Question

I have one class called “Global” and two other activities. In each activity I want to create an instance of class Global for reading the first line of a text file called “textfile”. For some reason, it does not work

Here is the code of Global class (in file Global.java):

import android.app.Activity;
public class Global extends Activity {
    public String line;
    public Global() {
        InputStream file = getResources().openRawResource(R.raw.textfile);
        BufferedReader input = new BufferedReader(new InputStreamReader(file));
        try {
            line = input.readLine();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
} 

Here are codes for a antivity called “HelloWorld” (in file HelloWorld.java) which has an instance of class Global and is to display of first line of “textfile”

public class HelloWorld extends Activity{   
    Global gb;
    TextView myTV;
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.helloworld);
            gb=new Global();
        myTV = (TextView) findViewById(R.id.textView1);
        myTV.setText("First line is: "+gb.line);
    }

}

Answer 1

There is not need to unnecessarily have Global extending Activity
Class.

What you can do is you pass context in global constructor.

The correct way would be

HelloWorld.java

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;

    public class HelloWorld extends Activity{   
        Global gb;
        TextView myTV;
        protected void onCreate(Bundle savedInstanceState) {
            // TODO Auto-generated method stub
            super.onCreate(savedInstanceState);
            setContentView(R.layout.helloworld);

            gb=new Global(this);

            myTV = (TextView) findViewById(R.id.textView1);
            myTV.setText("First line is: "+gb.getLine());
        }
    }

Global.java

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;


public class Global {
    private AbcActivity abcActivity;
    public String line;

    public Global(AbcActivity abcActivity) {
        this.abcActivity = abcActivity;
    }

    public String getLine() {
        InputStream file = abcActivity.getResources().openRawResource(
                R.raw.textfile);
        BufferedReader input = new BufferedReader(new InputStreamReader(file));
        try {
            line = input.readLine();
            return line;
        } catch (IOException e) {
            e.printStackTrace();
            return "Error reading File!";
        }
    }

}