• Android provides many kinds of storage for applications to store their data. These storage places are shared preferences, internal and external storage, SQLite storage, and storage via network connection.
• Internal storage is the storage of the private data on the device memory.
• By default these files are private and are accessed by only your application and get deleted , when user delete your application.

<LinearLayout 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:orientation="vertical" >

    <TextView
        android:id="@+id/textview"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:text="Internal storage"
        android:textSize="35dp" />

    <EditText
        android:id="@+id/editText"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="42dp"
        android:focusable="true"
        android:hint="Enter Text"
        android:textColorHighlight="#ff7eff15"
        android:textColorHint="#ffff25e6" />

    <Button
        android:id="@+id/btnSave"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Save" />

    <Button
        android:id="@+id/btnLoad"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignTop="@+id/button"
        android:text="load" />

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Read"
        android:textColor="#ff5bff1f"
        android:textSize="25dp" />

</LinearLayout>

import java.io.FileInputStream;
import java.io.FileOutputStream;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

public class InternalStorageEx extends Activity  {
   Button btnSave,btnLoad;
   TextView tv;
   EditText ed1;
   String data;
   private String file = "mydata";
   
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_internalstorage);
      
      btnSave=(Button)findViewById(R.id.btnSave);
      btnLoad=(Button)findViewById(R.id.btnLoad);
      
      ed1=(EditText)findViewById(R.id.editText);
      tv=(TextView)findViewById(R.id.textView2);
      btnSave.setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
            data=ed1.getText().toString();
            
            try {
               FileOutputStream fOut = openFileOutput(file,MODE_WORLD_READABLE);
               fOut.write(data.getBytes());
               fOut.close();
               Toast.makeText(getBaseContext(),"file saved",Toast.LENGTH_SHORT).show();
            }
            
            catch (Exception e) {
               // TODO Auto-generated catch block
               e.printStackTrace();
            }
         }
      });
      
      btnLoad.setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
            try{
               FileInputStream fin = openFileInput(file);
               int c;
               String temp="";
               
               while( (c = fin.read()) != -1){
                  temp = temp + Character.toString((char)c);
               }
               tv.setText(temp);
               Toast.makeText(getBaseContext(),"file read",Toast.LENGTH_SHORT).show();
            }
            catch(Exception e){
            }
         }
      });
   }
   
  
}