Flutter- App working on emulator but not on device (uses http package)

Question

My application works fine on emulator Nexus 5 (API 28) but when i build an apk to try it on real device it doesn't, The login button does nothing at all.

I've removed all features from the app, now it just logs in through http package, it uses a php file that communicates with the Mysql database and return values in Json format.

The app logs in user and send him to another screen that says "Success"

UI part:

    child: Material(
    color: Colors.transparent,
    child: InkWell(
    onTap: () {
    Services.logIn(_usernameController.text.trim(),
    _passwordController.text.trim(), context);
    },

Services.logIn :

 static Future<bool> logIn(
      String username, String password, BuildContext context) async {
    var map = Map<String, dynamic>();
    map['action'] = _LOGIN;
    map['username'] = username;
    map['password'] = password;
    final response = await http.post(ROOT, body: map);

    if (response.body.isNotEmpty) {
      Navigator.push(
          context, MaterialPageRoute(builder: (context) => LoginSuccesed()));
      return true;
    } else {
      return false;
    }
  }

AndroidManifest:

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="manshore.apk_testing">
    <!-- io.flutter.app.FlutterApplication is an android.app.Application that
         calls FlutterMain.startInitialization(this); in its onCreate method.
         In most cases you can leave this as-is, but you if you want to provide
         additional functionality it is fine to subclass or reimplement
         FlutterApplication and put your custom class here. -->
    <application
        android:name="io.flutter.app.FlutterApplication"
        android:label="apk_testing"
        android:icon="@mipmap/ic_launcher">
        <activity
            android:name=".MainActivity"
            android:launchMode="singleTop"
            android:theme="@style/LaunchTheme"
            android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
            android:hardwareAccelerated="true"
            android:windowSoftInputMode="adjustResize">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <!-- Don't delete the meta-data below.
             This is used by the Flutter tool to generate GeneratedPluginRegistrant.java -->
        <meta-data
            android:name="flutterEmbedding"
            android:value="2" />
    </application>
</manifest>

Android > App > build.gradle (it shows error on 'Properties' and 'GradleException' cannot resolve symbole)

def localProperties = new Properties()
def localPropertiesFile = rootProject.file('local.properties')
if (localPropertiesFile.exists()) {
    localPropertiesFile.withReader('UTF-8') { reader ->
        localProperties.load(reader)
    }
}

def flutterRoot = localProperties.getProperty('flutter.sdk')
if (flutterRoot == null) {
    throw new GradleException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
}

def flutterVersionCode = localProperties.getProperty('flutter.versionCode')
if (flutterVersionCode == null) {
    flutterVersionCode = '1'
}

def flutterVersionName = localProperties.getProperty('flutter.versionName')
if (flutterVersionName == null) {
    flutterVersionName = '1.0'
}

apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"

android {
    compileSdkVersion 28

    sourceSets {
        main.java.srcDirs += 'src/main/kotlin'
    }

    lintOptions {
        disable 'InvalidPackage'
    }

    defaultConfig {
        // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
        multiDexEnabled true
        applicationId "manshore.apk_testing"
        minSdkVersion 16
        targetSdkVersion 28
        versionCode flutterVersionCode.toInteger()
        versionName flutterVersionName
        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            // TODO: Add your own signing config for the release build.
            // Signing with the debug keys for now, so `flutter run --release` works.
            signingConfig signingConfigs.debug
        }
    }
}

flutter {
    source '../..'
}

dependencies {
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'androidx.test:runner:1.1.1'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.1'
}

Full UI:

import 'package:flutter/material.dart';
import 'Services.dart';

void main() => runApp(MaterialApp(home: LoginUI()));

class LoginUI extends StatefulWidget {
  @override
  _LoginUIState createState() => new _LoginUIState();
}

class _LoginUIState extends State<LoginUI> {
  final _usernameController = TextEditingController();
  final _passwordController = TextEditingController();

  Widget build(BuildContext context) {
    return MaterialApp(
      home: new Scaffold(
        backgroundColor: Colors.white,
        resizeToAvoidBottomPadding: true,
        body: Stack(
          children: <Widget>[
            SingleChildScrollView(
              child: Column(
                children: <Widget>[
                  Container(
                    width: double.infinity,
                    child: Column(
                      crossAxisAlignment: CrossAxisAlignment.start,
                      children: <Widget>[
                        SizedBox(height: 50),
                        TextField(
                          controller: _usernameController,
                          decoration: InputDecoration(
                              hintText: "username",
                              hintStyle: TextStyle(
                                  color: Colors.grey, fontSize: 12.0)),
                        ),
                        SizedBox(),
                        TextField(
                          controller: _passwordController,
                          obscureText: true,
                          decoration: InputDecoration(
                              hintText: "Password",
                              hintStyle: TextStyle(
                                  color: Colors.grey, fontSize: 12.0)),
                        ),
                        SizedBox(),
                      ],
                    ),
                  ),
                  Row(
                    mainAxisAlignment: MainAxisAlignment.spaceBetween,
                    children: <Widget>[
                      InkWell(
                        child: Container(
                          decoration: BoxDecoration(
                              gradient: LinearGradient(colors: [
                                Color(0xFF17ead9),
                                Color(0xFF6078ea)
                              ]),
                              borderRadius: BorderRadius.circular(6.0),
                              boxShadow: [
                                BoxShadow(
                                    color: Color(0xFF6078ea).withOpacity(.3),
                                    offset: Offset(0.0, 8.0),
                                    blurRadius: 8.0)
                              ]),
                          child: Material(
                            color: Colors.transparent,
                            child: InkWell(
                              onTap: () {
                                Services.logIn(_usernameController.text.trim(),
                                    _passwordController.text.trim(), context);
                              },
                              child: Center(
                                child: Text("SIGNIN",
                                    style: TextStyle(
                                        color: Colors.white,
                                        fontFamily: "Poppins-Bold",
                                        fontSize: 18,
                                        letterSpacing: 1.0)),
                              ),
                            ),
                          ),
                        ),
                      ),
                    ],
                  ),
                  SizedBox(),
                ],
              ),
            )
          ],
        ),
      ),
    );
  }
}

Answer 1

You need internet permission in your AndroidManifest.xml file. Add following line:

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