java.lang.ClassNotFoundException: Didn't find class "retrofit2.Callback" on path: DexPathList

[700brains]

Got this error when i have entered valid card details and hit pay, the app closes by itself.

E/AndroidRuntime: FATAL EXCEPTION: main
Process: team.hyperiontech.store, PID: 8380
java.lang.NoClassDefFoundError: Failed resolution of: Lretrofit2/Callback;
at co.paystack.android.Paystack.chargeCard(Paystack.java:67)
at co.paystack.android.Paystack.chargeCard(Paystack.java:57)
at co.paystack.android.PaystackSdk.chargeCard(PaystackSdk.java:151)
at team.hyperiontech.store.MainActivity.performCharge(MainActivity.java:103)
at team.hyperiontech.store.MainActivity.access$1200(MainActivity.java:20)
at team.hyperiontech.store.MainActivity$1.onClick(MainActivity.java:75)
at android.view.View.performClick(View.java:5675)
at android.view.View$PerformClick.run(View.java:22641)
at android.os.Handler.handleCallback(Handler.java:836)
at android.os.Handler.dispatchMessage(Handler.java:103)
at android.os.Looper.loop(Looper.java:203)
at android.app.ActivityThread.main(ActivityThread.java:6289)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1063)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:924)
Caused by: java.lang.ClassNotFoundException: Didn't find class "retrofit2.Callback" on path: DexPathList[[zip file "/data/app/team.hyperiontech.store-1/base.apk"],nativeLibraryDirectories=[/data/app/team.hyperiontech.store-1/lib/arm, /system/lib, /vendor/lib, /system/vendor/lib]]
at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
at java.lang.ClassLoader.loadClass(ClassLoader.java:380)
at java.lang.ClassLoader.loadClass(ClassLoader.java:312)
at co.paystack.android.Paystack.chargeCard(Paystack.java:67) 
at co.paystack.android.Paystack.chargeCard(Paystack.java:57) 
at co.paystack.android.PaystackSdk.chargeCard(PaystackSdk.java:151) 
at team.hyperiontech.store.MainActivity.performCharge(MainActivity.java:103) 
at team.hyperiontech.store.MainActivity.access$1200(MainActivity.java:20) 
at team.hyperiontech.store.MainActivity$1.onClick(MainActivity.java:75) 
at android.view.View.performClick(View.java:5675) 
at android.view.View$PerformClick.run(View.java:22641) 
at android.os.Handler.handleCallback(Handler.java:836) 
at android.os.Handler.dispatchMessage(Handler.java:103) 
at android.os.Looper.loop(Looper.java:203) 
at android.app.ActivityThread.main(ActivityThread.java:6289) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1063) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:924) 
Process 8380 terminated.
MainActivity:
`package team.hyperiontech.store;

import android.support.multidex.MultiDex;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import co.paystack.android.Paystack;
import co.paystack.android.PaystackSdk;
import co.paystack.android.Transaction;
import co.paystack.android.model.Card;
import co.paystack.android.model.Charge;

public class MainActivity extends AppCompatActivity {
private Card card;
private Charge charge;

private EditText emailField;
private EditText cardNumberField;
private EditText expiryMonthField;
private EditText expiryYearField;
private EditText cvvField;

private String email, cardNumber, cvv;
private int expiryMonth, expiryYear;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    MultiDex.install(this);
    //init paystack sdk1
    PaystackSdk.initialize(getApplicationContext());
    //init paystack sdk2

// App sdk = new App();
// sdk.onCreate();

    //init view
    Button payBtn = (Button) findViewById(R.id.pay_button);

    emailField = (EditText) findViewById(R.id.edit_email_address);
    cardNumberField = (EditText) findViewById(R.id.edit_card_number);
    expiryMonthField = (EditText) findViewById(R.id.edit_expiry_month);
    expiryYearField = (EditText) findViewById(R.id.edit_expiry_year);
    cvvField = (EditText) findViewById(R.id.edit_cvv);


    payBtn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            if (!validateForm()) {
                return;
            }
            try {
                email = emailField.getText().toString().trim();
                cardNumber = cardNumberField.getText().toString().trim();
                expiryMonth = Integer.parseInt(expiryMonthField.getText().toString().trim());
                expiryYear = Integer.parseInt(expiryYearField.getText().toString().trim());
                cvv = cvvField.getText().toString().trim();

