Create an application to read file from the sdcard and display that file content to the screen.


MainActivity.java

package com.example.assignment19;

import androidx.annotation.NonNull;

import androidx.annotation.Nullable;

import androidx.appcompat.app.AppCompatActivity;

import android.Manifest;

import android.app.Activity;

import android.content.Intent;

import android.content.pm.PackageManager;

import android.net.Uri;

import android.os.Build;

import android.os.Bundle;

import android.os.Environment;

import android.view.View;

import android.webkit.PermissionRequest;

import android.widget.Button;

import android.widget.TextView;

import android.widget.Toast;

import java.io.BufferedReader;

import java.io.File;

import java.io.FileReader;

import java.io.IOException;

import java.security.Permission;

public class MainActivity extends AppCompatActivity {

    private  static  final int READ_REQUEST_CODE = 42;

    private  static  final  int PERMISSION_REQUEST_STORAGE = 1000;

    Button b_load;

    TextView tv_output;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        if (Build.VERSION.SDK_INT>=Build.VERSION_CODES.M && checkCallingOrSelfPermission(Manifest.permission.READ_EXTERNAL_STORAGE)

        != PackageManager.PERMISSION_GRANTED){

            requestPermissions(new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, PERMISSION_REQUEST_STORAGE);

        }

        b_load=(Button) findViewById(R.id.b_load);

        tv_output=(TextView)findViewById(R.id.tv_output);

        b_load.setOnClickListener(new View.OnClickListener() {

            @Override

            public void onClick(View v) {

                performFileSearch();

            }

        });

    }

    private String readText (String input){

        File file = new  File(Environment.getExternalStorageDirectory(),input);

        StringBuilder text = new StringBuilder();

        try {

            BufferedReader br = new BufferedReader(new FileReader(file));

            String line;

            while  ((line= br.readLine()) != null) {

                text.append(line);

                text.append("\n");

            }

            br.close();

        }catch (IOException e){

            e.printStackTrace();

        }

        return text.toString();

}

private  void performFileSearch(){

        Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);

        intent.addCategory(Intent.CATEGORY_OPENABLE);

        intent.setType("text/*");

        startActivityForResult(intent, READ_REQUEST_CODE);

}

    @Override

    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {

        super.onActivityResult(requestCode, resultCode, data);

        if (requestCode == READ_REQUEST_CODE && resultCode == Activity.RESULT_OK) {

            if (data != null) {

                Uri uri = data.getData();

                String path = uri.getPath();

                path = path.substring(path.indexOf(":") + 1);

                if (path.contains("emulated")){

                    path = path.substring(path.indexOf("0") + 1);

                }

                Toast.makeText(this, ""+ path, Toast.LENGTH_SHORT).show();

                tv_output.setText(readText(path));

            }

        }

    }

    @Override

    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {

        if (requestCode == PERMISSION_REQUEST_STORAGE){

            if (grantResults[0] == PackageManager.PERMISSION_GRANTED){

                Toast.makeText(this, "Permission Granted!!", Toast.LENGTH_SHORT).show();

                finish();

            }

        }

    }

}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>

<AbsoluteLayout 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=".MainActivity">

    <Button

        android:id="@+id/b_load"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:text="Load" />

    <TextView

        android:id="@+id/tv_output"

        android:layout_width="158dp"

        android:layout_height="wrap_content"

        android:layout_x="127dp"

        android:layout_y="181dp"

        android:padding="10dp"

        android:text=""

        android:textColor="#0E0E0E"

        android:textSize="24sp" />

</AbsoluteLayout>

AndroidMainfest.xml

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.example.assignment19">

    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE">

    </uses-permission>

    <application

        android:allowBackup="true"

        android:icon="@mipmap/ic_launcher"

        android:label="@string/app_name"

        android:roundIcon="@mipmap/ic_launcher_round"

        android:supportsRtl="true"

        android:theme="@style/AppTheme">

        <activity android:name=".MainActivity">

            <intent-filter>

                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />

            </intent-filter>

        </activity>

    </application>

</manifest>




Output

After reading the file,it will display on the screen

To download follow this link : Program 19