gistfile1.txt

package com.vogella.android.github.issuetracker;

import java.util.List;

import io.reactivex.android.schedulers.AndroidSchedulers;
import io.reactivex.observers.DisposableSingleObserver;
import io.reactivex.schedulers.Schedulers;
import okhttp3.Credentials;
import okhttp3.OkHttpClient;
import okhttp3.logging.HttpLoggingInterceptor;
import retrofit2.Retrofit;
import retrofit2.adapter.rxjava2.RxJava2CallAdapterFactory;
import retrofit2.converter.gson.GsonConverterFactory;

public class CommunicationController {

    private GithubApi githubApi;

    public CommunicationController() {
        initGithubApi();
    }

    private void initGithubApi() {
        HttpLoggingInterceptor interceptor = new HttpLoggingInterceptor();
        interceptor.setLevel(HttpLoggingInterceptor.Level.BODY);
        OkHttpClient okHttpClient = new OkHttpClient.Builder().addInterceptor(interceptor).build();
        Retrofit retrofit = new Retrofit.Builder()
                .client(okHttpClient)
                .baseUrl(GithubApi.BASE_URL)
                .addConverterFactory(GsonConverterFactory.create())
                .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
                .build();

        githubApi = retrofit.create(GithubApi.class);
    }

    public void loadIssues(String username, String password, DisposableSingleObserver<List<Issue>> observer, String owner, String repository) {
        githubApi.getIssues(Credentials.basic(username, password), owner, repository)
                .subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(observer);
    }
}

MainActivity

package com.vogella.android.github.issuetracker;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.KeyEvent;
import android.view.Menu;
import android.view.MenuItem;
import android.view.inputmethod.EditorInfo;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import java.util.List;


public class MainActivity extends AppCompatActivity implements CredentialsDialog.ICredentialsDialogListener {

    EditText ownerEditText;
    EditText repositoryEditText;
    TextView issuesTextView;
    private String password = "";
    private String username = "";
    private CommunicationController communicationController;
    DisposableSingleObserver<List<Issue>> issuesObserver;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.my_toolbar);
        setSupportActionBar(toolbar);

        ownerEditText = (EditText) findViewById(R.id.owner_edittext);
        repositoryEditText = (EditText) findViewById(R.id.repository_edittext);
        repositoryEditText.setOnEditorActionListener(new TextView.OnEditorActionListener() {
            @Override
            public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
                if (actionId == EditorInfo.IME_ACTION_DONE) {
                    queryForIssues();
                    return true;
                }
                return false;
            }
        });
        issuesTextView = (TextView) findViewById(R.id.issues_text);

        communicationController = new CommunicationController();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.menu_credentials:
                showCredentialsDialog();
                return true;
            case R.id.menu_refresh:
                queryForIssues();
                return true;
        }
        return super.onOptionsItemSelected(item);
    }

    private DisposableSingleObserver<List<Issue>> getIssuesObserver() {
        return new DisposableSingleObserver<List<Issue>>() {
            @Override
            public void onSuccess(List<Issue> issues) {
                for (Issue issue : issues) {
                    issuesTextView.append(issue.toString() + "\n");
                }
            }

            @Override
            public void onError(Throwable e) {
                Toast.makeText(MainActivity.this, e.getMessage(), Toast.LENGTH_SHORT).show();
            }
        };
    }

    private void showCredentialsDialog() {
        CredentialsDialog dialog = new CredentialsDialog();
        Bundle arguments = new Bundle();
        arguments.putString("username", username);
        arguments.putString("password", password);
        dialog.setArguments(arguments);

        dialog.show(getSupportFragmentManager(), "credentialsDialog");
    }

    @Override
    public void onDialogPositiveClick(String username, String password) {
        this.username = username;
        this.password = password;
    }

    private void queryForIssues() {
        issuesTextView.setText("");
        String owner = ownerEditText.getText().toString();
        String repository = repositoryEditText.getText().toString();
        
        if (username.isEmpty() || password.isEmpty()) {
            Toast.makeText(MainActivity.this, "Please provide your credentials", Toast.LENGTH_SHORT).show();
            return;
        }

        if (owner.isEmpty() || repository.isEmpty()) {
            Toast.makeText(MainActivity.this, "Please provider repository owner and/or name", Toast.LENGTH_SHORT).show();
            return;
        }

        issuesObserver = getIssuesObserver();
        communicationController.loadIssues(username, password, issuesObserver , owner, repository);
    
    }
    
    @Override
    protected void onStop() {
        super.onStop();
        if (issuesObserver!=null && !issuesObserver.isDisposed()) {
            issuesObserver.dispose();
        }
    }
}