How to add items to ListView1:jListView?
lazarus / 43-Android

----------------------------------------------------------------------
Bandy · 2025-08-08 08:13

Hello.

I want code to add items to ListView1:jListView and show them in
reversed order, meaning the last added item to be displayed on top of
(or first on) the list?

How can I do it?

----------------------------------------------------------------------
Bandy · 2025-08-10 09:14

Please guys... anyone can help?

----------------------------------------------------------------------
cdbc · 2025-08-10 10:06

Hi
Look at the examples, demoes & the source-code provided and think a
little bit... Don't be so helpless.
Regards Benny

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Bandy · 2025-08-10 11:40

I'm trying to add items to ListView1 from a text file when the app
starts (OnCreate event) with the following code:

procedure TAndroidModule1.AndroidModule1Create(Sender: TObject);
var f:TextFile;
    a:string;
begin
AssignFile(f, '/Spațiu de stocare intern/Fisiere/Raspunsuri.txt');
Reset(f);
while not(eof(f)) do
  begin
        with ListView1.Items do
          begin
            readln(f,a);
            Add(a);

            readln(f,a);
            Add(a);

            readln(f,a);
            Add(a);
          end;

        repeat
         readln(f,a);
        until a=' ';

  end;
CloseFile(f);

end;

/Spațiu de stocare intern/Fisiere/Raspunsuri.txt translates from
romanian language to english language to /Internal
Storage/Files/Answers.txt. This is where my text file is located. My
smartphone has Android 13 in romanian language.

The app starts, shows the Android icon and the exits, doesn't do
anything. What's wrong, please?

----------------------------------------------------------------------
Aruna · 2025-08-10 12:00

Quote from: Bandy on August 10, 2025, 01:40:46 pmI'm trying to add
items to ListView1 from a text file when the app starts (OnCreate
event) with the following code:
<snip>
The app starts, shows the Android icon and the exits, doesn't do
anything. What's wrong, please?
Right now your code uses Add(a), which always appends to the bottom of
the ListView.To make new entries appear at the top, you need to use
Insert(0) instead.
Also, TListView.Items.Insert(0) doesn’t take the text directly, you
must assign it to .Caption after creating the item.

Here’s your modified code so that every read line is inserted at the
top:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TAndroidModule1.AndroidModule1Create(Sender: TObject);var  f:
TextFile;  a: string;  Item: TListItem;begin  AssignFile(f, '/Spațiu
de stocare intern/Fisiere/Raspunsuri.txt');  Reset(f);  while not
EOF(f) do  begin    // First line    ReadLn(f, a);    Item :=
ListView1.Items.Insert(0);    Item.Caption := a;     // Second line  
ReadLn(f, a);    Item := ListView1.Items.Insert(0);    Item.Caption :=
a;     // Third line    ReadLn(f, a);    Item :=
ListView1.Items.Insert(0);    Item.Caption := a;     // Skip lines
until a single space ' ' is found    repeat      ReadLn(f, a);   
until a = ' ';  end;  CloseFile(f);end; 
EDIT: I have attached a minimal working sample in the zip.

----------------------------------------------------------------------
Bandy · 2025-08-10 14:22

I get errors when running the above code in LAMW4Windows 3.8. These
are the messages:

Messages, Hints: 2
Verbose: Selected chip architecture: arm64-v8a
Verbose: Taking libraries from folder:
C:\Users\Andy\Desktop\Android\Prognoza\libs\arm64-v8a
Verbose: Found library: libcontrols.so
Note: Duplicate unit "controls" in "controls", orphaned ppu
"C:\Users\Andy\Desktop\Android\Prognoza\obj\controls\controls.o"
Note: Duplicate unit "controls" in "LCLBase 3.8", ppu="C:\lamw_manager
\LAMW\LAMW4Windows\lazarus_trunk\lcl\units\aarch64-
android\controls.ppu", source="C:\lamw_manager\LAMW\LAMW4Windows\lazar
us_trunk\lcl\controls.pp"
Project: Executing command before: Success
before build...
Compile Project, OS: android, CPU: aarch64, Target:
C:\Users\Andy\Desktop\Android\Prognoza\libs\arm64-v8a\libcontrols.so:
Exit code 1, Errors: 11, Hints: 1
unit1.pas(21,61) Hint: Parameter "intentData" not used
unit1.pas(63,9) Error: Identifier not found "TListItem"
unit1.pas(63,18) Error: Error in type definition
unit1.pas(71,38) Error: Wrong number of parameters specified for call
to "Insert"
classesh.inc(739,15) Error: Found declaration: Insert(LongInt;const
AnsiString);
unit1.pas(72,10) Error: Illegal qualifier
unit1.pas(76,38) Error: Wrong number of parameters specified for call
to "Insert"
classesh.inc(739,15) Error: Found declaration: Insert(LongInt;const
AnsiString);
unit1.pas(77,10) Error: Illegal qualifier
unit1.pas(81,38) Error: Wrong number of parameters specified for call
to "Insert"
classesh.inc(739,15) Error: Found declaration: Insert(LongInt;const
AnsiString);
unit1.pas(82,10) Error: Illegal qualifier
Exception, Errors: 1
Fatal: [Exception] Failed: Cannot build project

