

The following pattern letters are defined (all other characters from 'A' to 'Z' and from 'a' to 'z' are reserved):

Letter Date or Time Component Presentation Examples
G Era designator Text AD
y Year Year 1996; 96
Y Week year Year 2009; 09
M Month in year Month July; Jul; 07
w Week in year Number 27
W Week in month Number 2
D Day in year Number 189
d Day in month Number 10
F Day of week in month Number 2
E Day name in week Text Tuesday; Tue
u Day number of week (1 = Monday, ..., 7 = Sunday) Number 1
a Am/pm marker Text PM
H Hour in day (0-23) Number 0
k Hour in day (1-24) Number 24
K Hour in am/pm (0-11) Number 0
h Hour in am/pm (1-12) Number 12
m Minute in hour Number 30
s Second in minute Number 55
S Millisecond Number 978
z Time zone General time zone Pacific Standard Time; PST; GMT-08:00
Z Time zone RFC 822 time zone -0800
X Time zone ISO 8601 time zone -08; -0800; -08:00

Pattern letters are usually repeated, as their number determines the exact presentation:

  • Text: For formatting, if the number of pattern letters is 4 or more, the full form is used; otherwise a short or abbreviated form is used if available. For parsing, both forms are accepted, independent of the number of pattern letters.

  • Number: For formatting, the number of pattern letters is the minimum number of digits, and shorter numbers are zero-padded to this amount. For parsing, the number of pattern letters is ignored unless it's needed to separate two adjacent fields.

  • Year: If the formatter's Calendar is the Gregorian calendar, the following rules are applied.

    • For formatting, if the number of pattern letters is 2, the year is truncated to 2 digits; otherwise it is interpreted as a number.
    • For parsing, if the number of pattern letters is more than 2, the year is interpreted literally, regardless of the number of digits. So using the pattern "MM/dd/yyyy", "01/11/12" parses to Jan 11, 12 A.D.
    • For parsing with the abbreviated year pattern ("y" or "yy"), SimpleDateFormat must interpret the abbreviated year relative to some century. It does this by adjusting dates to be within 80 years before and 20 years after the time the SimpleDateFormat instance is created. For example, using a pattern of "MM/dd/yy" and a SimpleDateFormat instance created on Jan 1, 1997, the string "01/11/12" would be interpreted as Jan 11, 2012 while the string "05/04/64" would be interpreted as May 4, 1964. During parsing, only strings consisting of exactly two digits, as defined by Character.isDigit(char), will be parsed into the default century. Any other numeric string, such as a one digit string, a three or more digit string, or a two digit string that isn't all digits (for example, "-1"), is interpreted literally. So "01/02/3" or "01/02/003" are parsed, using the same pattern, as Jan 2, 3 AD. Likewise, "01/02/-3" is parsed as Jan 2, 4 BC.Otherwise, calendar system specific forms are applied. For both formatting and parsing, if the number of pattern letters is 4 or more, a calendar specific long form is used. Otherwise, a calendar specific short or abbreviated form is used.

If week year 'Y' is specified and the calendar doesn't support any week years, the calendar year ('y') is used instead. The support of week years can be tested with a call to getCalendar().isWeekDateSupported().

  • Month: If the number of pattern letters is 3 or more, the month is interpreted as text; otherwise, it is interpreted as a number.

  • General time zone: Time zones are interpreted as text if they have names. For time zones representing a GMT offset value, the following syntax is used:



Sign Hours


Minutes Sign: one of

+ -

Hours: Digit Digit Digit Minutes: Digit Digit Digit: one of

0 1 2 3 4 5 6 7 8 9

Hours must be between 0 and 23, and Minutes must be between 00 and 59. The format is locale independent and digits must be taken from the Basic Latin block of the Unicode standard.For parsing, RFC 822 time zones are also accepted.

  • RFC 822 time zone: For formatting, the RFC 822 4-digit time zone format is used:

RFC822TimeZone: Sign TwoDigitHours Minutes TwoDigitHours: Digit Digit

TwoDigitHours must be between 00 and 23. Other definitions are as for general time zones.For parsing, general time zones are also accepted.

  • ISO 8601 Time zone: The number of pattern letters designates the format for both formatting and parsing as follows:

ISO8601TimeZone: OneLetterISO8601TimeZone TwoLetterISO8601TimeZone ThreeLetterISO8601TimeZone OneLetterISO8601TimeZone: Sign TwoDigitHours


TwoLetterISO8601TimeZone: Sign TwoDigitHours Minutes


ThreeLetterISO8601TimeZone: Sign TwoDigitHours




Other definitions are as for general time zones or RFC 822 time zones.For formatting, if the offset value from GMT is 0, "Z" is produced. If the number of pattern letters is 1, any fraction of an hour is ignored. For example, if the pattern is "X" and the time zone is "GMT+05:30", "+05" is produced.For parsing, "Z" is parsed as the UTC time zone designator. General time zones are not accepted.If the number of pattern letters is 4 or more, IllegalArgumentException is thrown when constructing a SimpleDateFormat or applying a pattern.

SimpleDateFormat also supports localized date and time pattern strings. In these strings, the pattern letters described above may be replaced with other, locale dependent, pattern letters. SimpleDateFormat does not deal with the localization of text other than the pattern letters; that's up to the client of the class.


The following examples show how date and time patterns are interpreted in the U.S. locale. The given date and time are 2001-07-04 12:08:56 local time in the U.S. Pacific Time time zone.

Date and Time Pattern Result
"yyyy.MM.dd G 'at' HH:mm:ss z" 2001.07.04 AD at 12:08:56 PDT
"EEE, MMM d, ''yy" Wed, Jul 4, '01
"h:mm a" 12:08 PM
"hh 'o''clock' a, zzzz" 12 o'clock PM, Pacific Daylight Time
"K:mm a, z" 0:08 PM, PDT
"yyyyy.MMMMM.dd GGG hh:mm aaa" 02001.July.04 AD 12:08 PM
"EEE, d MMM yyyy HH:mm:ss Z" Wed, 4 Jul 2001 12:08:56 -0700
"yyMMddHHmmssZ" 010704120856-0700
"yyyy-MM-dd'T'HH:mm:ss.SSSZ" 2001-07-04T12:08:56.235-0700
"yyyy-MM-dd'T'HH:mm:ss.SSSXXX" 2001-07-04T12:08:56.235-07:00

Good morning Antonio. I'm proceeding to enter the air quality. It doesn't work for me... I can't get "co","no","no2" out of the json..... where did I go wrong? Thank you

Your path to the co is wrong.

It should be a list with three items

  • 'list'
  • 'components'
  • 'co'

You gave it a list with two items.

It's time to learn how to work with lists.

Look for the new tutorial in the tutorials section, by Saj

despite the list with 3 elements however I can't get the "co" out of the json

Unable to parse key as integer: components

Oops, I missed that [ after list.

It should be 4 items:

  • list
  • 1
  • components
  • co