I am new to android app developing. My app with PayPal payment sandbox
In sandbox I have no return_url defined.
Please help me out of this PayPal API mess 😉

Kotlin implementation of PayPalWebCheckoutClient

First question is how to onNewIntent?
The PayPal documentation seems not quit working:

override fun onNewIntent(newIntent: Intent?) {
        super.onNewIntent(intent)
        intent = newIntent
    }

instead I use:

override fun onNewIntent(intent: Intent) {
        super.onNewIntent(intent)
        // Pass the intent to PayPalWebCheckoutClient to handle the PayPal response
        handlePayPalRedirect(intent)
    }

private fun handlePayPalRedirect(intent: Intent?) {
        Log.d("handlePayPalRedirect","handlePayPalRedirect...")
        Toast.makeText(this@MyPaymentsActivity, "handlePayPalRedirect...", Toast.LENGTH_LONG).show()
        intent?.data?.let { uri ->
            // Process the PayPal payment result by extracting query parameters from the URI
            val queryParams = uri.queryParameterNames

            Log.d("handlePayPalRedirect","queryParams: $queryParams")

            // Continue with PayPal-specific logic
            if (queryParams.contains("opType")) {
                val opType = uri.getQueryParameter("opType")
                if (opType == "cancel") {
                    Log.d("handlePayPalRedirect", "Payment canceled by user")
                    Toast.makeText(this@MyPaymentsActivity, "Payment was canceled.", Toast.LENGTH_LONG).show()
                    finish() // Close the activity or handle accordingly
                    return
                }
            }

            if (queryParams.contains("token") && queryParams.contains("PayerID")) {
                val token = uri.getQueryParameter("token")
                val payerId = uri.getQueryParameter("PayerID")

                if (token != null && payerId != null) {
                    captureOrder(token, payerId)
                } else {
                    Log.e("handlePayPalRedirect", "Token or PayerID is null")
                }
            } else {
                Log.e("handlePayPalRedirect", "Required query parameters are missing")
            }
        }
    }

Still I don’t get into “if (opType == “cancel”)”

2. second question: always get into listener: “onPayPalWebCanceled”

Here my createOrderId function:

suspend fun createOrderId(accessToken: String): String {
        val client = OkHttpClient()

//        val amount = Constants.PAYPAL_AMOUNT

        // Your access token obtained from PayPal
        val accessToken = BuildConfig.PAYPAL_ACCESS_TOKEN

        // Request payload
        val jsonPayload = JSONObject()
            .put("intent", "CAPTURE")
            .put(
                "purchase_units", JSONArray().put(
                    JSONObject()
                        .put(
                            "amount", JSONObject()
                                .put("currency_code", "EUR")
                                .put("value", amount)
                        )
                )
            )
            .put(
                "payment_source", JSONObject()
                    .put(
                        "paypal", JSONObject()
                            .put(
                                "experience_context", JSONObject()
                                    .put("user_action", "PAY_NOW")
                                    .put("return_url", "custom-url-scheme://paypal")
                                    .put("cancel_url", "custom-url-scheme://paypal?opType=cancel")
                            )
                    )
            ).toString()

        // Build the request
        val request = Request.Builder()
            .url("https://api-m.sandbox.paypal.com/v2/checkout/orders/")
            .post(jsonPayload.toRequestBody("application/json; charset=utf-8".toMediaType()))
            .addHeader("Authorization", "Bearer $accessToken")
            .addHeader("Content-Type", "application/json")
            .build()

        return try {
            // Execute the request
            val response = client.newCall(request).execute()
            if (!response.isSuccessful) {
                throw IOException("Unexpected code $response")
            }

            // Extract the order ID from the response
            val responseBody = response.body?.string()
            val jsonResponse = JSONObject(responseBody)
            jsonResponse.getString("id") // Extract the order ID from the response
        } catch (e: Exception) {
            // Handle errors
            throw IOException("Error creating PayPal order: ${e.message}")
        }
    }

The manifest activity intent-filter:

<data android:scheme="custom-url-scheme" />

All this is from my MainActivity from a dialog:

private fun showSupportDeveloperDialog() {
        val builder = AlertDialog.Builder(this)
        val inflater = layoutInflater
        val dialogLayout = inflater.inflate(R.layout.dialog_support_developer, null)
        builder.setView(dialogLayout)
        val dialog = builder.create()

        val amountEditText: EditText = dialogLayout.findViewById(R.id.amountEditText)

        val payPalButton: PayPalButton = dialogLayout.findViewById(R.id.paypal_button)

        payPalButton.setOnClickListener {
            val amount = amountEditText.text.toString().trim().ifEmpty {
                Constants.PAYPAL_AMOUNT.toString()
            }

            // Start the MyPaymentsActivity and pass the amount
            val intent = Intent(this, MyPaymentsActivity::class.java)
            intent.putExtra("amount", amount)
            startActivity(intent)
            dialog.dismiss()
        }

building variant debug. Emulator API 30.
also apk in Xiami 12lite

In sandbox account no payment is done!