Is the above code for Android app development? I need code for Android
app developement.

----------------------------------------------------------------------
dseligo · 2025-08-10 22:28

Quote from: Bandy on August 10, 2025, 01:40:46 pmAssignFile(f,
'/Spațiu de stocare intern/Fisiere/Raspunsuri.txt');

Is this path inside your app?
If not, you could have issues with permission to access file.

I would try two things:
1. Instead of reading a file, try to add just couple of test strings.
2. Try to first create test file in app's storage, and write couple of
test lines to that file. After that read that file and see if your
code works.

----------------------------------------------------------------------
Aruna · 2025-08-11 02:21

Quote from: Bandy on August 10, 2025, 04:22:59 pmIs the above code for
Android app development? I need code for Android app developement.
  
My apologies, what I sent is Lazarus (desktop) not android.

----------------------------------------------------------------------
Bandy · 2025-08-11 07:32

For dseligo:

AssignFile(f, '/Spațiu de stocare intern/Fisiere/Raspunsuri.txt'); is
a line inside my app code. The file '/Spațiu de stocare
intern/Fisiere/Raspunsuri.txt' is already created and already contains
text/strings, I'm just trying to read it. I don't have a working code
for this.

----------------------------------------------------------------------
dseligo · 2025-08-11 09:04

Quote from: Bandy on August 11, 2025, 09:32:20 amFor dseligo:

AssignFile(f, '/Spațiu de stocare intern/Fisiere/Raspunsuri.txt'); is
a line inside my app code. The file '/Spațiu de stocare
intern/Fisiere/Raspunsuri.txt' is already created and already contains
text/strings, I'm just trying to read it. I don't have a working code
for this.

Where is this file created? Did you create it in your app and is it
located in internal storage of your app? If it is in external storage
you'll need permissions to access file. That's why I suggested to
steps to test if that is a case.

----------------------------------------------------------------------
Bandy · 2025-08-11 11:59

Quote from: dseligo on August 11, 2025, 11:04:30 amQuote from: Bandy
on August 11, 2025, 09:32:20 amFor dseligo:

AssignFile(f, '/Spațiu de stocare intern/Fisiere/Raspunsuri.txt'); is
a line inside my app code. The file '/Spațiu de stocare
intern/Fisiere/Raspunsuri.txt' is already created and already contains
text/strings, I'm just trying to read it. I don't have a working code
for this.

Where is this file created? Did you create it in your app and is it
located in internal storage of your app? If it is in external storage
you'll need permissions to access file. That's why I suggested to
steps to test if that is a case.
The file is already created by me, I mean already written by me using
the keyboard. /Spațiu de stocare intern/Fisiere/Raspunsuri.txt
translates from romanian language to english language to /Internal
Storage/Files/Answers.txt. Here is located (stored) the file, in
/Internal Storage/Files/Answers.txt. My smartphone has Android 13 in
romanian language.

Please, I need working code in LAMW4Windows 3.8 to read the file and
to view it in ListView1. I hope now it's clear.

----------------------------------------------------------------------
dseligo · 2025-08-11 20:35

Quote from: Bandy on August 11, 2025, 01:59:27 pmQuote from: dseligo
on August 11, 2025, 11:04:30 amQuote from: Bandy on August 11, 2025,
09:32:20 amFor dseligo:

AssignFile(f, '/Spațiu de stocare intern/Fisiere/Raspunsuri.txt'); is
a line inside my app code. The file '/Spațiu de stocare
intern/Fisiere/Raspunsuri.txt' is already created and already contains
text/strings, I'm just trying to read it. I don't have a working code
for this.

