Android Read Text file in SD Card (Java Android)

package com.myapp;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;

import android.os.Bundle;
import android.os.Environment;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
             
        final File sdcard = Environment.getExternalStorageDirectory(); // /mnt/sdcard/
        
        // button1
        final Button btn1 = (Button) findViewById(R.id.button1);
        // textView1
        final TextView txtV = (TextView) findViewById(R.id.textView1);
        
        // Perform action on click 
        btn1.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
            	
            		/*** Read Text File in SD Card ***/
					try {
						
					String path = sdcard + "/mydata/thaicreate.txt";
					// or path = "/mnt/sdcard/mydata/thaicreate.txt";
					File file = new File(path);
					
					BufferedReader br = new BufferedReader(new FileReader(file));
					String line;
					line = br.readLine();
					br.close();
					file = null;
					
					txtV.setText(line);
			 		   
				} catch (Exception e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
			 		   Toast.makeText(MainActivity.this, "Failed! = " + e.getMessage() ,
					 		     Toast.LENGTH_LONG).show();   
				}
           

            }
        });
        
     
        

        
    }
    
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }
	
}

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <ListView
        android:id="@+id/listView1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_centerVertical="true" >
    </ListView>

</RelativeLayout>