Android Read Write File Operations

Android Read Write File Operations

Oct 31, 2015 By: Dr. Droid Android File, Android UI Design Comments: 6

Reading and Writing files in Android will be helpful if you want to read data from SD Card, store your application data as a text file. In this tutorial we are going to learn same. Below are some points that we are going to learn in today’s tutorial:

1. Write File – Write user input data into TextFile.

2. Read File – Read data from saved user data file.

3. Delete File – Delete saved file from SD Card.

4. TimeStamp – Fetching current time stamp and saved in shared preferences when file is saved.

5. File Path – Display file path to locate where the Text File is saved.

Prerequisites required for this tutorial –

SD Card Mount – Check if SD Card is mounted or not.
Create Directory – How to create directory in SD Card.
SharedPreferences – To store timestamp of saved file.

We are going to use two classes for writing and reading file to SD Card –

1. FileWriter – A specialised Writer that writes to a file in the file system. All write requests made by calling methods in this class are directly forwarded to the equivalent function of the underlying operating system. Since this may induce some performance penalty, in particular if many small write requests are made, a FileWriter is often wrapped by a BufferedWriter.

2. FileReader – A specialised Reader that reads from a file in the file system. All read requests made by calling methods in this class are directly forwarded to the equivalent function of the underlying operating system. Since this may induce some performance penalty, in particular if many small read requests are made, a FileReader is often wrapped by a BufferedReader.

Example

In this tutorial, we are going to learn how to write, read and delete File operations in Android.

VIDEO DEMO

1. Create a new project in Android Studio by navigating to File ⇒ New Android ⇒ Application Project and fill required details. By default my activity is MainActivity.java.

2. Open res=>values=strings.xml and add the following strings to it.

<resources>
    <string name="app_name">Read &amp; Write TextFile Demo</string>

    <string name="mainTitle">Read &amp; Write Text File</string>
    <string name="enterMessage">Enter your message below</string>
    <string name="saveMessage">Save Message to SD Card</string>
    <string name="readMessage">Read Message From SD Card</string>
    <string name="deleteMessage">Delete Message From SD Card</string>

</resources>

<string name="app_name">Read & Write TextFile Demo</string>

<string name="mainTitle">Read & Write Text File</string>

<string name="enterMessage">Enter your message below</string>

<string name="saveMessage">Save Message to SD Card</string>

<string name="readMessage">Read Message From SD Card</string>

<string name="deleteMessage">Delete Message From SD Card</string>

</resources>

3. Create a xml layout naming activity_main.xml and add the following code. In this layout there is one EditText to take user input and some buttons for writing, reading and delete text file and a hidden layout for showing saved text file data.

<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#eeeeee">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        android:padding="10dp">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center_horizontal"
            android:gravity="center"
            android:padding="10dp"
            android:text="@string/mainTitle"
            android:textAllCaps="true"
            android:textColor="#3F51B5"
            android:textSize="19sp" />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="10dp"
            android:padding="3dp"
            android:text="@string/enterMessage"
            android:textColor="#939393"
            android:textSize="15sp" />

        <!-- Input your Message to be save in file  -->
        <EditText
            android:id="@+id/enterMessage"
            android:layout_width="fill_parent"
            android:layout_height="180dp"
            android:background="@drawable/editttext_border"
            android:gravity="top|left"
            android:inputType="textCapSentences|textMultiLine"
            android:padding="5dp"
            android:scrollbars="vertical"
            android:textColor="#9e9e9e"
            android:textSize="16sp" />

        <!-- Save Message Button  -->
        <Button
            android:id="@+id/saveMessage"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="8dp"
            android:background="#ffffff"
            android:elevation="5dp"
            android:text="@string/saveMessage"
            android:textColor="#2196F3"
            android:textSize="15sp" />

        <!-- Read Message Button  -->
        <Button
            android:id="@+id/readMessage"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="8dp"
            android:background="#ffffff"
            android:elevation="5dp"
            android:text="@string/readMessage"
            android:textColor="#2196F3"
            android:textSize="15sp" />


        <!-- Show Message Layout  -->
        <RelativeLayout
            android:id="@+id/readMessageLayout"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="7dp"
            android:visibility="gone">

            <!-- TextView For displaying saved file path  -->
            <TextView
                android:id="@+id/savedTextFileNameandPath"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_toLeftOf="@+id/savedTextFileTime"
                android:gravity="left|center_vertical"
                android:padding="5dp"
                android:textColor="#009688"
                android:textSize="13sp" />