                //String cardNumber = "4084084084084081";
                //int expiryMonth = 11; //any month in the future
                //int expiryYear = 18; // any year in the future
                //String cvv = "408";
                card = new Card(cardNumber, expiryMonth, expiryYear, cvv);

                if (card.isValid()) {
                    Toast.makeText(MainActivity.this, "Card is Valid", Toast.LENGTH_LONG).show();
                    performCharge();
                } else {
                    Toast.makeText(MainActivity.this, "Card not Valid", Toast.LENGTH_LONG).show();
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}


/*Method to perform the charging of the card
 */
private void performCharge() {
    //create a Charge object
    charge = new Charge();

    //set the card to charge
    charge.setCard(card);

    //call this method if you set a plan
    //charge.setPlan("PLN_yourplan");

    charge.setEmail(email); //dummy email address

    charge.setAmount(100); //test amount

    PaystackSdk.chargeCard(MainActivity.this, charge, new Paystack.TransactionCallback() {
        @Override
        public void onSuccess(Transaction transaction) {
            // This is called only after transaction is deemed successful.
            // Retrieve the transaction, and send its reference to your server
            // for verification.
            String paymentReference = transaction.getReference();
            Toast.makeText(MainActivity.this, "Transaction Successful! payment reference: "
                    + paymentReference, Toast.LENGTH_LONG).show();
        }

        @Override
        public void beforeValidate(Transaction transaction) {
            // This is called only before requesting OTP.
            // Save reference so you may send to server. If
            // error occurs with OTP, you should still verify on server.
        }

        @Override
        public void onError(Throwable error, Transaction transaction) {
            //handle error here
        }
    });
}

private boolean validateForm() {
    boolean valid = true;

    String email = emailField.getText().toString();
    if (TextUtils.isEmpty(email)) {
        emailField.setError("Required.");
        valid = false;
    } else {
        emailField.setError(null);
    }

    String cardNumber = cardNumberField.getText().toString();
    if (TextUtils.isEmpty(cardNumber)) {
        cardNumberField.setError("Required.");
        valid = false;
    } else {
        cardNumberField.setError(null);
    }


    String expiryMonth = expiryMonthField.getText().toString();
    if (TextUtils.isEmpty(expiryMonth)) {
        expiryMonthField.setError("Required.");
        valid = false;
    } else {
        expiryMonthField.setError(null);
    }

    String expiryYear = expiryYearField.getText().toString();
    if (TextUtils.isEmpty(expiryYear)) {
        expiryYearField.setError("Required.");
        valid = false;
    } else {
        expiryYearField.setError(null);
    }

    String cvv = cvvField.getText().toString();
    if (TextUtils.isEmpty(cvv)) {
        cvvField.setError("Required.");
        valid = false;
    } else {
        cvvField.setError(null);
    }

    return valid;
}

}
Manifest:


<dist:module dist:instant="true" />

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

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <meta-data
        android:name="co.paystack.android.PublicKey"
        android:value="pk_test_my_valid_test_key_here"/>
</application>

`

[chydee]

I am also facing this issue

[chydee]

Updated guys: you can fix the issue by adding
//Retrofit Dependency
implementation 'com.squareup.retrofit2:retrofit:2.6.2'
implementation 'com.squareup.retrofit2:converter-gson:2.6.2'

@opezyhick just showed me how

[tkalejaiye]

HI @chydee what file did you have to add those two lines to?

[chydee]

build.gradle (module: app) file
Inside dependencies{
....
}

[studywithlawz]

Thanks chydee

[skyestudiosDev]

I wonder why you initiate multidex inside activity onCreate?

[opezyhick]

I wonder why you initiate multidex inside activity onCreate?

Yeah ..
He should be initiated at AppActivity.....