Using okhttp for simple get request in Kotlin helper class

Question

just started learning Kotlin. I'm trying to use okhttp to send a simple get request to a URL that contains only text.

I want the output of the request stored in a liveData variable, but when I run it, it crashes. Here's the class:

// gradle dependency added to build.gradle:
// implementation("com.squareup.okhttp3:okhttp:4.5.0")
//
// added this permission to AndroidManifest.xml just above the "application" section
// <uses-permission android:name="android.permission.INTERNET" />
//

import androidx.lifecycle.LiveData
import androidx.lifecycle.MutableLiveData
import okhttp3.OkHttpClient
import okhttp3.Request
import java.io.IOException



class GetExample {
    private val client = OkHttpClient()
    private val _theResult = MutableLiveData<String?>()
    val theResult: LiveData<String?> = _theResult
   

    @Throws(IOException::class)
    fun getText(url: String) {
        val request = Request.Builder().url(url).build()
        try {
            client.newCall(request).execute()
                .use { response -> _theResult.value = response.body?.string() }
        } catch (e: IOException) {
            _theResult.value = e.message
        }
    }
}

And to call this I'm using

val url = "https://raw.github.com/square/okhttp/master/README.md"
GetExample().getText(url)

and accessing the result with

var thisString: String? = GetExample().theResult.value

Help greatly appreciated

Answer 1

You are trying to execute this on the UI thread. That will not work. Just try to run it on another thread, like the IO Thread, and use postValue in liveData. Otherwise, you need to set the value on the UI thread.

E.g.,

try {
    runBlocking(IO) {
        client.newCall(request).execute()
            .use { response -> _theResult.postValue(response.body?.string()) }
    }
} catch (e: IOException) {
    _theResult.value = e.message
}