CODEWITHSUNDEEP
javaandroid
JUAN
JUAN

Reputation: 523

File, FileReader, BufferedReader return null on Android

I'm using Java to program in Android where I have two clases: first is MainActivity.java and the second is Tokenizer.java. In Tokenizer I use File, FileReader and BufferedReader to read a txt file. In this class I use the next code:

package net.try.........;
import java.io.File;
import java.io.FileReader;
import java.io.BufferedReader;
import android.content.Context;

public class Tokenizer {
    BufferedReader br;
    FileReader fr;
    File f;

    public void leerPath ( ) {      

    try {
        f = new File("F:path...../file.txt");
        fr = new FileReader(f);
        br = new BufferedReader(fr);
    } 

    catch (FileNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();                
    }
}

When debugging the MainActivity "f" those have the path where the file is FileReader then dysplay that f is null, and so br is also null. Why is the reason that, when using in Java the code works but Java/Android is there something misisng?

this is the code in main activiti

public class MainActivity extends MapActivity {

public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Tokenizer ob1=new Tokenizer();
ob1.leerPath();
}
}

Upvotes: 0

Views: 1715

Answers (1)

Jon Skeet
Jon Skeet

Reputation: 1500785

The problem is that you've declared a load of instance variables, but then you've also declared a load of local variables which "hide" the instance variables. You're assigning values to the local variables, but that doesn't affect the instance variables at all.

This:

File f = new File("F:path...../file.txt");
FileReader fr = new FileReader(f);
BufferedReader br = new BufferedReader(fr);

should just be:

f = new File("F:path...../file.txt");
fr = new FileReader(f);
br = new BufferedReader(fr);

That's assuming you really want them to be instance variables. Why do you need all three anyway? Don't you just need the reader you're reading from?

Upvotes: 2

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