Where is this file created? Did you create it in your app and is it
located in internal storage of your app? If it is in external storage
you'll need permissions to access file. That's why I suggested to
steps to test if that is a case.
The file is already created by me, I mean already written by me using
the keyboard. /Spațiu de stocare intern/Fisiere/Raspunsuri.txt
translates from romanian language to english language to /Internal
Storage/Files/Answers.txt. Here is located (stored) the file, in
/Internal Storage/Files/Answers.txt. My smartphone has Android 13 in
romanian language.

Please, I need working code in LAMW4Windows 3.8 to read the file and
to view it in ListView1. I hope now it's clear.

It's not clear. Did you create file within your app? Or is it
somewhere else in your phone (external storage) and not within your
application? If it's in external storage it won't work like that. Look
here: https://developer.android.com/training/data-storage

Test two things from reply #6 and post results here.

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nicelybrewed · 2025-08-11 22:42

@Bandy
Not sure if this is what you're after, but this is a simple add string
to a jlistview, loading in a reversed stringlist. Have a look at
main.pas attached.
You can tweak it how you want it, I'm saving a file to the apps own
internal storage using dirDownloads (/Internal
storage/Android/data/org.lamw.bandy/files/Download).
I'm on Android 14, but expect it should be OK back to Android 10 at
least, possibly further, it uses a jListView, jEditText and jButton.

----------------------------------------------------------------------
jmpessoa · 2025-08-11 22:44

Hi, All!

For LAMW,  don't use the event "OnCreate". Ex.:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TAndroidModule1.AndroidModule1Create(Sender: TObject); to call Android
stuff.... (only to call pure pascal stuff...)

For LAMW you need handle "OnJNIPrompt" event to call android API
stuff....!

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Bandy · 2025-08-13 07:37

Guys, I want to make a confession: I have little or no Android
development knowledge and I have some Windows development knowledge; I
have an Windows app made in Lazarus 4.0 for Windows that I love very
much; I want to translate this Windows app code to build and run
(Ctrl+F1) it in LAMW4Windows 3.8 and on my Android smartphone. So I'm
giving you parts of the Lazarus 4.0 for Windows code and please,
please, please give me the translation to LAMW4Windows 3.8 code.

This is part of the Lazarus 4.0 for Windows code:

procedure TForm1.FormCreate(Sender: TObject);
var f:TextFile;
     a:string;
begin
AssignFile(f, 'Raspunsuri.txt');
Reset(f);                     
while not(eof(f)) do
  begin
        with ListView1.Items.Insert(0) do
          begin
            readln(f,a);
            Caption:=a;

            readln(f,a);
            SubItems.Add(a);

            readln(f,a);
            SubItems.Add(a);
          end;

        repeat
         readln(f,a);
        until a=' ';

  end;
CloseFile(f);
end;

This code runs when the OnCreate event is triggered in Windows,
meaning that this code execute automatically when the Windows app is
started, without pressing any buttons or do any action. Also in
Android, the code should execute automatically when the Android app is
started, without pressing any buttons or do any action.

----------------------------------------------------------------------
cdbc · 2025-08-13 10:11

Hi
QuoteFor LAMW you need handle "OnJNIPrompt" event to call android API
stuff....!What, in the above is NOT clear to you?!?
/bc

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nicelybrewed · 2025-08-16 09:56

@Bandy
Check my code in Reply #12, as mentioned by others, use OnJNIPrompt
for startup code.

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Bandy · 2025-08-18 13:09

@nicelybrewed: Please read my post from Reply #14 and translate the
code for me.

@everyone: Where do I find documentation about OnJNIPrompt event?

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Bandy · 2025-08-21 07:09

Anyone... please help me.

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mirce.vladimirov · 2025-08-21 11:38

Quote from: Bandy on August 08, 2025, 10:13:19 amHello.

I want code to add items to ListView1:jListView and show them in
reversed order, meaning the last added item to be displayed on top of
(or first on) the list?

How can I do it?

