v2 API

Hi Chuck,
thank you very much for your reply and suggestion.

In the mean time, there have been a few progresses. With the attached code, I am able to start and complete the flow. Also, to store and re-use the resulting access token.
It seems to me have obtained an access token but I am not able to make a client.

Indeed, when I add the "requestConfig" setting I have the following error:-
error: cannot access OkHttpClient
class file for okhttp3.OkHttpClient not found

I hope that this time to be easer for you to help me.
But I have another issue.
When I'll have made a client, it is still not clear how may I use it.
I mean, I would like to download/upload a file from/to a Dropbox folder of mine.
Well, how can I perform it?

Thank you very much, in advance.
Kind Regards,
Andre

public class PrvDef extends AppCompatActivity {

    private static DbxClientV2 sDbxClient;
    public Button auth_but;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_prv_def);

        auth_but = (Button) findViewById(R.id.login_button);
        auth_but.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Auth.startOAuth2Authentication(PrvDef.this, getString(R.string.app_key));
            }
        });
    }


    @Override
    protected void onResume() {
        super.onResume();

        if (hasToken()) {
            findViewById(R.id.login_button).setVisibility(View.GONE);
            findViewById(R.id.email_text).setVisibility(View.VISIBLE);
            findViewById(R.id.name_text).setVisibility(View.VISIBLE);
            findViewById(R.id.type_text).setVisibility(View.VISIBLE);
            findViewById(R.id.files_button).setEnabled(true);
            findViewById(R.id.open_with).setEnabled(true);
        } else {
            findViewById(R.id.login_button).setVisibility(View.VISIBLE);
            findViewById(R.id.email_text).setVisibility(View.GONE);
            findViewById(R.id.name_text).setVisibility(View.GONE);
            findViewById(R.id.type_text).setVisibility(View.GONE);
            findViewById(R.id.files_button).setEnabled(false);
            findViewById(R.id.open_with).setEnabled(false);
        }
    }
    protected boolean hasToken() {
        SharedPreferences prefs = getSharedPreferences("dropbox-sample", MODE_PRIVATE);
        String accessToken = prefs.getString("access-token", null);
        if (accessToken == null) {
            accessToken = Auth.getOAuth2Token();
            if (accessToken != null) {
                prefs.edit().putString("access-token", accessToken).apply();
            }
        }
        //--  requestConfig setting --------------------------------------------------------
        DbxRequestConfig requestConfig = DbxRequestConfig.newBuilder("examples-v2-demo")
                .withHttpRequestor(new OkHttp3Requestor(OkHttp3Requestor.defaultOkHttpClient()))
                .build();
        sDbxClient = new DbxClientV2(requestConfig, accessToken);
        return accessToken != null;
    }

}

========================= Manifest =====================================
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.rram.prvdef">

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

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

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

        <activity
            android:name="com.dropbox.core.android.AuthActivity"
            android:configChanges="orientation|keyboard"
            android:launchMode="singleTask">
            <intent-filter>

                <!-- Change this to be db- followed by your app key -->
                <data android:scheme="db-..my app key ..." />

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

                <category android:name="android.intent.category.BROWSABLE" />
                <category android:name="android.intent.category.DEFAULT" />
            </intent-filter>
        </activity>

    </application>

</manifest>