Tag: APK

i’ve just written an android app using android studio. The app compiles with no errors and i have also generated the signed apk, but if i try to install it on my smartphone (samsung galaxy S8), it says “app not installed”. What can be the matter?
Here there are my java codes, my gradle, my manifest.

package com.unicampania.btapp;

import android.bluetooth.BluetoothSocket;
import android.os.Handler;
import android.os.Message;
import android.util.Log;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;

public class ConnectedThread extends Thread{
    private final BluetoothSocket mmSocket;
    private final InputStream mmInStream;
    private final OutputStream mmOutStream;
    public static final int RESPONSE_MESSAGE = 10;
    Handler uih;

    public ConnectedThread(BluetoothSocket socket, Handler uih){
        mmSocket = socket;
        InputStream tmpIn = null;
        OutputStream tmpOut = null;
        this.uih = uih;
        Log.i("(THREAD-CT)","Creating thread");
        try{
            tmpIn = socket.getInputStream();
            tmpOut = socket.getOutputStream();

        } catch(IOException e) {
            Log.e("(THREAD-CT)","Error:"+ e.getMessage());
        }

        mmInStream = tmpIn;
        mmOutStream = tmpOut;

        try {
            mmOutStream.flush();
        } catch (IOException e) {
            return;
        }
        Log.i("(THREAD-CT)","IO's obtained");

    }
    public void run(){
        //byte() buffer = new byte(1024);
        //int bytes;
        BufferedReader br = new BufferedReader(new InputStreamReader(mmInStream));
        Log.i("(THREAD-CT)","Starting thread");
        while(true){
            try{
                // bytes = mmInStream.read(buffer);
                String resp = br.readLine();
                //Transfer these data to the UI thread
                Message msg = new Message();
                msg.what = RESPONSE_MESSAGE;
                msg.obj = resp;
                uih.sendMessage(msg);
            }catch(IOException e){
                break;
            }
        }
        Log.i("(THREAD-CT)","While loop ended");
    }

    public void write(byte() bytes){
        try{
            Log.i("(THREAD-CT)", "Writting bytes");
            mmOutStream.write(bytes);

        }catch(IOException e){}
    }

    public void cancel(){
        try{
            mmSocket.close();
        }catch(IOException e){}
    }
}

package com.unicampania.btapp;

import android.annotation.SuppressLint;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import androidx.appcompat.widget.Toolbar;
import java.io.IOException;
import java.util.UUID;
import androidx.appcompat.app.AppCompatActivity;

public class Main extends AppCompatActivity {

    public final static String MODULE_MAC = "98:D3:34:90:6F:A1";
    public final static int REQUEST_ENABLE_BT = 1;
    private static final UUID MY_UUID = UUID.fromString("00001101-0000-1000-8000-00805f9b34fb");

    BluetoothAdapter bta;
    BluetoothSocket mmSocket;
    BluetoothDevice mmDevice;
    ConnectedThread btt = null;
    Button switchLight, switchRelay;
    TextView response;
    boolean lightflag = false;
    boolean relayFlag = true;
    public Handler mHandler;

    @SuppressLint("NewApi")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_ardcon);
        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        Log.i("(BLUETOOTH)", "Creating listeners");
        response = (TextView) findViewById(R.id.response);
        switchRelay = (Button) findViewById(R.id.relay);
        switchLight = (Button) findViewById(R.id.switchlight);
        switchLight.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Log.i("(BLUETOOTH)", "Attempting to send data");
                if (mmSocket.isConnected() && btt != null) { //if we have connection to the bluetoothmodule
                    if (!lightflag) {
                        String sendtxt = "LY";
                        btt.write(sendtxt.getBytes());
                        lightflag = true;
                    } else {
                        String sendtxt = "LN";
                        btt.write(sendtxt.getBytes());
                        lightflag = false;
                    }
                } else {
                    Toast.makeText(Main.this, "Something went wrong", Toast.LENGTH_LONG).show();
                }
            }
        });
        switchRelay.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Log.i("(BLUETOOTH)", "Attempting to send data");
                if (mmSocket.isConnected() && btt != null) { //if we have connection to the bluetoothmodule
                    if(relayFlag){
                        String sendtxt = "RY";
                        btt.write(sendtxt.getBytes());
                        relayFlag = false;
                    }else{
                        String sendtxt = "RN";
                        btt.write(sendtxt.getBytes());
                        relayFlag = true;
                    }

