Android Question Write large files (multiple photos)

heldenssjoerd · Jun 3, 2025

Hello,

In the app we need to save and upload a large (xml) file. It works as long as the file (created with XMLBuilder) stays within certain limits. However when saving the xml with 10+ large photos (base64) then the error below occurs.
Largeheap is already activated in the manifest.

B4X:

File.WriteString(Map_Wachtrij, sFilename, x.asString) 'x =XMLBuilder and writestring triggers an error below

B4X:

java.lang.OutOfMemoryError: Failed to allocate a 226207176 byte allocation with 25165824 free bytes and 70MB until OOM, max allowed footprint 488170160, growth limit 536870912

Any thoughts?

Erel · Jun 8, 2025

Better to post the full stack trace.

File.WriteString converts the full string to an array of bytes. You can save some memory by doing it in chunks and writing the bytes with OutputStream.

heldenssjoerd · Jun 16, 2025

used to write:

B4X:

Dim x As XMLBuilder

'fill x with photo's and other tags

File.WriteString(Map_JDS, File_PDA,x.asString)

error:

B4X:

java.lang.OutOfMemoryError: Failed to allocate a 123122680 byte allocation with 25165824 free bytes and 106MB until OOM, max allowed footprint 449855920, growth limit 536870912

Erel · Jun 16, 2025

1. It is possible that there simply isn't enough memory to do what you are trying to do.
2. Nothing else can be said until you provide more information, including the full stack trace from the logs and how you convert the images. And where the images come from. And so on.

heldenssjoerd · Jun 16, 2025

Sorry, I thought you might had enough at just the first line. See below.

We are taking pictures of (damaged) goods at max resolution (customer wishes). Converting these pictures to base64 string and then adding them to the XMLBuilder.

B4X:

'code to add an photo to the xml.
x = x.element("sf")
                    x = x.element("sf1").text(tFoto.sFile).up 'base64 string of the picture, already converted.
                    x = x.element("sf2").text(fBehandel.ZendingID&"_"&(i+1)&"_"&getTimeNoLimiterUnique&".JPEG").up 'give an name to the picture

                        x = x.element("sf3").text( 0).up 'identifier

                    x = x.up

Full error. Added just 7 pictures.

B4X:

java.lang.OutOfMemoryError: Failed to allocate a 197210232 byte allocation with 25165824 free bytes and 78MB until OOM, max allowed footprint 479584288, growth limit 536870912
    at java.util.Arrays.copyOf(Arrays.java:3260)
    at java.lang.AbstractStringBuilder.ensureCapacityInternal(AbstractStringBuilder.java:125)
    at java.lang.AbstractStringBuilder.append(AbstractStringBuilder.java:660)
    at java.lang.StringBuilder.append(StringBuilder.java:203)
    at java.util.AbstractMap.toString(AbstractMap.java:561)
    at anywheresoftware.b4a.objects.collections.Map$MyMap.toString(Map.java:296)
    at java.lang.String.valueOf(String.java:2896)
    at java.lang.StringBuilder.append(StringBuilder.java:132)
    at java.util.AbstractMap.toString(AbstractMap.java:559)
    at anywheresoftware.b4a.objects.collections.Map$MyMap.toString(Map.java:296)
    at java.lang.String.valueOf(String.java:2896)
    at java.lang.StringBuilder.append(StringBuilder.java:132)
    at java.util.AbstractMap.toString(AbstractMap.java:559)
    at anywheresoftware.b4a.objects.collections.Map$MyMap.toString(Map.java:296)
    at anywheresoftware.b4a.AbsObjectWrapper.toString(AbsObjectWrapper.java:141)
    at java.lang.String.valueOf(String.java:2896)
    at anywheresoftware.b4a.BA.ObjectToString(BA.java:771)
    at lmmobile.jds.android.globaal._checkxml_valid(globaal.java:3676)
    at lmmobile.jds.android.globaal._savestatusfile(globaal.java:14612)
    at lmmobile.jds.android.starter$ResumableSub_ZendingOpslaan.resume(starter.java:26902)
    at lmmobile.jds.android.starter._zendingopslaan(starter.java:25809)
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4a.BA.raiseEvent2(BA.java:221)
    at anywheresoftware.b4a.keywords.Common.CallSub4(Common.java:1114)
    at anywheresoftware.b4a.keywords.Common.CallSubNew(Common.java:1061)
    at lmmobile.jds.android.lm_wachttijd._overzend_click(lm_wachttijd.java:887)
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4a.BA.raiseEvent2(BA.java:221)
    at anywheresoftware.b4a.BA.raiseEvent2(BA.java:205)
    at anywheresoftware.b4a.BA.raiseEvent(BA.java:201)
    at anywheresoftware.b4a.objects.ViewWrapper$1.onClick(ViewWrapper.java:80)
    at android.view.View.performClick(View.java:7339)
    at android.widget.TextView.performClick(TextView.java:14275)
    at android.view.View.performClickInternal(View.java:7305)
    at android.view.View.access$3200(View.java:846)
    at android.view.View$PerformClick.run(View.java:27787)
    at android.os.Handler.handleCallback(Handler.java:873)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:214)
    at android.app.ActivityThread.main(ActivityThread.java:7078)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:494)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:964)

Erel · Jun 17, 2025

1. The error happens in CheckXML_Valid. Please post its code.
2. Resizing the images before converting them to strings will significantly reduce the memory required.

heldenssjoerd · Jun 17, 2025

1. I've fixed an bug (didn't check if the file exists) in the CheckXML_Valid function. However an new error occurs (see below)
2. Resizing isn't an option. The customer wants most detailed pictures.

