fixing lifecycle activity

app/src/main/java/com/example/yourcashiertest/activities/CartActivity.java

@@ -61,31 +61,21 @@ public class CartActivity extends AppCompatActivity {
         });
 
 
-        btnMin.setOnClickListener(new View.OnClickListener() {
-            @Override
-            public void onClick(View view) {
+        btnMin.setOnClickListener(view -> {
             count--;
             if (count == 0){
 
             }
             pricePerQty = price * count;
             changeOnClick(count, pricePerQty, totalPrice);
-            }
         });
 
 
-        btnBack.setOnClickListener(new View.OnClickListener() {
-            @Override
-            public void onClick(View view) {
-                startActivity(new Intent(CartActivity.this, MainActivity.class));
-            }
-        });
+        btnBack.setOnClickListener(view -> startActivity(new Intent(CartActivity.this, MainActivity.class)));
 
-        btnCheckout.setOnClickListener(new View.OnClickListener() {
-            @Override
-            public void onClick(View view) {
+        btnCheckout.setOnClickListener(view -> {
             startActivity(new Intent(CartActivity.this, PaymentActivity.class));
-            }
+            finish();
         });
     }
 

app/src/main/java/com/example/yourcashiertest/activities/MainActivity.java

@@ -4,7 +4,6 @@ import androidx.annotation.NonNull;
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.databinding.DataBindingUtil;
 import androidx.lifecycle.ViewModelProvider;
-import androidx.recyclerview.widget.GridLayoutManager;
 
 import android.Manifest;