Apuntes para Devs

Dependencias

implementation 'android.arch.lifecycle:extensions:1.1.1'

Implementación

public class PackageViewModel extends AndroidViewModel {

    private final String TAG = PackageViewModel.class.getSimpleName();

    private YouAsynctask mAsyncTask;

    private MutableLiveData<List<ApplicationInfo>> mPackagesAll;

    public PackageViewModel(@NonNull Application application) {
        super(application);
    }

    LiveData<List<ApplicationInfo>> getAllPackages() {
        if (mPackagesAll == null) {
            mPackagesAll = new MutableLiveData<>();
            loadData();
        }
        return mPackagesAll;
    }

    private void loadData() {
        mAsyncTask = new YouAsynctask();
        mAsyncTask.execute();
    }

    public class YouAsynctask extends AsyncTask<Void, Float, Boolean> {

        @Override
        protected Boolean doInBackground(Void... voids) {

            final PackageManager pm = getApplication().getPackageManager(); //get a list of installed apps.
            List<ApplicationInfo> packagesAll = pm.getInstalledApplications(PackageManager.GET_META_DATA);
            mPackagesAll.postValue(packagesAll);

            return null;
        }

        @Override
        protected void onPostExecute(Boolean aBoolean) {
            super.onPostExecute(aBoolean);
        }
    }
}

Su uso

private PackageViewModel packageViewModel;
 ...
packageViewModel = ViewModelProviders.of(this).get(PackageViewModel.class);

packageViewModel.getAllPackages().observe(this, new Observer<List<ApplicationInfo>>() {
    @Override
    public void onChanged(List<ApplicationInfo> applicationInfos) {
        Log.d(TAG, "onChanged: " + applicationInfos.size());
    }
});

Si se recibe el siguiente alerta al compilar:

Schema export directory is not provided to the annotation processor so we cannot export the schema. You can either provide `room.schemaLocation` annotation processor argument OR set exportSchema to false.

Solución:
Agregar en build.gradle añadir

javaCompileOptions {
    annotationProcessorOptions {
        arguments = ["room.schemaLocation": "$projectDir/schemas".toString()]
    }
}

Ejemplo para Java:

// ...

android {

    // ... (compileSdkVersion, buildToolsVersion, etc)

    defaultConfig {

        // ... (applicationId, miSdkVersion, etc)

        javaCompileOptions {
            annotationProcessorOptions {
                arguments = ["room.schemaLocation": "$projectDir/schemas".toString()]
            }
        }
    }

    // ... (buildTypes, compileOptions, etc)

}

// ...

Ejemplo para Kotlin

android {

    // ... (compileSdkVersion, buildToolsVersion, etc)

    defaultConfig {

     // ... (applicationId, miSdkVersion, etc)

        kapt {
            arguments {
                arg("room.schemaLocation", "$projectDir/schemas".toString())
            }
        }
    }

    buildTypes {
    // ... (buildTypes, compileOptions, etc)
    }
}

Si necesitas parsear el contenido de un QRCode

https://github.com/RurioLuca/QrCardParsing

Con la librería Chrome Like Tab Switcher puedes tener el componente que usa chrome para seleccionar las pestañas mediante fichas




Descarga
https://github.com/michael-rapp/ChromeLikeTabSwitcher

compile 'com.github.HotBitmapGG:RingProgressBar:V1.2.2'