            <!-- TextView For displaying saved file time  -->
            <TextView
                android:id="@+id/savedTextFileTime"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_alignParentRight="true"
                android:gravity="right|center_vertical"
                android:padding="5dp"
                android:textColor="#9e9e9e"
                android:textSize="12sp" />

            <!-- TextView For displaying saved file data  -->
            <TextView
                android:id="@+id/savedFileMessageBody"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_below="@+id/savedTextFileNameandPath"
                android:gravity="center_vertical|left"
                android:padding="5dp"
                android:textColor="#616161"
                android:textSize="14sp" />

        </RelativeLayout>

        <!-- Delete Message Button  -->
        <Button
            android:id="@+id/deleteMessage"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="8dp"
            android:background="#ffffff"
            android:elevation="5dp"
            android:text="@string/deleteMessage"
            android:textColor="#2196F3"
            android:textSize="15sp" />

    </LinearLayout>
</ScrollView>

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:background="#eeeeee">

<LinearLayout

android:layout_width="match_parent"

android:layout_height="match_parent"

android:orientation="vertical"

android:padding="10dp">

<TextView

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_gravity="center_horizontal"

android:gravity="center"

android:padding="10dp"

android:text="@string/mainTitle"

android:textAllCaps="true"

android:textColor="#3F51B5"

android:textSize="19sp" />

<TextView

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_marginTop="10dp"

android:padding="3dp"

android:text="@string/enterMessage"

android:textColor="#939393"

android:textSize="15sp" />

<EditText

android:id="@+id/enterMessage"

android:layout_width="fill_parent"

android:layout_height="180dp"

android:background="@drawable/editttext_border"

android:gravity="top|left"

android:inputType="textCapSentences|textMultiLine"

android:padding="5dp"

android:scrollbars="vertical"

android:textColor="#9e9e9e"

android:textSize="16sp" />

<Button

android:id="@+id/saveMessage"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:layout_marginTop="8dp"

android:background="#ffffff"

android:elevation="5dp"

android:text="@string/saveMessage"

android:textColor="#2196F3"

android:textSize="15sp" />

<Button

android:id="@+id/readMessage"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:layout_marginTop="8dp"

android:background="#ffffff"

android:elevation="5dp"

android:text="@string/readMessage"

android:textColor="#2196F3"

android:textSize="15sp" />

<RelativeLayout

android:id="@+id/readMessageLayout"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:layout_marginTop="7dp"

android:visibility="gone">

<TextView

android:id="@+id/savedTextFileNameandPath"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_toLeftOf="@+id/savedTextFileTime"

android:gravity="left|center_vertical"

android:padding="5dp"

android:textColor="#009688"

android:textSize="13sp" />

<TextView

android:id="@+id/savedTextFileTime"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_alignParentRight="true"

android:gravity="right|center_vertical"

android:padding="5dp"

android:textColor="#9e9e9e"

android:textSize="12sp" />

<TextView

android:id="@+id/savedFileMessageBody"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:layout_below="@+id/savedTextFileNameandPath"

android:gravity="center_vertical|left"

android:padding="5dp"

android:textColor="#616161"

android:textSize="14sp" />

</RelativeLayout>

<Button

android:id="@+id/deleteMessage"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:layout_marginTop="8dp"

android:background="#ffffff"

android:elevation="5dp"

android:text="@string/deleteMessage"

android:textColor="#2196F3"

android:textSize="15sp" />

</LinearLayout>

</ScrollView>

4. Create a drawable under drawable directory naming edittext_border.xml for giving border to EditText.

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <solid android:color="#ffffff" />
    <stroke
        android:width="1px"
        android:color="#9e9e9e" />

</shape>

<?xml version="1.0" encoding="utf-8"?>

<shape xmlns:android="http://schemas.android.com/apk/res/android"

android:shape="rectangle">

<stroke

android:width="1px"

android:color="#9e9e9e" />

</shape>

5. Create a CheckForSDCard.java class for checking if SDCard is mounted or not.

com.read_write_textfile_demo;

import android.os.Environment;
 
public class CheckForSDCard {
    //Check If SD Card is present or not method
    public boolean isSDCardPresent() {
        if (Environment.getExternalStorageState().equals(
 
                Environment.MEDIA_MOUNTED)) {
            return true;
        }
        return false;
    }
}

com.read_write_textfile_demo;

import android.os.Environment;

public class CheckForSDCard {

//Check If SD Card is present or not method

public boolean isSDCardPresent() {

if (Environment.getExternalStorageState().equals(

Environment.MEDIA_MOUNTED)) {

return true;