This is my code, i used Zeos Query which you can order as you like :
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i    
 jListView1.Clear;     ZeosQuery1.first;      while not ZeosQuery1.EOF
do begin             jListView1.Add(           
 ZeosQuery1.FieldByName('datafield1').AsString + '|' + // <<- '|' is
used as a column separator              'Second field:' +
FormatFloat('#,##0.00', ZeosQuery1.FieldByName('datafield2').asfloat)
+ '|' +             'Third field:' +
 ZeosQuery1.FieldByName('datafield3').AsString)            );        
   ZeosQuery1.Next;     end;
EDIT: this is used in my code on show , and i am using that on
jbuttonclick too

more EDIT: of course , if you dont use Zeos Query but a text file
istead, you first need to load that file in a TString List and order
it, and then write to jListView

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i var  
MyFile: TStringList;begin  MyFile:=TStringList.Create; 
MyFile.LoadFromFile('TheRealFile.txt');     MyFile.Sort; //do
everything you need to   MyFile.free;  // <<-- do this after you do
all the processing the data contained in itend; 
and then iterate thru the items of the TSTringlist and put each line
in the jListView as described above.

I hope that helped.

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dseligo · 2025-08-25 12:25

I created test project which reads file and show content in ListView.

These are steps to recreate it:
- create new project 'LAMW [GUI] Android Module' and save it
- put jButton and jListView on a form and set their layout and
positions
- in Button1 click method put following code:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TAndroidModule1.Button1Click(Sender: TObject);var f: Textfile;    i:
Integer;begin  AssignFile(f, GetFilePath(fpathData) + '\test.dat'); 
Rewrite(f);  WriteLn(f, 'Created: ' + FormatDateTime('yyyy-mm-dd
hh:nn:ss ', Now));  For i := 1 to 10 do    WriteLn(f, 'Line ' +
IntToStr(i) + '.');  CloseFile(f);end;- in OnJNIPrompt method of the
form put following code:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TAndroidModule1.AndroidModule1JNIPrompt(Sender: TObject);var f:
Textfile;    s: String;begin  ListView1.Clear;  If
FileExists(GetFilePath(fpathData) + '\test.dat') then  begin   
AssignFile(f, GetFilePath(fpathData) + '\test.dat');    Reset(f);   
While not Eof(f) do    begin      ReadLn(f, s);     
ListView1.Add(s);    end;    CloseFile(f);  end  else   
ListView1.Add('File doesn''t exists.');end;
After first run there is no file and 'File doesn't exists' message is
displayed in ListView. Press Button1 and restart app. Now you should
see rows from file in ListView.
I attached screenshots from my phone (first run and 2nd run after
pressing Button1).
I also attached content of JNI directory.

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Bandy · 2025-08-26 08:29

Quote from: dseligo on August 25, 2025, 02:25:29 pmI created test
project which reads file and show content in ListView.

These are steps to recreate it:
- create new project 'LAMW [GUI] Android Module' and save it
- put jButton and jListView on a form and set their layout and
positions
- in Button1 click method put following code:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TAndroidModule1.Button1Click(Sender: TObject);var f: Textfile;    i:
Integer;begin  AssignFile(f, GetFilePath(fpathData) + '\test.dat'); 
Rewrite(f);  WriteLn(f, 'Created: ' + FormatDateTime('yyyy-mm-dd
hh:nn:ss ', Now));  For i := 1 to 10 do    WriteLn(f, 'Line ' +
IntToStr(i) + '.');  CloseFile(f);end;- in OnJNIPrompt method of the
form put following code:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TAndroidModule1.AndroidModule1JNIPrompt(Sender: TObject);var f:
Textfile;    s: String;begin  ListView1.Clear;  If
FileExists(GetFilePath(fpathData) + '\test.dat') then  begin   
AssignFile(f, GetFilePath(fpathData) + '\test.dat');    Reset(f);   
While not Eof(f) do    begin      ReadLn(f, s);     
ListView1.Add(s);    end;    CloseFile(f);  end  else   
ListView1.Add('File doesn''t exists.');end;
After first run there is no file and 'File doesn't exists' message is
displayed in ListView. Press Button1 and restart app. Now you should
see rows from file in ListView.
I attached screenshots from my phone (first run and 2nd run after
pressing Button1).
I also attached content of JNI directory.
Thank you, dseligo! It works!

1) Now, please modify the code to add the lines in reversed order
(last added line to be shown first in ListView).

2) After that, please make me understand how to create the file
test.dat in other path (location) different from
GetFilePath(fpathData) + '\test.dat', let's say on the root of SdCard
(something like this SdCard+'\test.dat', and then read test.dat from
this different path (location).

