getResourceAsStream() returning null

Question

I have a java .jar library, and from there i'm trying to access a file of my Android project with:

InputStream inputStream = getClass().getResourceAsStream("/folder/data.txt");
someMethod(inputStream); // inputStream is null

But the inputStream is always null. I'm confused about where should i put my /folder/data.txt in order to be able to find it from the .jar.

From within the .jar project i can find the data.txt, doing the following in eclipse:

MyProject > properties > java build path > libraries > Add class folder

and this code:

InputStream inputStream = getClass().getResourceAsStream("/data.txt"); // without the folder

This is the structure of the Java Project:

MyJavaProject

  - src
    - com.example
      - something.java
      - folder
           - data.txt

Now, inside the Android Project i try to do the same but i keep getting null (inputStream):

MyAndroidProject

  - src
    - several packages
    - folder
       - data.txt
  - libs
     - my jar

Where should i put my data.txt? or should i change something in my .jar

I've read a lot of similar questions but i haven't found a solution. I've also read about getResourceAsStream() but i'm obviously not getting it.

Answer 1

getResourceAsStream() isn't terribly useful in android. It refers to files embedded in a JAR or classpath container, not android Resources. You probably want to use the android assets feature instead. You can simply place the asset file ("data.txt") under your project's assets/ directory.

To get an InputStream for the asset, you can use the AssetsManager, like this (error handling is omitted for clarity:

// get the assets manager from your activity or `Context`
final AssetsManager am = getAssets();
final InputStream   in = am.open("data.txt");
// do stuff with the input stream

Another approach is to use Resources instead, but this depends on the contents of data.txt Resources are intended for data types that android knows how to load and parse, such as drawables, strings, and various xml files. Assets are for raw data that you are going to read and parse yourself.