How to read and write text in file

Hear i explain you how to read and write text in file by pragmatically and how to save them.
First we Require to create one layout for input and output means write a text and read a text and another is code file for handle file.

Demo.java  //class file

package com.dhaval.demo.activity;

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

import com.dhaval.demo.R;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;

public class demo extends Activity {

    private EditText editText;
    private TextView textView;
    private final String filename = Environment.getExternalStorageDirectory() + "/txtfile.txt";

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_demo);
        editText = (EditText) findViewById(R.id.txtedit);
        textView = (TextView) findViewById(R.id.txtview);
    }

    public void writeFile(View view) {
        FileWriter fw = null;
        BufferedWriter bw = null;
        try {
            fw = new FileWriter(filename, true);
            bw = new BufferedWriter(fw);
            bw.write(editText.getText().toString());


        } catch (IOException e) {
// TODO Auto-generated catch block            e.printStackTrace();
        } finally {
            try {
                if (bw != null)
                    bw.close();
            } catch (IOException e) {
// TODO Auto-generated catch block                e.printStackTrace();
            }
        }
    }

    public void readFile(View view) {
        FileReader fr = null;
        BufferedReader br = null;
        try {
            fr = new FileReader(filename);
            br = new BufferedReader(fr);
            String line, text = "";
            while ((line = br.readLine()) != null) {
                if (text.equals(""))
                    text = line;
                else                    text += "\r\n" + line;
            }
            textView.setText(text);

        } catch (IOException e) {
// TODO Auto-generated catch block            e.printStackTrace();
        } finally {
            try {
                if (br != null)
                    br.close();
            } catch (IOException e) {
// TODO Auto-generated catch block                e.printStackTrace();
            }
        }
    }

}

activity_demo.xml //layout file

<LinearLayout 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"
    android:orientation="vertical">
<EditText
  android:id="@+id/txtedit"
    android:layout_width="match_parent"
    android:layout_height="100dp"
    android:hint="Enter Text Hear.."
    android:singleLine="false" />
 <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">
      <Button
            android:id="@+id/btsave"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:onClick="writeFile"
            android:text="Write File" />
        <Button
            android:id="@+id/btread"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:onClick="readFile"
            android:text="Read File" />
    </LinearLayout>
    <TextView
       android:id="@+id/txtview"
       android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:singleLine="false" />
</LinearLayout>