}

return false;

}

6. Now below are methods that i am using for writing , reading and deleting text files.

Write File Method

  //Method for writing data to text file
    private void saveMessageIntoSDCard(File savedFile, String messageBody) {
        try {

            //File writer is used for writing data
            FileWriter fWriter = new FileWriter(savedFile);
            fWriter.write(messageBody);//write data
            fWriter.flush();//flush writer
            fWriter.close();//close writer

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

//Method for writing data to text file

private void saveMessageIntoSDCard(File savedFile, String messageBody) {

try {

//File writer is used for writing data

FileWriter fWriter = new FileWriter(savedFile);

fWriter.write(messageBody);//write data

fWriter.flush();//flush writer

fWriter.close();//close writer

} catch (Exception e) {

e.printStackTrace();

}

Read File Method – Here ‘fileDirectory’ is main directory and ‘savedFile’ is our TextFile. This method will return us string data after reading text file.

 //Method that will return saved text file data after reading
    private String readMessageFromSDCard() {

        //First check if main directory is present or not
        if (!fileDirectory.exists())
            Toast.makeText(getBaseContext(), "There is no main directory present. ",
                    Toast.LENGTH_SHORT).show();
        else {

            //Then check if text file is present or not
            File savedFile = new File(fileDirectory.getAbsolutePath() + "/" + FileName);
            if (!savedFile.exists())
                Toast.makeText(getBaseContext(), "There is no such file to read data. ",
                        Toast.LENGTH_SHORT).show();
            else {
                //Finally read data using FileReader
                try {
                    FileReader rdr = new FileReader(fileDirectory.getAbsolutePath() + "/" + FileName);

                    char[] inputBuffer = new char[READ_BLOCK_SIZE];//get Block size as buffer
                    String savedData = "";
                    int charRead = rdr.read(inputBuffer);
                    //Read all data one by one by using loop and add it to string created above
                    for (int k = 0; k < charRead; k++) {
                        savedData += inputBuffer[k];
                    }
                    return savedData;//return saved data

                } catch (Exception e) {
                    e.printStackTrace();
                    Log.e("Message", e.getLocalizedMessage());
                    return null;
                }
            }
        }
        return null;
    }

//Method that will return saved text file data after reading

private String readMessageFromSDCard() {

//First check if main directory is present or not

if (!fileDirectory.exists())

Toast.makeText(getBaseContext(), "There is no main directory present. ",

Toast.LENGTH_SHORT).show();

else {

//Then check if text file is present or not

File savedFile = new File(fileDirectory.getAbsolutePath() + "/" + FileName);

if (!savedFile.exists())

Toast.makeText(getBaseContext(), "There is no such file to read data. ",

Toast.LENGTH_SHORT).show();

else {

//Finally read data using FileReader

try {

FileReader rdr = new FileReader(fileDirectory.getAbsolutePath() + "/" + FileName);

char[] inputBuffer = new char[READ_BLOCK_SIZE];//get Block size as buffer

String savedData = "";

int charRead = rdr.read(inputBuffer);

//Read all data one by one by using loop and add it to string created above

for (int k = 0; k < charRead; k++) {

savedData += inputBuffer[k];

}

return savedData;//return saved data

} catch (Exception e) {

e.printStackTrace();

Log.e("Message", e.getLocalizedMessage());

return null;

}

return null;

}

Delete File Method –

   //Delete text file method
    private void deleteMessageFromSDCard() {

        //Check if main directory is present or not
        if (!fileDirectory.exists())
            Toast.makeText(getBaseContext(), "There is no main directory present.",
                    Toast.LENGTH_SHORT).show();
        else {

            //Now Check if text file is present or not
            File savedFile = new File(fileDirectory.getAbsolutePath() + "/" + FileName);
            if (!savedFile.exists())
                Toast.makeText(getBaseContext(), "There is no saved file present.",
                        Toast.LENGTH_SHORT).show();
            else {
                savedFile.delete();//If text file is present then delete file
                Toast.makeText(getBaseContext(), "File deleted Successfully.",
                        Toast.LENGTH_SHORT).show();
            }

        }
    }

//Delete text file method

private void deleteMessageFromSDCard() {

//Check if main directory is present or not

if (!fileDirectory.exists())

Toast.makeText(getBaseContext(), "There is no main directory present.",

Toast.LENGTH_SHORT).show();

else {

//Now Check if text file is present or not

File savedFile = new File(fileDirectory.getAbsolutePath() + "/" + FileName);

if (!savedFile.exists())

