Início Rápido: Sua primeira transação

import androidx.activity.result.ActivityResultLauncher;
import androidx.activity.result.contract.ActivityResultContracts;
import android.content.Intent;
import android.app.Activity;

public class MainActivity extends AppCompatActivity {

    private ActivityResultLauncher<Intent> paymentLauncher;

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

        // Register the Activity Result Launcher
        paymentLauncher = registerForActivityResult(
            new ActivityResultContracts.StartActivityForResult(),
            result -> {
                if (result.getResultCode() == Activity.RESULT_OK) {
                    // Payment successful
                    Intent data = result.getData();
                    if (data != null) {
                        String authNumber = data.getStringExtra("AUTHORIZATION_NUMBER");
                        String order = data.getStringExtra("ORDER");

                        // Display success message to user
                        Toast.makeText(this,
                            "Payment Successful! Auth: " + authNumber,
                            Toast.LENGTH_LONG).show();
                    }
                } else if (result.getResultCode() == Activity.RESULT_CANCELED) {
                    // Payment failed or cancelled
                    Intent data = result.getData();
                    if (data != null) {
                        String errorMsg = data.getStringExtra("ERROR_MSG");
                        String state = data.getStringExtra("STATE");

                        // Display error message to user
                        Toast.makeText(this,
                            "Payment Failed: " + errorMsg,
                            Toast.LENGTH_LONG).show();
                    }
                }
            }
        );
    }
}

private void processPayment(double amount, String invoiceNumber) {
    // Create the payment Intent
    Intent paymentIntent = new Intent("es.redsys.paysys.mPOSRedsys_PAYMENT_REQUEST");

    // Add required parameters
    paymentIntent.putExtra("amount", amount);
    paymentIntent.putExtra("invoice", invoiceNumber);

    try {
        // Launch the Get Mini application
        paymentLauncher.launch(paymentIntent);
    } catch (ActivityNotFoundException e) {
        // Handle case where Get Mini app is not installed
        showInstallDialog();
    }
}

private void showInstallDialog() {
    String playStoreUrl = "[https://play.google.com/store/apps/details?id=es.android.redsys.Get](https://play.google.com/store/apps/details?id=es.android.redsys.Get) Mini.movil";

    new AlertDialog.Builder(this)
        .setTitle("Get Mini Not Found")
        .setMessage("The Get Mini app must be installed to process payments.")
        .setPositiveButton("Install", (dialog, which) -> {
            Intent intent = new Intent(Intent.ACTION_VIEW);
            intent.setData(Uri.parse(playStoreUrl));
            startActivity(intent);
        })
        .setNegativeButton("Cancel", null)
        .show();
}

// Example: Process a payment of €10.50 with invoice number "ORD-12345"
Button payButton = findViewById(R.id.pay_button);
payButton.setOnClickListener(v -> {
    processPayment(10.50, "ORD-12345");
});