android external storage java code example

Example of reading and writing data in the android external storage

activity_main.xml

Drag the 2 edittexts, 2 textviews and 2 buttons from the pallete, now the activity_main.xml file will like this:

File: activity_main.xml

1. <?xml version="1.0" encoding="utf-8"?>  
2. <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"  
3.     xmlns:app="http://schemas.android.com/apk/res-auto"  
4.     xmlns:tools="http://schemas.android.com/tools"  
5.     android:layout_width="match_parent"  
6.     android:layout_height="match_parent"  
7.     tools:context="example.now.com.externalstorage.MainActivity">  
8.   
9.     <EditText  
10.         android:id="@+id/editText1"  
11.         android:layout_width="wrap_content"  
12.         android:layout_height="wrap_content"  
13.         android:layout_alignParentRight="true"  
14.         android:layout_alignParentTop="true"  
15.         android:layout_marginRight="20dp"  
16.         android:layout_marginTop="24dp"  
17.         android:ems="10" >  
18.   
19.         <requestFocus />  
20.     </EditText>  
21.   
22.     <EditText  
23.         android:id="@+id/editText2"  
24.         android:layout_width="wrap_content"  
25.         android:layout_height="wrap_content"  
26.         android:layout_alignRight="@+id/editText1"  
27.         android:layout_below="@+id/editText1"  
28.         android:layout_marginTop="24dp"  
29.         android:ems="10" />  
30.   
31.     <TextView  
32.         android:id="@+id/textView1"  
33.         android:layout_width="wrap_content"  
34.         android:layout_height="wrap_content"  
35.         android:layout_alignBaseline="@+id/editText1"  
36.         android:layout_alignBottom="@+id/editText1"  
37.         android:layout_alignParentLeft="true"  
38.         android:text="File Name:" />  
39.   
40.     <TextView  
41.         android:id="@+id/textView2"  
42.         android:layout_width="wrap_content"  
43.         android:layout_height="wrap_content"  
44.         android:layout_alignBaseline="@+id/editText2"  
45.         android:layout_alignBottom="@+id/editText2"  
46.         android:layout_alignParentLeft="true"  
47.         android:text="Data:" />  
48.   
49.     <Button  
50.         android:id="@+id/button1"  
51.         android:layout_width="wrap_content"  
52.         android:layout_height="wrap_content"  
53.         android:layout_alignLeft="@+id/editText2"  
54.         android:layout_below="@+id/editText2"  
55.         android:layout_marginLeft="70dp"  
56.         android:layout_marginTop="16dp"  
57.         android:text="save" />  
58.   
59.     <Button  
60.         android:id="@+id/button2"  
61.         android:layout_width="wrap_content"  
62.         android:layout_height="wrap_content"  
63.         android:layout_alignBaseline="@+id/button1"  
64.         android:layout_alignBottom="@+id/button1"  
65.         android:layout_toRightOf="@+id/button1"  
66.         android:text="read" />  
67. </RelativeLayout>  

---

Provide permission for the external storage

You need to provide the WRITE_EXTERNAL_STORAGE permission.

1. <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>  

File: Activity_Manifest.xml

1. <?xml version="1.0" encoding="utf-8"?>  
2. <manifest xmlns:android="http://schemas.android.com/apk/res/android"  
3.     package="example.now.com.externalstorage">  
4.     <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>  
5.     <application  
6.         android:allowBackup="true"  
7.         android:icon="@mipmap/ic_launcher"  
8.         android:label="@string/app_name"  
9.         android:roundIcon="@mipmap/ic_launcher_round"  
10.         android:supportsRtl="true"  
11.         android:theme="@style/AppTheme">  
12.         <activity android:name=".MainActivity">  
13.             <intent-filter>  
14.                 <action android:name="android.intent.action.MAIN" />  
15.   
16.                 <category android:name="android.intent.category.LAUNCHER" />  
17.             </intent-filter>  
18.         </activity>  
19.     </application>  
20.   
21. </manifest>  

Activity class

Lets write the code to write and read data from the android external storage.

File: MainActivity.java

1. package example.now.com.externalstorage;  
2.   
3. import android.support.v7.app.AppCompatActivity;  
4. import android.os.Bundle;  
5. import android.view.View;  
6. import android.widget.Button;  
7. import android.widget.EditText;  
8. import android.widget.Toast;  
9.   
10. import java.io.BufferedReader;  
11. import java.io.File;  
12. import java.io.FileInputStream;  
13. import java.io.FileNotFoundException;  
14. import java.io.FileOutputStream;  
15. import java.io.IOException;  
16. import java.io.InputStreamReader;  
17. import java.io.OutputStreamWriter;  
18.   
19. public class MainActivity extends AppCompatActivity {  
20.     EditText editTextFileName,editTextData;  
21.     Button saveButton,readButton;  
22.     @Override  
23.     protected void onCreate(Bundle savedInstanceState) {  
24.         super.onCreate(savedInstanceState);  
25.         setContentView(R.layout.activity_main);  
26.   
27.         editTextFileName=findViewById(R.id.editText1);  
28.         editTextData=findViewById(R.id.editText2);  
29.         saveButton=findViewById(R.id.button1);  
30.         readButton=findViewById(R.id.button2);  
31.   
32.         //Performing action on save button  
33.         saveButton.setOnClickListener(new View.OnClickListener(){  
34.   
35.             @Override  
36.             public void onClick(View arg0) {  
37.                 String filename=editTextFileName.getText().toString();  
38.                 String data=editTextData.getText().toString();  
39.   
40.                 FileOutputStream fos;  
41.                 try {  
42.                     File myFile = new File("/sdcard/"+filename);  
43.                     myFile.createNewFile();  
44.                     FileOutputStream fOut = new FileOutputStream(myFile);  
45.                     OutputStreamWriter myOutWriter = new OutputStreamWriter(fOut);  
46.                     myOutWriter.append(data);  
47.                     myOutWriter.close();  
48.                     fOut.close();  
49.                     Toast.makeText(getApplicationContext(),filename + "saved",Toast.LENGTH_LONG).show();  
50.                 } catch (FileNotFoundException e) {e.printStackTrace();}  
51.                 catch (IOException e) {e.printStackTrace();}  
52.             }  
53.         });  
54.   
55.         //Performing action on Read Button  
56.         readButton.setOnClickListener(new View.OnClickListener(){  
57.             @Override  
58.             public void onClick(View arg0) {  
59.                 String filename=editTextFileName.getText().toString();  
60.                 StringBuffer stringBuffer = new StringBuffer();  
61.                 String aDataRow = "";  
62.                 String aBuffer = "";  
63.                 try {  
64.                     File myFile = new File("/sdcard/"+filename);  
65.                     FileInputStream fIn = new FileInputStream(myFile);  
66.                     BufferedReader myReader = new BufferedReader(  
67.                             new InputStreamReader(fIn));  
68.                     while ((aDataRow = myReader.readLine()) != null) {  
69.                         aBuffer += aDataRow + "\n";  
70.                     }  
71.                     myReader.close();  
72.                 } catch (IOException e) {  
73.                     e.printStackTrace();  
74.                 }  
75.                 Toast.makeText(getApplicationContext(),aBuffer,Toast.LENGTH_LONG).show();  
76.             }  
77.         });  
78.     }  
79. }