ViewInformationActivity.java

package com.hgo.externalstorage;
import android.content.Intent;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

public class ViewInformationActivity extends AppCompatActivity {

    TextView textView;

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

        // findViewById returns a view, we need to cast it into TextView
        textView = (TextView) findViewById(R.id.textView_get_saved_data);
    }

    public void showPublicData(View view) {
        // Accessing the saved data from the downloads folder
        File folder = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);

        // geeksData represent the file data that is saved publicly
        File file = new File(folder, "myfiledata.txt");
        String data = getdata(file);
        if (data != null) {
            textView.setText(data);
        } else {
            textView.setText("No Data Found");
        }
    }

    public void showPrivateData(View view) {

        // GeeksForGeeks represent the folder name to access privately saved data
        File folder = getExternalFilesDir("mydir");

        // gft.txt is the file that is saved privately
        File file = new File(folder, "myfile.txt");
        String data = getdata(file);
        if (data != null) {
            textView.setText(data);
        } else {
            textView.setText("No Data Found");
        }
    }

    public void back(View view) {
        Intent intent = new Intent(ViewInformationActivity.this, MainActivity.class);
        startActivity(intent);
    }

    // getdata() is the method which reads the data
    // the data that is saved in byte format in the file
    private String getdata(File myfile) {
        FileInputStream fileInputStream = null;
        try {
            fileInputStream = new FileInputStream(myfile);
            int i = -1;
            StringBuffer buffer = new StringBuffer();
            while ((i = fileInputStream.read()) != -1) {
                buffer.append((char) i);
            }
            return buffer.toString();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (fileInputStream != null) {
                try {
                    fileInputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return null;
    }
}