Why return null length in Android mode?

erkosone

This function in java mode works well.. but in android mode returns null length of folder.. any solution??

PImage[] loadImages(String nameFolder) {
  java.io.File folder = new java.io.File(dataPath("")+"/"+nameFolder);
  String[] filenames = folder.list();
  //println(filenames.length);
  //println(dataPath("")+"/"+nameFolder);
  PImage[] img = new PImage[filenames.length];
  for (int i = 0; i < filenames.length; i++) {
    //println("Loading: "+filenames[i]);
    img[i] = loadImage(dataPath("") + "/" + nameFolder + "/" + filenames[i]);
  }
  return img;
}

kfrajer

First question: did you enable read permissions?

Then, consider checking this post:

https://forum.processing.org/two/discussion/21424/using-android-studio-how-to-i-load-media-files#latest

For instance: https://forum.processing.org/two/discussion/comment/61200/#Comment_61200
https://forum.processing.org/two/discussion/21167/accessing-sd-cards-for-storage#latest

That last one might not help but it is for reference.

I have to say this was tested with Android Mode 3.0.2ish or earlier. Not sure if it works with AM 4.0 beta 9 (latest version I think).

Kf

akenaton

@erkosone===

your code is ok in java mode but it cannot work in android mode because when compiling P5 creates a folder for "assets" replacing the data folder and its contents (in your case some subfolder with images).That's why it returns null: data folder does not exist anymore... So you have to use AssetManager from android for retrieving all your images, putting them in a PImage[] and loading them.

erkosone

Any example of this AssetManager for load a folter with images?

akenaton

@erkosone===

code snippet below; the subfolder "dossier" is in the data folder (at the begining!) - In my case i have put only 1 image inside it; but of course you can change that && get all images with a for loop.

    import android.content.Context;// useless here but...
    import android.app.Activity;
    import android.os.Environment; // useless here but...
    import android.content.res.AssetManager;
    import android.graphics.Bitmap;//useless here but if you want to use android for //transforming the image when decoding from file inputstream....

    PImage imga;
    Activity act;



    void setup(){

      size(600,400);
      background(255);
      act= this.getActivity();//for fragments
      AssetManager assetManager = act.getAssets();
      try{
      String[] imgPath = assetManager.list("dossier");
      println (imgPath);
      imga = loadImage(imgPath[0]);//only 1 in the subfolder....

      }catch(IOException ex){
           System.out.println (ex.toString());   
       }
    image(imga, 0,0);
    };

erkosone

Hi, y try to work with this example but not works.. the same error apears. Null pointer access.

Can you check it? https://www.dropbox.com/s/sltcqu65grhzz9q/testAssetManager.rar?dl=0

erkosone

DOWNLOAD EXAMPLE: https://www.dropbox.com/s/sltcqu65grhzz9q/testAssetManager.rar?dl=0

import android.content.Context;// useless here but...
import android.app.Activity;
import android.os.Environment; // useless here but...
import android.content.res.AssetManager;
import android.graphics.Bitmap;//useless here but if you want to use android for //transforming the image when decoding from file inputstream....
//........................................................
PImage[] img;
//........................................................
void setup(){
  size(displayWidth, displayHeight);
  orientation(PORTRAIT);
  img = loadImages("cat/");
  image(img[0], 0, 0);
}
//........................................................
PImage[] loadImages(String folderName_){
  Activity act;
  PImage[] img_ = null;
  act = this.getActivity();
  AssetManager assetManager = act.getAssets();
  try{
    String[] imgPath = assetManager.list(folderName_);
    println(imgPath.length);
    for(int i=0; i>imgPath.length; i++){
      img_[i] = loadImage(imgPath[i]);
    }
  }
  catch(IOException ex){
       System.out.println (ex.toString());   
  }
  return img_;
}
//........................................................

akenaton

@erkosone=== of course your code cannot run because you transformed mine in a weird way:

• first error is line 24 : i > must be i<....

• second error with your PImage[]: you have to initialize it with some length (imagPath) but you initialize it only to "null"...that 's why in my code i used an arrayList().

• third error is with your slash: you have only to give the subfolder name; doing with a slash is useless and can fire an illegal argument exception

• below my code rewritten to integrate your method ... try it!

  import android.content.Context;
  import android.app.Activity;
  import android.content.res.AssetManager;
  
  
  PImage imga;
  Activity act;
  String finalPath;
  ArrayList<PImage> images= new ArrayList<PImage>();
  PImage[] img;
  
  void setup(){
    size(600,400);
    background(255);
    act= this.getActivity();
    img = loadImages("dossier");
    imga = img[0];
    image(imga, 0, 0);
  
  }
  
  void draw(){
  
  }
  
  
  PImage[] loadImages(String folderName_){
  
  
    AssetManager assetManager = act.getAssets();
    try{
      String[] imgPath = assetManager.list(folderName_);
      println(imgPath.length);
      img = new PImage[imgPath.length];
       for(int i=0; i<imgPath.length; i++){
       img[i] = loadImage(imgPath[i]);
      }
  
  
    }
    catch(IOException ex){
         System.out.println (ex.toString());   
    }
    println(img.length);
    return img;
  }
  

akenaton

so???

erkosone

Sorry, i try it today and reply to you. ;)

erkosone

YOU ARE THE BOSS!!!!

Works perfectly!!!!!!!

This is the final code:

import android.content.Context;
import android.app.Activity;
import android.content.res.AssetManager;


Activity act;
String finalPath;
ArrayList<PImage> images= new ArrayList<PImage>();
PImage[] img;

void setup(){
  size(displayWidth, displayHeight);
  //background(255);
  img = loadImages("cat");
  image(img[0], 0, 0);

}

void draw(){

}


PImage[] loadImages(String folderName_){
  act= this.getActivity();
  AssetManager assetManager = act.getAssets();
  try{
    String[] imgPath = assetManager.list(folderName_);
    img = new PImage[imgPath.length];
     for(int i=0; i<imgPath.length; i++){
     img[i] = loadImage(folderName_ + "/" + imgPath[i]);
    }
  }
  catch(IOException ex){
       System.out.println (ex.toString());   
  }
  return img;
}

Thank you very much, this is an excellent resource loader function, it saves me a lot of workavoiding reading files one by one.

This function should be in the language directly available, it is very good.