Toast.makeText(getBaseContext(), "There is no saved file present.",

Toast.LENGTH_SHORT).show();

else {

savedFile.delete();//If text file is present then delete file

Toast.makeText(getBaseContext(), "File deleted Successfully.",

Toast.LENGTH_SHORT).show();

}

TimeStamp Code –

  //Get Current Date and put it in Shared Preferences
  SimpleDateFormat sdf = new SimpleDateFormat("dd-MMM-yyyy HH:mm:ss");
  String currentDateandTime = sdf.format(new Date());

//Get Current Date and put it in Shared Preferences

SimpleDateFormat sdf = new SimpleDateFormat("dd-MMM-yyyy HH:mm:ss");

String currentDateandTime = sdf.format(new Date());

7. Finally come to your MainActivity.java and add the following code.

package com.read_write_textfile_demo;

import android.content.Context;
import android.content.DialogInterface;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.os.Environment;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.RelativeLayout;
import android.widget.TextView;
import android.widget.Toast;

import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.text.SimpleDateFormat;
import java.util.Date;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private static EditText enterMessage;
    private static Button saveMessage, readMessage, deleteMessage;
    private static TextView savedMessageFileNameandPath, savedMessageTime, saveMessageData;
    private static RelativeLayout readMessageLayout;

    private static File fileDirectory = null;//Main Directory File

    private static final String DirectoryName = "Androhub Saved Files";//Main Directory Name
    private static final String FileName = "androhub.txt";//Text File Name
    private static final int READ_BLOCK_SIZE = 512;//Block Size for text File

    //Preferences to Store TimStamp when data is Saved
    private static SharedPreferences timeSharedPreferences;
    private static SharedPreferences.Editor editor;

    //Preferences Name and KeyValue for TimeStamp
    private static final String SharedPreferencesName = "TimePreferences";
    private static final String TimeKeyValue = "TimeKeyValue";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initViews();
        setListeners();
    }


    //Init All views
    private void initViews() {

        //Init shared preferences
        timeSharedPreferences = getSharedPreferences(SharedPreferencesName, Context.MODE_PRIVATE);
        editor = timeSharedPreferences.edit();

        enterMessage = (EditText) findViewById(R.id.enterMessage);

        saveMessage = (Button) findViewById(R.id.saveMessage);
        readMessage = (Button) findViewById(R.id.readMessage);
        deleteMessage = (Button) findViewById(R.id.deleteMessage);

        savedMessageFileNameandPath = (TextView) findViewById(R.id.savedTextFileNameandPath);
        savedMessageTime = (TextView) findViewById(R.id.savedTextFileTime);
        saveMessageData = (TextView) findViewById(R.id.savedFileMessageBody);

        readMessageLayout = (RelativeLayout) findViewById(R.id.readMessageLayout);


        //Check if sd card is present or not
        if (new CheckForSDCard().isSDCardPresent()) {
            fileDirectory = new File(
                    Environment.getExternalStorageDirectory() + "/"
                            + DirectoryName);
        } else
            Toast.makeText(MainActivity.this, "SD Card is not present.", Toast.LENGTH_SHORT).show();//Show toast if SD Card is not mounted
    }


    //set listeners to buttons
    private void setListeners() {
        saveMessage.setOnClickListener(this);
        readMessage.setOnClickListener(this);
        deleteMessage.setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.saveMessage:
                saveMessage();
                break;
            case R.id.readMessage:
                showSavedFileData(readMessageFromSDCard());
                break;
            case R.id.deleteMessage:
                deleteMessageFromSDCard();
                break;
        }
    }


    //Call Save Message Method
    private void saveMessage() {
        String messageBody = enterMessage.getText().toString().trim();//get Input message

        //Check if it is null or not
        if (messageBody.length() == 0 && messageBody.equals(""))
            Toast.makeText(MainActivity.this, "Please Enter some message.", Toast.LENGTH_SHORT).show();
        else {

            try {
                //Create Main Directory if not present
                if (!fileDirectory.exists())
                    fileDirectory.mkdir();

                //Make File Name under main Directory
                File savedFile = new File(fileDirectory.getAbsolutePath() + "/" + FileName);

