Android Internal Storage Example

There are several ways(Shared preferences, Internal storage, External storage, SQLite) to save data in android. Here we will discuss about Internal Storage.

Note: Saving files to the internal storage are private to the application, and other applications will not have access to these files.

Output will look like below:

Download code from here: internal storage

1. Create a project and name it as Internal Storage

2. Open activity_main.xml and paste below code

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.internalstorage.MainActivity">

    <EditText
        android:id="@+id/editText"
        android:layout_width="match_parent"
        android:layout_height="200dp"
        android:fontFamily="monospace"
        android:hint="Enter some data here"
        android:paddingLeft="10dp"
        android:textStyle="bold" />

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/editText"
        android:layout_marginTop="20dp"
        android:gravity="center">

        <Button
            android:id="@+id/write"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:text="write" />

        <Button
            android:id="@+id/read"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_toRightOf="@id/write"
            android:gravity="center"
            android:text="read" />
    </RelativeLayout>

</RelativeLayout>

3. Open MainActivity.java and paste below code

package com.internalstorage;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

public class MainActivity extends AppCompatActivity {

    private EditText enteredData;
    private Button write, read;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        enteredData = (EditText) findViewById(R.id.editText);

        write = (Button) findViewById(R.id.write);
        read = (Button) findViewById(R.id.read);

        write.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (enteredData.getText().toString().length() > 0) {
                    writeData(enteredData.getText().toString());
                } else {
                    showMessage();
                }

            }
        });


        read.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                enteredData.setText(readData());
            }
        });
    }

    private void showMessage() {
        Toast.makeText(MainActivity.this, "Please enter some data", Toast.LENGTH_SHORT).show();
    }

    private void writeData(String data) {

        try {
            //Using FileOutputStream we can write data to the specified file
            //openFileOutput method will take file name and mode as parameters, and return instance of fileOutputStream

            //openFileOutput method is used to create and save a file
            FileOutputStream fileOutputStream = openFileOutput("notes", MODE_PRIVATE);
            fileOutputStream.write(data.getBytes());
            fileOutputStream.close();

            Toast.makeText(MainActivity.this,"Data saved successfully",Toast.LENGTH_SHORT).show();

        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    private String readData() {

        int c;
        StringBuilder data = new StringBuilder();
        try {
            //openFileInput method is used to open and read a file
            FileInputStream fileInputStream = openFileInput("notes");
            //checking for end of file
            while ((c = fileInputStream.read()) != -1) {
                data.append(Character.toString((char) c));
            }
            fileInputStream.close();

        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        return data.toString();
    }
}