B4X:

globaal_savestatusfile (java line: 14613)
java.lang.OutOfMemoryError: Failed to allocate a 51770376 byte allocation with 25165824 free bytes and 34MB until OOM, max allowed footprint 525484520, growth limit 536870912
    at java.lang.StringFactory.newStringFromChars(StringFactory.java:267)
    at java.lang.StringBuffer.toString(StringBuffer.java:671)
    at java.io.StringWriter.toString(StringWriter.java:210)
    at com.jamesmurty.utils.XMLBuilder.asString2(XMLBuilder.java:1014)
    at com.jamesmurty.utils.XMLBuilder.asString(XMLBuilder.java:1053)
    at lmmobile.jds.android.globaal._savestatusfile(globaal.java:14613)
    at lmmobile.jds.android.starter$ResumableSub_ZendingOpslaan.resume(starter.java:26902)
    at lmmobile.jds.android.starter._zendingopslaan(starter.java:25809)
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4a.BA.raiseEvent2(BA.java:221)
    at anywheresoftware.b4a.keywords.Common.CallSub4(Common.java:1114)
    at anywheresoftware.b4a.keywords.Common.CallSubNew(Common.java:1061)
    at lmmobile.jds.android.lm_wachttijd._overzend_click(lm_wachttijd.java:887)
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4a.BA.raiseEvent2(BA.java:221)
    at anywheresoftware.b4a.BA.raiseEvent2(BA.java:205)
    at anywheresoftware.b4a.BA.raiseEvent(BA.java:201)
    at anywheresoftware.b4a.objects.ViewWrapper$1.onClick(ViewWrapper.java:80)
    at android.view.View.performClick(View.java:7339)
    at android.widget.TextView.performClick(TextView.java:14275)
    at android.view.View.performClickInternal(View.java:7305)
    at android.view.View.access$3200(View.java:846)
    at android.view.View$PerformClick.run(View.java:27787)
    at android.os.Handler.handleCallback(Handler.java:873)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:214)
    at android.app.ActivityThread.main(ActivityThread.java:7078)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:494)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:964)

heldenssjoerd · Jun 17, 2025

The error occurs on the line:

B4X:

File.WriteString(Map_Wachtrij, sFilename, x.asString)

Erel · Jun 18, 2025

It happens in the XML generation step. The image size is 50mb and it fails to allocate the required memory.

ernschd · Jul 1, 2025

Would it be an option to compress the photos? In other words, to use the highest resolution, but zipped, for example.

Erel · Jul 2, 2025

Both JPEG and PNG formats are compressed. Zipping them will not change their size much.

emexes · Jul 2, 2025

Erel said:
Both JPEG and PNG formats are compressed.

But not to the same degree. PNG is lossless and I've found usually compresses a 24-bit photo to 1/2th original size. JPEG has an adjustable quality setting, and typically compresses a 24-bit photo between from 1/10th original size at quality=90 to 1/30th original size at quality =50.

Erel said:
Zipping them will not change their size much

emexes · Jul 2, 2025

ernschd said:
but zipped

heldenssjoerd said:
Converting these pictures to base64 string

Zipping won't reduce JPEG or PNG files by very much (eg, probably less than 1%) but it should at least recover the 2 "unused" bits out of 8 for base64, eg reduce size by a tad under 25%, to a tad over 75% of original size.

emexes · Jul 2, 2025

heldenssjoerd said:
Added just 7 pictures.

B4X:

java.lang.OutOfMemoryError: Failed to allocate a 197210232 byte allocation

197 million bytes for 7 pictures = about 28 MB per picture, which suggests the pictures have not (yet) been compressed using JPEG.

Doing that should reduce the sizes by about 90% (or more, if you decrease the quality factor). Things are much more managable at those sizes. Perhaps see if you can get the images after they've been saved to storage by the camera app - however large those picture files are, they are at about the best resolution etc that you're going to get, and any image data larger than that isn't going to contain more actual non-hallucinatory detail.

TBH most consumer digital camera photos can be reduced to half their original dimensions ie reduce number of pixels (image file size) by 75%, without noticeable loss of quality or detail, because the image sensors are returning separate 8-bit red, green or blue pixels, not composite 24-bit red, green and blue pixels. Although that reasoning might be hard to sell to your customers, and it could be better (simpler) to live with needlessly-larger image files than have your customers thinking you're trying to bilk them.

MrKim · Jul 7, 2025

You might try compressing a few images, show your customer the compressed and uncompressed and ask them to tell them which is which

TILogistic · Jul 7, 2025

Better WEBP compression:

You can convert from PNG or JPG to WebP format, or from WebP to PNG or JPG.

Use the native Android method (API 18+).

Example: PNG to WebP

Ref:

[B4X] WebP images

Cross platform library that loads the new WebP format images. Android natively supports this format so the regular LoadBitmap methods will also work. B4i - If you are using a local builder then download the frameworks and add them to the builder...

www.b4x.com

Note:
This is related to this other post.

B4A - Create a input mask and write data to a xml file

Hello, is there anyone who create for me a input from, write data to a xml file and upload the file to a cloud storage. Even i need a list with all xml files created to modifiy or delete the xml. Thank you for supporting me

www.b4x.com

Android Question Write large files (multiple photos)

heldenssjoerd

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Erel

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heldenssjoerd

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Erel

B4X founder

heldenssjoerd

Member

Erel

B4X founder

heldenssjoerd

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heldenssjoerd

Member

Erel

B4X founder

ernschd

Active Member

Erel

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emexes

Expert

emexes

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emexes

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MrKim

Well-Known Member

TILogistic

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[B4X] WebP images

B4A - Create a input mask and write data to a xml file

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