                //If Saved File exists then check if it's size is greater than 0
                if (savedFile.exists()) {
                    if (savedFile.length() > 0)
                        appendOrOverrideSavedFile(savedFile, messageBody);//if file present then show alert for appending and overriding
                    else {
                        //else save data into file
                        saveMessageIntoSDCard(savedFile, messageBody);
                        Toast.makeText(getBaseContext(), "File saved successfully!",
                                Toast.LENGTH_SHORT).show();
                    }
                } else {
                    //If Saved file doesn't exists then create new file and save file
                    saveMessageIntoSDCard(savedFile, messageBody);
                    Toast.makeText(getBaseContext(), "File saved successfully!",
                            Toast.LENGTH_SHORT).show();
                }

            } catch (Exception e) {
                e.printStackTrace();
                Log.e("Message", e.getLocalizedMessage());

            }
        }
    }


    //Method to show alert if file already present
    private void appendOrOverrideSavedFile(final File savedFile, final String message) {
        final String savedMessage = readMessageFromSDCard();//Read saved message

        //Check if saved message not null
        if (savedMessage != null && savedMessage.length() > 0 && !savedMessage.equals("")) {

            //If not null then show alert
            AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
            builder.setTitle("Choose..");
            builder.setMessage("What do you want to do with message?nnAppend data to current saved file or override saved data.");
            builder.setPositiveButton("OVERRIDE", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialogInterface, int i) {
                    //If Override is selected then textfile data is overrided
                    saveMessageIntoSDCard(savedFile, message);
                    Toast.makeText(getBaseContext(), "File Overrided Successfully!",
                            Toast.LENGTH_SHORT).show();
                }
            });
            builder.setNegativeButton("APPEND", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialogInterface, int i) {
                    //If Append is selected then textfile data is appended with new data
                    saveMessageIntoSDCard(savedFile, savedMessage + "nn" + message);
                    Toast.makeText(getBaseContext(), "File Appended Successfully!",
                            Toast.LENGTH_SHORT).show();
                }
            });
            builder.setNeutralButton("CANCEL", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialogInterface, int i) {

                }
            });
            AlertDialog ad = builder.create();
            ad.setCancelable(true);
            ad.setCanceledOnTouchOutside(true);
            ad.show();
        } else
            //If there is nothing to read from saved fie then simply add data to file
            saveMessageIntoSDCard(savedFile, message);

    }


    //Method for writing data to text file
    private void saveMessageIntoSDCard(File savedFile, String messageBody) {
        try {

            //File writer is used for writing data
            FileWriter fWriter = new FileWriter(savedFile);
            fWriter.write(messageBody);//write data
            fWriter.flush();//flush writer
            fWriter.close();//close writer


            //Get Current Date and put it in Shared Preferences
            SimpleDateFormat sdf = new SimpleDateFormat("dd-MMM-yyyy HH:mm:ss");
            String currentDateandTime = sdf.format(new Date());

            editor.putString(TimeKeyValue, currentDateandTime);
            editor.commit();

        } catch (Exception e) {
            e.printStackTrace();
        }
    }


    //Method that will return saved text file data after reading
    private String readMessageFromSDCard() {

        //First check if main directory is present or not
        if (!fileDirectory.exists())
            Toast.makeText(getBaseContext(), "There is no main directory present. ",
                    Toast.LENGTH_SHORT).show();
        else {

            //Then check if text file is present or not
            File savedFile = new File(fileDirectory.getAbsolutePath() + "/" + FileName);
            if (!savedFile.exists())
                Toast.makeText(getBaseContext(), "There is no such file to read data. ",
                        Toast.LENGTH_SHORT).show();
            else {
                //Finally read data using FileReader
                try {
                    FileReader rdr = new FileReader(fileDirectory.getAbsolutePath() + "/" + FileName);

                    char[] inputBuffer = new char[READ_BLOCK_SIZE];//get Block size as buffer
                    String savedData = "";
                    int charRead = rdr.read(inputBuffer);
                    //Read all data one by one by using loop and add it to string created above
                    for (int k = 0; k < charRead; k++) {
                        savedData += inputBuffer[k];
                    }
                    return savedData;//return saved data

                } catch (Exception e) {
                    e.printStackTrace();
                    Log.e("Message", e.getLocalizedMessage());
                    return null;
                }
            }
        }
        return null;
    }

    //Show Saved data
    private void showSavedFileData(String savedMessage) {

        //Check if saved data is not null
        if (savedMessage != null && savedMessage.length() > 0 && !savedMessage.equals("")) {

