Will Externa Storage in Ipad Os Be Writable or Read Only

Android external storage can be used to write and save data, read configuration files etc. This article is continuation of the Android Internal Storage tutorial in the series of tutorials on structured data storage in android.

Android External Storage

External storage such as SD card can likewise shop awarding data, there's no security enforced upon files y'all relieve to the external storage.
In general in that location are two types of External Storage:

• Principal External Storage: In built shared storage which is "attainable by the user by plugging in a USB cable and mounting it as a drive on a host figurer". Example: When we say Nexus 5 32 GB.
• Secondary External Storage: Removable storage. Example: SD Card

All applications can read and write files placed on the external storage and the user tin remove them. We demand to check if the SD bill of fare is available and if we can write to it. Once we've checked that the external storage is available only then nosotros can write to it else the save button would be disabled.

Android External Storage Example Project Construction

Firstly, we need to make sure that the awarding has permission to read and write data to the users SD card, so lets open up the AndroidManifest.xml and add the following permissions:

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

Likewise, external storage may be tied up past the user having mounted it every bit a USB storage device. And so nosotros need to check if the external storage is available and is non read only.

                                  if (!isExternalStorageAvailable() || isExternalStorageReadOnly()) {      saveButton.setEnabled(imitation);   }    private static boolean isExternalStorageReadOnly() {     Cord extStorageState = Surround.getExternalStorageState();     if (Surroundings.MEDIA_MOUNTED_READ_ONLY.equals(extStorageState)) {      return true;     }     return false;    }      private static boolean isExternalStorageAvailable() {     Cord extStorageState = Environment.getExternalStorageState();     if (Environment.MEDIA_MOUNTED.equals(extStorageState)) {      render true;     }     return false;    }                              

getExternalStorageState() is a static method of Environment to make up one's mind if external storage is shortly available or not. As you can see if the condition is faux nosotros've disabled the save button.

Android External Storage Instance Code

The activity_main.xml layout is defined equally follows:

                                  <?xml version="i.0" encoding="utf-8"?> <LinearLayout xmlns:android="https://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="Reading and Writing to External Storage"         android:textSize="24sp"/>      <EditText android:id="@+id/myInputText"         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:ems="10" android:lines="v"         android:minLines="iii" android:gravity="top|left"         android:inputType="textMultiLine">          <requestFocus />     </EditText>      <LinearLayout     android:layout_width="match_parent" android:layout_height="wrap_content"     android:orientation="horizontal"         android:weightSum="1.0"         android:layout_marginTop="20dp">      <Push android:id="@+id/saveExternalStorage"         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:text="SAVE"         android:layout_weight="0.5"/>      <Button android:id="@+id/getExternalStorage"         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:layout_weight="0.5"         android:text="READ" />      </LinearLayout>      <TextView android:id="@+id/response"         android:layout_width="wrap_content"         android:layout_height="wrap_content" android:padding="5dp"         android:text=""         android:textAppearance="?android:attr/textAppearanceMedium" />  </LinearLayout>                              

Hither apart from the save and read from external storage buttons we brandish the response of saving/reading to/from an external storage in a textview unlike in the previous tutorial where android toast was displayed.

The MainActivity.coffee form is given below:

                                  package com.journaldev.externalstorage;  import java.io.BufferedReader; import java.io.DataInputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import coffee.io.IOException; import coffee.io.InputStreamReader; import android.os.Package; import android.app.Activity; import android.bone.Surroundings; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.EditText; import android.widget.TextView;   public class MainActivity extends Activity {     EditText inputText;     TextView response;     Push button saveButton,readButton;      individual Cord filename = "SampleFile.txt";     private String filepath = "MyFileStorage";     File myExternalFile;     String myData = "";      @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);          inputText = (EditText) findViewById(R.id.myInputText);         response = (TextView) findViewById(R.id.response);            saveButton =                 (Button) findViewById(R.id.saveExternalStorage);         saveButton.setOnClickListener(new OnClickListener() {             @Override             public void onClick(View five) {                 try {                     FileOutputStream fos = new FileOutputStream(myExternalFile);                     fos.write(inputText.getText().toString().getBytes());                     fos.shut();                 } take hold of (IOException eastward) {                     e.printStackTrace();                 }                 inputText.setText("");                 response.setText("SampleFile.txt saved to External Storage...");             }         });          readButton = (Button) findViewById(R.id.getExternalStorage);         readButton.setOnClickListener(new OnClickListener() {             @Override             public void onClick(View five) {                 try {                     FileInputStream fis = new FileInputStream(myExternalFile);                     DataInputStream in = new DataInputStream(fis);                     BufferedReader br =                             new BufferedReader(new InputStreamReader(in));                     String strLine;                     while ((strLine = br.readLine()) != zippo) {                         myData = myData + strLine;                     }                     in.close();                 } catch (IOException e) {                     e.printStackTrace();                 }                 inputText.setText(myData);                 response.setText("SampleFile.txt data retrieved from Internal Storage...");             }         });          if (!isExternalStorageAvailable() || isExternalStorageReadOnly()) {             saveButton.setEnabled(false);         }         else {             myExternalFile = new File(getExternalFilesDir(filepath), filename);         }       }     individual static boolean isExternalStorageReadOnly() {         String extStorageState = Environment.getExternalStorageState();         if (Surround.MEDIA_MOUNTED_READ_ONLY.equals(extStorageState)) {             return true;         }         return fake;     }      private static boolean isExternalStorageAvailable() {         String extStorageState = Environs.getExternalStorageState();         if (Environment.MEDIA_MOUNTED.equals(extStorageState)) {             return true;         }         return false;     }   }                              

1. Surround.getExternalStorageState(): returns path to internal SD mount signal similar "/mnt/sdcard"
2. getExternalFilesDir(): It returns the path to files folder within Android/information/data/application_package/ on the SD card. It is used to store any required files for your app (like images downloaded from web or cache files). In one case the app is uninstalled, whatsoever information stored in this folder is gone too.

Likewise if the external storage is not available we disable the save push button using the if status that was discussed earlier in this tutorial.

Below is our application running in android emulator, where we are writing data to file and so reading it.

Notation: Make sure your Android Emulator is configured such that it has a SD card as shown in the image dialog from AVD below. Go to Tools->Android->Android Virtual Device, edit configurations->Prove Advance Settings.

This brings an end to this tutorial. Nosotros'll hash out storage using Shared Preferences in the next tutorial. You lot tin download the final Android External Storage Projection from the beneath link.

pringleonfiess.blogspot.com

Source: https://www.journaldev.com/9400/android-external-storage-read-write-save-file

Share this post