OkHttp interceptors in Android Kotlin - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ ui_behavior

intermediate

What happens when an OkHttp interceptor modifies the request URL?

Consider an OkHttp interceptor that changes the request URL before proceeding. What will the server receive?

Android Kotlin

val interceptor = Interceptor { chain ->
  val newRequest = chain.request().newBuilder()
    .url("https://api.example.com/modified")
    .build()
  chain.proceed(newRequest)
}

A The server receives the original URL from the request before modification.

B The request fails because the URL cannot be changed in an interceptor.

C The server receives the modified URL set by the interceptor.

D The interceptor causes an infinite loop and the request never completes.

💡 Hint

Think about what the interceptor does before calling proceed.

Interceptors can modify the request before sending it. Changing the URL in the interceptor means the server gets the new URL.

❓ lifecycle

intermediate

When is an OkHttp interceptor called during a request?

At what point in the OkHttp request lifecycle does an interceptor run?

A Only after the response is received, never before the request.

B After the response is received but before it is returned to the caller.

C Only before the request is sent, never after the response.

D Before the request is sent and after the response is received, wrapping the entire call.

💡 Hint

Interceptors can modify both request and response.

OkHttp interceptors wrap the entire call, so they run before sending the request and after receiving the response.

🔧 Debug

advanced

Why does this interceptor cause a stack overflow error?

Analyze the following interceptor code. Why does it cause a stack overflow?

Android Kotlin

val interceptor = Interceptor { chain ->
  val request = chain.request()
  chain.proceed(request)
  chain.proceed(request)
}

A Calling chain.proceed(request) twice causes infinite recursion leading to stack overflow.

B The interceptor modifies the request incorrectly causing a stack overflow.

C The interceptor does not call proceed, so the request never completes causing stack overflow.

D The interceptor uses a wrong request object causing stack overflow.

💡 Hint

Check how many times proceed is called.

Calling chain.proceed(request) twice causes the interceptor to recursively call itself repeatedly, causing stack overflow.

🧠 Conceptual

advanced

What is the difference between application and network interceptors in OkHttp?

Choose the correct distinction between application interceptors and network interceptors.

A Application interceptors observe the full request and response, including retries; network interceptors see data just before network transmission.

B Network interceptors run before application interceptors and can modify the UI directly.

C Application interceptors only modify responses; network interceptors only modify requests.

D There is no difference; both interceptors behave identically.

💡 Hint

Think about when retries and caching happen.

Application interceptors see the entire request/response lifecycle including retries and caching. Network interceptors see data just before it goes on the network.

📝 Syntax

expert

What error does this interceptor code produce?

Examine the Kotlin interceptor code below. What error will it cause?

Android Kotlin

val interceptor = Interceptor { chain ->
  val request = chain.request()
  val response = chain.proceed(request)
  return response
  println("Intercepted")
}

A Compilation error due to missing semicolon after return statement.

B SyntaxError: 'return' cannot be used inside lambda expressions.

C No error; code runs and prints "Intercepted" after returning response.

D RuntimeException because println is unreachable code after return.

💡 Hint

Consider Kotlin lambda expression rules for return statements.

In Kotlin lambdas, 'return' without label tries to return from the enclosing function, which is not allowed here, causing a syntax error.