File handling

Learn file handling in android apps.

MainActivity.java

 package com.example.ashish.filehandleing;  
 import android.app.AlertDialog;  
 import android.app.Dialog;  
 import android.content.Context;  
 import android.content.DialogInterface;  
 import android.support.v7.app.AppCompatActivity;  
 import android.os.Bundle;  
 import android.view.Menu;  
 import android.view.MenuItem;  
 import android.view.View;  
 import android.widget.EditText;  
 import android.widget.TextView;  
 import android.widget.Toast;  
 import java.io.File;  
 import java.io.FileInputStream;  
 import java.io.FileOutputStream;  
 import java.io.OutputStreamWriter;  
 public class MainActivity extends AppCompatActivity {  
   @Override  
   protected void onCreate(Bundle savedInstanceState) {  
     super.onCreate(savedInstanceState);  
     setContentView(R.layout.activity_main);  
   }  
   @Override  
   public boolean onCreateOptionsMenu(Menu menu) {  
     getMenuInflater().inflate(R.menu.menu_main, menu);  
     return true;  
   }  
   public void open(View v )  
   {  
     AlertDialog.Builder alertdialogbuilder=new AlertDialog.Builder(this);  
     alertdialogbuilder.setMessage("Are you sure to save the file");  
     alertdialogbuilder.setPositiveButton("yes",new DialogInterface.OnClickListener(){  
       @Override  
     public void onClick(DialogInterface arg ,int gk)  
       {  
         EditText ed = (EditText) findViewById(R.id.editText);  
         String tv = ed.getText().toString();  
         try {  
           FileOutputStream fileos = openFileOutput("short.txt", MODE_PRIVATE);  
           OutputStreamWriter outputwriter = new OutputStreamWriter(fileos);  
           outputwriter.write(ed.getText().toString());  
           outputwriter.close();  
           Toast.makeText(MainActivity.this,"Your file is saved",Toast.LENGTH_LONG).show();  
         } catch (Exception e) {  
           e.printStackTrace();  
         }  
       }  
     });  
     alertdialogbuilder.setNegativeButton("No", new DialogInterface.OnClickListener() {  
       @Override  
       public void onClick(DialogInterface dilog, int which) {  
         finish();  
       }  
     });  
     AlertDialog alertdialog=alertdialogbuilder.create();  
     alertdialog.show();  
   }  
 public void readfile(View v)  
 {  
   try  
   {  
     TextView text=(TextView)findViewById(R.id.textView2);  
     int c;  
     String str="";  
     FileInputStream FI=openFileInput("short.txt");  
     while((c=FI.read())!=-1)  
     {  
       str=str+(char)c;  
     }  
     text.setText(str);  
     FI.close();  
   }  
   catch (Exception e) {  
     e.printStackTrace();  
   }  
 }  
   @Override  
   public boolean onOptionsItemSelected(MenuItem item) {  
     int id = item.getItemId();  
     if (id == R.id.action_settings) {  
       return true;  
     }  
     return super.onOptionsItemSelected(item);  
   }  
 }  

activity_main.xml

 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"  
   xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"  
   android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"  
   android:paddingRight="@dimen/activity_horizontal_margin"  
   android:paddingTop="@dimen/activity_vertical_margin"  
   android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">  
   <TextView android:text="@string/abc" android:layout_width="match_parent"  
     android:layout_height="wrap_content"  
     android:id="@+id/textView"  
     android:layout_gravity="center"  
     android:layout_alignParentTop="true"  
     android:layout_alignParentRight="true"  
     android:layout_alignParentEnd="true" />  
   <EditText  
     android:layout_width="match_parent"  
     android:layout_height="wrap_content"  
     android:id="@+id/editText"  
     android:layout_below="@+id/textView"  
     android:layout_alignParentLeft="true"  
     android:layout_alignParentStart="true"  
     android:layout_marginTop="38dp" />  
   <Button  
     android:layout_width="match_parent"  
     android:layout_height="wrap_content"  
     android:text="Submit"  
     android:id="@+id/button"  
     android:layout_marginTop="54dp"  
     android:onClick="open"  
     android:layout_below="@+id/editText"  
     android:layout_alignParentLeft="true"  
     android:layout_alignParentStart="true" />  
   <Button  
     android:layout_width="match_parent"  
     android:layout_height="wrap_content"  
     android:text="Read"  
     android:id="@+id/button2"  
     android:onClick="readfile"  
     android:layout_above="@+id/textView2"  
     android:layout_alignParentLeft="true"  
     android:layout_alignParentStart="true"  
     android:layout_marginBottom="56dp" />  
   <TextView  
     android:layout_width="wrap_content"  
     android:layout_height="wrap_content"  
     android:text="New Text"  
     android:id="@+id/textView2"  
     android:layout_alignParentBottom="true"  
     android:layout_centerHorizontal="true"  
     android:layout_marginBottom="85dp" />  
 </RelativeLayout>