            //Check if TimeStamp is present or not
            if (timeSharedPreferences.contains(TimeKeyValue))
                savedMessageTime.setText(timeSharedPreferences.getString(TimeKeyValue, ""));//Dispaly saved timestamp

            savedMessageFileNameandPath.setText(FileName + " - inside '" + fileDirectory.getAbsolutePath() + "'");//Display file path
            saveMessageData.setText(savedMessage);//display saved data
            readMessageLayout.setVisibility(View.VISIBLE);//Make visible the read message layout
        }
    }

    //Delete text file method
    private void deleteMessageFromSDCard() {

        //Check if main directory is present or not
        if (!fileDirectory.exists())
            Toast.makeText(getBaseContext(), "There is no main directory present.",
                    Toast.LENGTH_SHORT).show();
        else {

            //Now Check if text file is present or not
            File savedFile = new File(fileDirectory.getAbsolutePath() + "/" + FileName);
            if (!savedFile.exists())
                Toast.makeText(getBaseContext(), "There is no saved file present.",
                        Toast.LENGTH_SHORT).show();
            else {
                savedFile.delete();//If text file is present then delete file
                readMessageLayout.setVisibility(View.GONE);//hide read file layout

                //Remove Saved TimeStamp
                editor.remove(TimeKeyValue);
                editor.commit();

                Toast.makeText(getBaseContext(), "File deleted Successfully.",
                        Toast.LENGTH_SHORT).show();
            }

        }
    }
}

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

152

153

154

155

156

157

158

159

160

161

162

163

164

165

166

167

168

169

170

171

172

173

174

175

176

177

178

179

180

181

182

183

184

185

186

187

188

189

190

191

192

193

194

195

196

197

198

199

200

201

202

203

204

205

206

207

208

209

210

211

212

213

214

215

216

217

218

219

220

221

222

223

224

225

226

227

228

229

230

231

232

233

234

235

236

237

238

239

240

241

242

243

244

245

246

247

248

249

250

251

252

253

254

255

256

257

258

259

260

261

262

263

264

265

266

267

268

269

270

271

272

273

274

275

276

277

278

279

280

281

282

283

284

285

286

287

288

289

290

291

292

293

294

295

296

297

298

299

300

301

302

package com.read_write_textfile_demo;

import android.content.Context;

import android.content.DialogInterface;

import android.content.SharedPreferences;

import android.os.Bundle;

import android.os.Environment;

import android.support.v7.app.AlertDialog;

import android.support.v7.app.AppCompatActivity;

import android.util.Log;

import android.view.View;

import android.widget.Button;

import android.widget.EditText;

import android.widget.RelativeLayout;

import android.widget.TextView;

import android.widget.Toast;

import java.io.File;

import java.io.FileReader;

import java.io.FileWriter;

import java.text.SimpleDateFormat;

import java.util.Date;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

private static EditText enterMessage;

private static Button saveMessage, readMessage, deleteMessage;

private static TextView savedMessageFileNameandPath, savedMessageTime, saveMessageData;

private static RelativeLayout readMessageLayout;

private static File fileDirectory = null;//Main Directory File

private static final String DirectoryName = "Androhub Saved Files";//Main Directory Name

private static final String FileName = "androhub.txt";//Text File Name

private static final int READ_BLOCK_SIZE = 512;//Block Size for text File

//Preferences to Store TimStamp when data is Saved

private static SharedPreferences timeSharedPreferences;

private static SharedPreferences.Editor editor;

//Preferences Name and KeyValue for TimeStamp

private static final String SharedPreferencesName = "TimePreferences";

private static final String TimeKeyValue = "TimeKeyValue";

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

initViews();

setListeners();

}

//Init All views

private void initViews() {

//Init shared preferences

timeSharedPreferences = getSharedPreferences(SharedPreferencesName, Context.MODE_PRIVATE);

editor = timeSharedPreferences.edit();

enterMessage = (EditText) findViewById(R.id.enterMessage);

saveMessage = (Button) findViewById(R.id.saveMessage);

readMessage = (Button) findViewById(R.id.readMessage);

deleteMessage = (Button) findViewById(R.id.deleteMessage);

savedMessageFileNameandPath = (TextView) findViewById(R.id.savedTextFileNameandPath);

savedMessageTime = (TextView) findViewById(R.id.savedTextFileTime);

saveMessageData = (TextView) findViewById(R.id.savedFileMessageBody);

readMessageLayout = (RelativeLayout) findViewById(R.id.readMessageLayout);

//Check if sd card is present or not

if (new CheckForSDCard().isSDCardPresent()) {

fileDirectory = new File(

Environment.getExternalStorageDirectory() + "/"

+ DirectoryName);