                    //disable the button and wait for 4 seconds to enable it again
                    switchRelay.setEnabled(false);
                    new Thread(new Runnable() {
                        @Override
                        public void run() {
                            try{
                                Thread.sleep(4000);
                            }catch(InterruptedException e){
                                return;
                            }

                            runOnUiThread(new Runnable() {
                                @Override
                                public void run() {
                                    switchRelay.setEnabled(true);
                                }
                            });

                        }
                    }).start();
                } else {
                    Toast.makeText(Main.this, "Something went wrong", Toast.LENGTH_LONG).show();
                }
            }
        });

        bta = BluetoothAdapter.getDefaultAdapter();

        //if bluetooth is not enabled then create Intent for user to turn it on
        if(!bta.isEnabled()){
            Intent enableBTIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
            startActivityForResult(enableBTIntent, REQUEST_ENABLE_BT);
        }else{
            initiateBluetoothProcess();
        }
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if(resultCode == RESULT_OK && requestCode == REQUEST_ENABLE_BT){
            initiateBluetoothProcess();
        }
    }

    public void initiateBluetoothProcess(){

        if(bta.isEnabled()){

            //attempt to connect to bluetooth module
            BluetoothSocket tmp = null;
            mmDevice = bta.getRemoteDevice(MODULE_MAC);

            //create socket
            try {
                tmp = mmDevice.createRfcommSocketToServiceRecord(MY_UUID);
                mmSocket = tmp;
                mmSocket.connect();
                Log.i("(BLUETOOTH)","Connected to: "+mmDevice.getName());
            }catch(IOException e){
                try{mmSocket.close();}catch(IOException c){return;}
            }

            Log.i("(BLUETOOTH)", "Creating handler");
            mHandler = new Handler(Looper.getMainLooper()){
                @Override
                public void handleMessage(Message msg) {
                    //super.handleMessage(msg);
                    if(msg.what == ConnectedThread.RESPONSE_MESSAGE){
                        String txt = (String)msg.obj;
                        if(response.getText().toString().length() >= 30){
                            response.setText("");
                            response.append(txt);
                        }else{
                            response.append("n" + txt);
                        }
                    }
                }
            };

            Log.i("(BLUETOOTH)", "Creating and running Thread");
            btt = new ConnectedThread(mmSocket,mHandler);
            btt.start();


        }
    }

}

GRADLE
plugins {
    id 'com.android.application'
}

android {
    compileSdkVersion 30
    buildToolsVersion "30.0.3"

    defaultConfig {
        applicationId "com.unicampania.btapp"
        minSdkVersion 21
        targetSdkVersion 30
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
    lintOptions {

        checkReleaseBuilds false

    }
}

dependencies {

    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support:design:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    implementation 'android.arch.navigation:navigation-fragment:1.0.0'
    implementation 'android.arch.navigation:navigation-ui:1.0.0'
    implementation 'androidx.appcompat:appcompat:1.2.0'
    testImplementation 'junit:junit:4.+'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
}

MANIFEST
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    package="com.unicampania.btapp"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="16"
        android:targetSdkVersion="30" />

    <uses-permission android:name="android.permission.BLUETOOTH" />
    <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />

    <!-- Include required permissions for Google Maps API to run. -->
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.INTERNET" />

    <uses-feature
        android:glEsVersion="0x00020000"
        android:required="true" />

    <application
        android:allowBackup="true"
        android:appComponentFactory="androidx.core.app.CoreComponentFactory"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:testOnly="true"
        android:theme="@style/AppTheme"
        tools:replace="android:appComponentFactory"
        >
        <activity
            android:name=".Main"
            android:label="@string/title_activity_btapp"
            android:theme="@style/AppTheme.NoActionBar"
            tools:ignore="Instantiatable">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <!-- Needs to be explicitly declared on P+ -->
        <uses-library
            android:name="org.apache.http.legacy"
            android:required="false" />
    </application>

</manifest>