Android data Storage (ii) Use of files

In Android, we can put some data directly in the form of a file to be present in the device. For example: Some text files, PDF files, audio and video files and pictures. Android provides a way to read and write files.

The standard Java file input stream (FileInputStream) is obtained through the Context.openfileinput () method, and the standard Java file output stream is obtained through the Context.openfileoutput () method ( FileOutputStream). Use

The Resources.openrawresource (R.raw.mydatafile) method returns InputStream.

For example, create a new activity, add two TextView and two buttons, click the first button, write the data on the TextView to a file, click the second button, and write the data in the file to TextView.

Mainactivity.java:

public class mainactivity extends activity {    private  string filename =  "file.txt";     private textview mytext1,mytext2 ;     @Override     protected void oncreate (Bundle  savedinstancestate)  {        super.oncreate (savedInstanceState);         setcontentview (R.layout.activity_main);         mytext1= (TextView) This.findviewbyid (R.ID.TEXT1);         mytext2= (TextView) This.findviewbyid (R.ID.TEXT2);         button button1= (Button) This.findviewbyid (r.id.btn_read);         button button2= (Button) This.findviewbyid (r.id.btn_write);         button1.setonclicklisteneR (New onclicklistener () {             @Override             public void onclick (View  ARG0)  {                 // TODO Auto-generated method stub                 mytext2.settext (Read ());             }        });         button2.setonclicklistener (New onclicklistener ()  {              @Override              public void onclick (view arg0)  {                 // todo auto-generated method stub                 write (Mytext1.getText (). toString ());            }         });     }    protected string read () {         try {             fileinputstream fis = openfileinput (filename);             try {                 byte[] buffer = new byte[fis.available ()];                 fis.read (buffer);                 return new string (buffer);             } catch  (Ioexception e)  {                //  TODO Auto-generated catch block                 e.printstacktrace ();             }        } catch  ( Filenotfoundexception e)  {            //  TODO Auto-generated catch block             e.printstacktrace ();        }         return null;&nbSp;   }    protected void write (STRING STR)  {         try {             fileoutputstream fos = openfileoutput (filename,mode_append);             try {                 fos.write (Str.getbytes ());                 fos.close ();             } catch  (ioexception e)  {                 // TODO  auto-generated catch block                 e.printstacktrace ();            }         } catch  (filenotfoundexception e)  {             // TODO Auto-generated catch block             e.printstacktrace ();         }    }}

Activity_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:id= "@+id/text1"          android:layout_width= "Match_parent"          android:layout_height= "Wrap_content"         android:text= " I am Text1 "/>    <button android:id=" @+id/btn_write "         android:layout_width= "Match_parent"         android: layout_height= "Wrap_content"         android:text= "Write"/>     <textview android:id="@+id/text2"         android:layout_width= "Match_parent"          android:layout_height= "Wrap_content"          android:text= "I am Text2"/>    <button android:id= "@+id/btn_read"         android:layout_width= "Match_parent"          android:layout_height= "Wrap_content"          android:text= "read"/>    </linearlayout>

The results of the operation are as follows: Click Write to write the first textview to the file, click Read to readout the data to the second TextView

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Android data Storage (ii) Use of files