----------------------------------------------------------------------
dseligo · 2025-08-26 11:43

Quote from: Bandy on August 26, 2025, 10:29:04 am1) Now, please modify
the code to add the lines in reversed order (last added line to be
shown first in ListView).

This is easy. Just change line where is ListView1.Add(s); to:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
ListView1.Insert(0, s);
Quote2) After that, please make me understand how to create the file
test.dat in other path (location) different from
GetFilePath(fpathData) + '\test.dat', let's say on the root of SdCard
(something like this SdCard+'\test.dat', and then read test.dat from
this different path (location).

This is a bit trickier. Problem is that Android limits access to data
outside your app for security. I use RequestOpenFile procedure and
then copy bytes from chosen file to local app storage. There you can
read/write files without restriction. There are (probably) other ways
to do it, but this approach is enough for me.

To do it, put component jIntentManager to your form. Add following
constants somewhere above methods that use them:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i const
cRCOpenFile = 1001;      cFileName = '\test.dat';
Change Button1 click method to:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TAndroidModule1.Button1Click(Sender: TObject);begin 
RequestOpenFile(GetEnvironmentDirectoryPath(dirDownloads),
'text/plain', cRCOpenFile); // or: dirDocumentsend;
Put following code in OnActivityResult method of the form:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TAndroidModule1.AndroidModule1ActivityResult(Sender: TObject;
requestCode: integer;  resultCode: TAndroidResult; intentData:
jObject);var Uri: jObject;    BytesFromUri: TDynArrayOfJByte;    fs:
TFileStream;begin  If (resultCode = RESULT_OK) and (requestCode =
cRCOpenFile) then  begin    Uri :=
IntentManager1.GetDataUri(intentData);     // write file from Uri to
app data directory (where you can read/write as usual)    BytesFromUri
:= LoadBytesFromUri(Uri);    fs :=
TFileStream.Create(GetFilePath(fpathData) + cFileName, fmCreate);   
try      fs.Seek(0, soFromBeginning);      fs.Write(BytesFromUri[0],
Length(BytesFromUri));    finally      fs.Free;     
SetLength(BytesFromUri, 0);    end;  end;end;
When you press Button1 you'll get to choose file. After choosing file
is copied to your app data directory (so you don't have to choose file
each time).

I attached files from project.

----------------------------------------------------------------------
Bandy · 2025-08-27 08:05

@dseligo:

1) Please explain every line of the code from OnActivityResult method
of the form.

2) Please where do I find information/documentation about
RequestOpenFile, GetEnvironmentDirectoryPath, dirDownloads, Uri,
IntentManager, OnActivityResult event of the form, OnJNIPrompt event
of the form, etc.?

----------------------------------------------------------------------
dseligo · 2025-08-28 10:16

Quote from: Bandy on August 27, 2025, 10:05:19 am1) Please explain
every line of the code from OnActivityResult method of the form.

Method OnActivityResult is called after some activity ends (activity
that you started with RequestOpenFile in this case). More here: https:
//developer.android.com/reference/android/app/Activity#onActivityResul
t(int,%20int,%20android.content.Intent)

Checks if this is result for calling RequestOpenFile (because you can
call various activities and get results from them): Code: Pascal
 [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i If
(resultCode = RESULT_OK) and (requestCode = cRCOpenFile) then
Get URI reference to data in file (https://developer.android.com/refer
ence/android/content/Intent#getData()): Code: Pascal
 [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i Uri :=
IntentManager1.GetDataUri(intentData);
Read bytes from file to an array: Code: Pascal
 [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
BytesFromUri := LoadBytesFromUri(Uri);
The rest is standard Free Pascal, it writes data from array to file
stream, to create file in scope of your app so you can read contect
directly.

Quote2) Please where do I find information/documentation about
RequestOpenFile, GetEnvironmentDirectoryPath, dirDownloads, Uri,
IntentManager, OnActivityResult event of the form, OnJNIPrompt event
of the form, etc.?

Try and examine examples in your LAMW Lazarus installation directory
(..\fpc-lazarus\ccr\lamw\demos\GUI), such as:
AppPublicFoldersAccessDemo1, lots of AppIntentDemo... examples,
AppTest1, ...
You can (or must?) also read Android documentation (I gave you couple
of links above) and search through LAMW source code.