} else

Toast.makeText(MainActivity.this, "SD Card is not present.", Toast.LENGTH_SHORT).show();//Show toast if SD Card is not mounted

}

//set listeners to buttons

private void setListeners() {

saveMessage.setOnClickListener(this);

readMessage.setOnClickListener(this);

deleteMessage.setOnClickListener(this);

}

@Override

public void onClick(View view) {

switch (view.getId()) {

case R.id.saveMessage:

saveMessage();

break;

case R.id.readMessage:

showSavedFileData(readMessageFromSDCard());

break;

case R.id.deleteMessage:

deleteMessageFromSDCard();

break;

}

//Call Save Message Method

private void saveMessage() {

String messageBody = enterMessage.getText().toString().trim();//get Input message

//Check if it is null or not

if (messageBody.length() == 0 && messageBody.equals(""))

Toast.makeText(MainActivity.this, "Please Enter some message.", Toast.LENGTH_SHORT).show();

else {

try {

//Create Main Directory if not present

if (!fileDirectory.exists())

fileDirectory.mkdir();

//Make File Name under main Directory

File savedFile = new File(fileDirectory.getAbsolutePath() + "/" + FileName);

//If Saved File exists then check if it's size is greater than 0

if (savedFile.exists()) {

if (savedFile.length() > 0)

appendOrOverrideSavedFile(savedFile, messageBody);//if file present then show alert for appending and overriding

else {

//else save data into file

saveMessageIntoSDCard(savedFile, messageBody);

Toast.makeText(getBaseContext(), "File saved successfully!",

Toast.LENGTH_SHORT).show();

}

} else {

//If Saved file doesn't exists then create new file and save file

saveMessageIntoSDCard(savedFile, messageBody);

Toast.makeText(getBaseContext(), "File saved successfully!",

Toast.LENGTH_SHORT).show();

}

} catch (Exception e) {

e.printStackTrace();

Log.e("Message", e.getLocalizedMessage());

}

//Method to show alert if file already present

private void appendOrOverrideSavedFile(final File savedFile, final String message) {

final String savedMessage = readMessageFromSDCard();//Read saved message

//Check if saved message not null

if (savedMessage != null && savedMessage.length() > 0 && !savedMessage.equals("")) {

//If not null then show alert

AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);

builder.setTitle("Choose..");

builder.setMessage("What do you want to do with message?nnAppend data to current saved file or override saved data.");

builder.setPositiveButton("OVERRIDE", new DialogInterface.OnClickListener() {

@Override

public void onClick(DialogInterface dialogInterface, int i) {

//If Override is selected then textfile data is overrided

saveMessageIntoSDCard(savedFile, message);

Toast.makeText(getBaseContext(), "File Overrided Successfully!",

Toast.LENGTH_SHORT).show();

}

});

builder.setNegativeButton("APPEND", new DialogInterface.OnClickListener() {

@Override

public void onClick(DialogInterface dialogInterface, int i) {

//If Append is selected then textfile data is appended with new data

saveMessageIntoSDCard(savedFile, savedMessage + "nn" + message);

Toast.makeText(getBaseContext(), "File Appended Successfully!",

Toast.LENGTH_SHORT).show();

}

});

builder.setNeutralButton("CANCEL", new DialogInterface.OnClickListener() {

@Override

public void onClick(DialogInterface dialogInterface, int i) {

}

});

AlertDialog ad = builder.create();

ad.setCancelable(true);

ad.setCanceledOnTouchOutside(true);

ad.show();

} else

//If there is nothing to read from saved fie then simply add data to file

saveMessageIntoSDCard(savedFile, message);

}

//Method for writing data to text file

private void saveMessageIntoSDCard(File savedFile, String messageBody) {

try {

//File writer is used for writing data

FileWriter fWriter = new FileWriter(savedFile);

fWriter.write(messageBody);//write data

fWriter.flush();//flush writer

fWriter.close();//close writer

//Get Current Date and put it in Shared Preferences

SimpleDateFormat sdf = new SimpleDateFormat("dd-MMM-yyyy HH:mm:ss");

String currentDateandTime = sdf.format(new Date());

editor.putString(TimeKeyValue, currentDateandTime);

editor.commit();

} catch (Exception e) {

e.printStackTrace();

}

//Method that will return saved text file data after reading

private String readMessageFromSDCard() {

//First check if main directory is present or not

if (!fileDirectory.exists())

Toast.makeText(getBaseContext(), "There is no main directory present. ",

Toast.LENGTH_SHORT).show();

else {

//Then check if text file is present or not

File savedFile = new File(fileDirectory.getAbsolutePath() + "/" + FileName);

if (!savedFile.exists())

