android从文本文件读取

Question

I have a java class where it reads some data from a text file using a buffered reader and returns that data as a hash map:

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.HashMap;

public class FrequencyLoader {

     public FrequencyLoader() throws FileNotFoundException {
        }

        public HashMap<String, Double> loadUnigramFrequencies() throws FileNotFoundException, IOException {
            HashMap<String, Double> unigramFrequencies = new HashMap<String, Double>();
            String line;
            String[] splittedLine;

            BufferedReader bf = new BufferedReader(new FileReader("unigramFrequencies.txt"));

            while ((line = bf.readLine()) != null) {
                splittedLine = line.split("\\s");


                unigramFrequencies.put(splittedLine[0].trim(), Double.parseDouble(splittedLine[1].trim()));
            }

            return unigramFrequencies;
        }
}

I want to use that in my android application but when I create an instance of this class and try to execute the loadUnigramFrequencies() function in the android Activity class I am getting an error that the application has stopped unexpectedly. I am trying to run it on Samsung Galaxy S2. Should the file be placed somewhere in the android project rather than on the disk? if yes then where?

Answer 1

without a bit of logcat it is a bit trivial.

 unigramFrequencies.put(splittedLine[0].trim(), Double.parseDouble(splittedLine[1].trim()))

here for instance could be raised a null pointer execption if splittedLine[0] or splittedLine[1] is null, or parseDouble could arise a number format execption

Answer 2

I think the error might well be there :

BufferedReader bf = new BufferedReader(new FileReader("unigramFrequencies.txt"));

You should provide an absolute path here and first make sure that the file exists before accessing it or handle the exception.

If this file is some final asset, you should place it in your project assets folder and get a filereader from there.

Example (from here ):

AssetFileDescriptor descriptor = getAssets().openFd("unigramFrequencies.txt");
FileReader reader = new FileReader(descriptor.getFileDescriptor());

Note that your unigramFrequencies.txt file should be present in your <project>/assets/ directory

Answer 3

This is searching for a needle in the hay stack.

I recommend you to first learn how to use debugging in Android:
http://www.droidnova.com/debugging-in-android-using-eclipse,541.html

Also some exception handling wouldn't hurt:
http://en.wikibooks.org/wiki/Java_Programming/Throwing_and_Catching_Exceptions

The following line of code is very wrong, and it seems you don't understand file storage in android:

new FileReader("unigramFrequencies.txt")

Here it is explained:
http://developer.android.com/guide/topics/data/data-storage.html