Android Internal and External storage example - Store and Retrieve Data

  • Android Internal Storage 
    • Internal storage are private to your application and other applications cannot access them (nor can the user). When the user uninstalls your application, these files are removed. 
  • Android External Storage
    •  External storage such as SD card can also store application data, there's no security enforced upon files you save to the external storage. All applications can read and write files placed on the external storage and the user can remove them. 

In this example we are going to save data from an EditText to both Internal Storage and External Storage, and then try to get the data back from the respective storage places.

android internal external storage example android internal storage example android external storage example

Source for the Screen Layout - main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="fill_parent" android:layout_height="fill_parent"
 android:orientation="vertical">

 <TextView android:layout_width="fill_parent"
  android:layout_height="wrap_content" 
  android:text="@string/hello" />
 
 <EditText android:id="@+id/myInputText" 
     android:layout_width="match_parent"
  android:layout_height="wrap_content" 
  android:ems="10" android:lines="5"
  android:minLines="3" android:gravity="top|left" 
  android:inputType="textMultiLine">

  <requestFocus />
 </EditText>
 
 <Button android:id="@+id/saveInternalStorage"
  android:layout_width="match_parent" 
  android:layout_height="wrap_content"
  android:text="Save to Internal Storage" />

 <Button android:id="@+id/getInternalStorage"
  android:layout_width="match_parent" 
  android:layout_height="wrap_content"
  android:text="Display from Internal Storage" />
 
 <Button android:id="@+id/saveExternalStorage"
  android:layout_width="match_parent" 
  android:layout_height="wrap_content"
  android:text="Save to External Storage" />
 
 <Button android:id="@+id/getExternalStorage"
  android:layout_width="match_parent" 
  android:layout_height="wrap_content"
  android:text="Display from External Storage" />
 
 <TextView android:id="@+id/responseText" 
     android:layout_width="wrap_content"
  android:layout_height="wrap_content" android:padding="5dp"
  android:text="" 
  android:textAppearance="?android:attr/textAppearanceMedium" />

</LinearLayout>

Source for the Activity - AndroidStorageActivity.java

package com.as400samplecode;

import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;

import android.app.Activity;
import android.content.Context;
import android.content.ContextWrapper;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class AndroidStorageActivity extends Activity implements OnClickListener{

 private String filename = "MySampleFile.txt";
 private String filepath = "MyFileStorage";
 File myInternalFile;
 File myExternalFile;
 @Override
 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);

  ContextWrapper contextWrapper = new ContextWrapper(getApplicationContext());
  File directory = contextWrapper.getDir(filepath, Context.MODE_PRIVATE);
  myInternalFile = new File(directory , filename);

  Button saveToInternalStorage = 
   (Button) findViewById(R.id.saveInternalStorage);
  saveToInternalStorage.setOnClickListener(this);

  Button readFromInternalStorage = 
   (Button) findViewById(R.id.getInternalStorage);
  readFromInternalStorage.setOnClickListener(this);

  Button saveToExternalStorage = 
   (Button) findViewById(R.id.saveExternalStorage);
  saveToExternalStorage.setOnClickListener(this);

  Button readFromExternalStorage = 
   (Button) findViewById(R.id.getExternalStorage);
  readFromExternalStorage.setOnClickListener(this);

  //check if external storage is available and not read only  
  if (!isExternalStorageAvailable() || isExternalStorageReadOnly()) {  
   saveToExternalStorage.setEnabled(false);
  } 
  else {
   myExternalFile = new File(getExternalFilesDir(filepath), filename);
  }

 }

 public void onClick(View v) {

  EditText myInputText = (EditText) findViewById(R.id.myInputText);
  TextView responseText = (TextView) findViewById(R.id.responseText);
  String myData = "";

  switch (v.getId()) {
  case R.id.saveInternalStorage:
   try {
    FileOutputStream fos = new FileOutputStream(myInternalFile);
    fos.write(myInputText.getText().toString().getBytes());
    fos.close();
   } catch (IOException e) {
    e.printStackTrace();
   }
   myInputText.setText("");
   responseText
   .setText("MySampleFile.txt saved to Internal Storage...");
   break;

  case R.id.getInternalStorage:
   try {
    FileInputStream fis = new FileInputStream(myInternalFile);
    DataInputStream in = new DataInputStream(fis);
    BufferedReader br = 
     new BufferedReader(new InputStreamReader(in));
    String strLine;
    while ((strLine = br.readLine()) != null) {
     myData = myData + strLine;
    }
    in.close();
   } catch (IOException e) {
    e.printStackTrace();
   }
   myInputText.setText(myData);
   responseText
   .setText("MySampleFile.txt data retrieved from Internal Storage...");
   break;

  case R.id.saveExternalStorage:
   try {
    FileOutputStream fos = new FileOutputStream(myExternalFile);
    fos.write(myInputText.getText().toString().getBytes());
    fos.close();
   } catch (IOException e) {
    e.printStackTrace();
   }
   myInputText.setText("");
   responseText
   .setText("MySampleFile.txt saved to External Storage...");
   break;

  case R.id.getExternalStorage:
   try {
    FileInputStream fis = new FileInputStream(myExternalFile);
    DataInputStream in = new DataInputStream(fis);
    BufferedReader br = 
     new BufferedReader(new InputStreamReader(in));
    String strLine;
    while ((strLine = br.readLine()) != null) {
     myData = myData + strLine;
    }
    in.close();
   } catch (IOException e) {
    e.printStackTrace();
   }
   myInputText.setText(myData);
   responseText
   .setText("MySampleFile.txt data retrieved from Internal Storage...");
   break;


  }
 }

 private static boolean isExternalStorageReadOnly() {  
  String extStorageState = Environment.getExternalStorageState();  
  if (Environment.MEDIA_MOUNTED_READ_ONLY.equals(extStorageState)) {  
   return true;  
  }  
  return false;  
 }  

 private static boolean isExternalStorageAvailable() {  
  String extStorageState = Environment.getExternalStorageState();  
  if (Environment.MEDIA_MOUNTED.equals(extStorageState)) {  
   return true;  
  }  
  return false;  
 }  

}

References

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