Toast.makeText(getBaseContext(), "There is no such file to read data. ",

Toast.LENGTH_SHORT).show();

else {

//Finally read data using FileReader

try {

FileReader rdr = new FileReader(fileDirectory.getAbsolutePath() + "/" + FileName);

char[] inputBuffer = new char[READ_BLOCK_SIZE];//get Block size as buffer

String savedData = "";

int charRead = rdr.read(inputBuffer);

//Read all data one by one by using loop and add it to string created above

for (int k = 0; k < charRead; k++) {

savedData += inputBuffer[k];

}

return savedData;//return saved data

} catch (Exception e) {

e.printStackTrace();

Log.e("Message", e.getLocalizedMessage());

return null;

}

return null;

}

//Show Saved data

private void showSavedFileData(String savedMessage) {

//Check if saved data is not null

if (savedMessage != null && savedMessage.length() > 0 && !savedMessage.equals("")) {

//Check if TimeStamp is present or not

if (timeSharedPreferences.contains(TimeKeyValue))

savedMessageTime.setText(timeSharedPreferences.getString(TimeKeyValue, ""));//Dispaly saved timestamp

savedMessageFileNameandPath.setText(FileName + " - inside '" + fileDirectory.getAbsolutePath() + "'");//Display file path

saveMessageData.setText(savedMessage);//display saved data

readMessageLayout.setVisibility(View.VISIBLE);//Make visible the read message layout

}

//Delete text file method

private void deleteMessageFromSDCard() {

//Check if main directory is present or not

if (!fileDirectory.exists())

Toast.makeText(getBaseContext(), "There is no main directory present.",

Toast.LENGTH_SHORT).show();

else {

//Now Check if text file is present or not

File savedFile = new File(fileDirectory.getAbsolutePath() + "/" + FileName);

if (!savedFile.exists())

Toast.makeText(getBaseContext(), "There is no saved file present.",

Toast.LENGTH_SHORT).show();

else {

savedFile.delete();//If text file is present then delete file

readMessageLayout.setVisibility(View.GONE);//hide read file layout

//Remove Saved TimeStamp

editor.remove(TimeKeyValue);

editor.commit();

Toast.makeText(getBaseContext(), "File deleted Successfully.",

Toast.LENGTH_SHORT).show();

}

8. Finally, all done you can use above code to save your data in File.

Thanks.

Download Source Code – >

6 Comments

Bhushan

Tuesday, February 23rd, 2016

Hi. Great tutorial. However, it does’t work on Android 6.0 due to changed in write permissions. Here’s a link to get an idea of how to implement write permissions:

http://stackoverflow.com/questions/33139754/android-6-0-marshmallow-cannot-write-to-sd-card

Can u please rewrite the code by using this? or at least guild me how to do it to make this app run on MM. Thanks.

Droid

Tuesday, February 23rd, 2016

Hi Bhushan,

Do the below following steps for MarshMallow Device :

1. private static final int REQUEST_WRITE_STORAGE = 112;
declare this as global variable for Request Id.

2. While reading and writing on SD Card use this code before doing that task

boolean hasPermission = (ContextCompat.checkSelfPermission(activity,
Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED);
if (!hasPermission) {
ActivityCompat.requestPermissions(parentActivity,
new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
REQUEST_WRITE_STORAGE);
}
else{
//Call read or write method}

3. Now to access request permission that user is accepted to grant permission then use this method for acceptance and denial

@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
switch (requestCode)
{
case REQUEST_WRITE_STORAGE: {
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED)
{
//Call read or write method
} else
{
Toast.makeText(parentActivity, “The app was not allowed to write to your storage. Hence, it cannot function properly. Please consider granting it this permission”, Toast.LENGTH_LONG).show();
}
}
}

}

Hope it helps.

Thanks

hassan

Friday, April 7th, 2017

can you sent the coding for this tutorial.. i’m using android 6.0.. realy appreciate that.. tq

Dr. Droid

Saturday, April 8th, 2017

Hi Hassan,

Please click on Download Source Code again. I replaced new code having Marshmallow permission. Hope it will help you.

Thanks

hashir

Wednesday, April 22nd, 2020

Having issues in downloading the code. Its a 404

Dr. Droid

Thursday, May 7th, 2020

Hi Hashir,

You can download the code from here: https://github.com/sonusurender/Read_Write_File_Operations_Demo

Thanks