text from a URL in to a textView crashes app using Android Studio/Kotlin

Question

I'm very new to learning Android Studio, I'm currently testing reading a json (or any text really) from a URL and displaying it in a textView. However, just having the folowing 1 line and nothing else in the function causes the app to close. Any help or pointers would be much appreciated

Activity_main has a button with onclick of "go"

I've tried this on 2 VMs (marshmallow and Q) and 2 real phones, Nougat and Pie. MainActivity.kt has the following code:

package com.name.readremotejson

import android.os.Bundle
import android.view.View
import androidx.appcompat.app.AppCompatActivity
import kotlinx.android.synthetic.main.activity_main.*
import java.net.URL

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
    }

    fun go(view:View){
       val apiResponse = URL("http://date.jsontest.com/").readText()
       // textView.text = apiResponse
    }


}

I've followed some tutorials, it says to use view:View because the button is in a view so the function needs to know it's being called from there, I still don't understand this bit and I've been looking for what they mean.

logcat errors:

2019-07-21 12:03:44.855 24631-24631/com.macemedia.readremotejson E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.macemedia.readremotejson, PID: 24631
    java.lang.IllegalStateException: Could not execute method for android:onClick
        at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:390)
        at android.view.View.performClick(View.java:6597)
        at android.view.View.performClickInternal(View.java:6574)
        at android.view.View.access$3100(View.java:778)
        at android.view.View$PerformClick.run(View.java:25885)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6718)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
     Caused by: java.lang.reflect.InvocationTargetException
        at java.lang.reflect.Method.invoke(Native Method)
        at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:385)
        at android.view.View.performClick(View.java:6597) 
        at android.view.View.performClickInternal(View.java:6574) 
        at android.view.View.access$3100(View.java:778) 
        at android.view.View$PerformClick.run(View.java:25885) 
        at android.os.Handler.handleCallback(Handler.java:873) 
        at android.os.Handler.dispatchMessage(Handler.java:99) 
        at android.os.Looper.loop(Looper.java:193) 
        at android.app.ActivityThread.main(ActivityThread.java:6718) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858) 
     Caused by: android.os.NetworkOnMainThreadException
        at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1513)
        at java.net.Inet6AddressImpl.lookupHostByName(Inet6AddressImpl.java:117)
        at java.net.Inet6AddressImpl.lookupAllHostAddr(Inet6AddressImpl.java:105)
        at java.net.InetAddress.getAllByName(InetAddress.java:1154)
        at com.android.okhttp.Dns$1.lookup(Dns.java:39)
        at com.android.okhttp.internal.http.RouteSelector.resetNextInetSocketAddress(RouteSelector.java:175)
        at com.android.okhttp.internal.http.RouteSelector.nextProxy(RouteSelector.java:141)
        at com.android.okhttp.internal.http.RouteSelector.next(RouteSelector.java:83)
        at com.android.okhttp.internal.http.StreamAllocation.findConnection(StreamAllocation.java:174)
        at com.android.okhttp.internal.http.StreamAllocation.findHealthyConnection(StreamAllocation.java:126)
        at com.android.okhttp.internal.http.StreamAllocation.newStream(StreamAllocation.java:95)
        at com.android.okhttp.internal.http.HttpEngine.connect(HttpEngine.java:281)
        at com.android.okhttp.internal.http.HttpEngine.sendRequest(HttpEngine.java:224)
        at com.android.okhttp.internal.huc.HttpURLConnectionImpl.execute(HttpURLConnectionImpl.java:461)
        at com.android.okhttp.internal.huc.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:407)
        at com.android.okhttp.internal.huc.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:244)
        at java.net.URL.openStream(URL.java:1072)
        at kotlin.io.TextStreamsKt.readBytes(ReadWrite.kt:150)
        at com.macemedia.readremotejson.MainActivity.go(MainActivity.kt:16)
        at java.lang.reflect.Method.invoke(Native Method) 
        at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:385) 
        at android.view.View.performClick(View.java:6597) 
        at android.view.View.performClickInternal(View.java:6574) 
        at android.view.View.access$3100(View.java:778) 
        at android.view.View$PerformClick.run(View.java:25885) 
        at android.os.Handler.handleCallback(Handler.java:873) 
        at android.os.Handler.dispatchMessage(Handler.java:99) 
        at android.os.Looper.loop(Looper.java:193) 
        at android.app.ActivityThread.main(ActivityThread.java:6718) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)

xml:

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">
    <TextView
            android:layout_width="0dp"
            android:layout_height="0dp"
            android:id="@+id/textView" android:layout_marginTop="16dp"
            android:layout_marginBottom="24dp" app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintBottom_toTopOf="@+id/button" app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            android:layout_marginStart="16dp" android:layout_marginEnd="16dp"/>
    <Button
            android:text="Populate"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/button" android:onClick="go"
            app:layout_constraintTop_toBottomOf="@+id/textView" android:layout_marginBottom="224dp"
            app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintBottom_toBottomOf="parent"/>
</androidx.constraintlayout.widget.ConstraintLayout>

Manifest:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
          package="com.macemedia.readremotejson">

    <application
            android:allowBackup="true"
            android:icon="@mipmap/ic_launcher"
            android:label="@string/app_name"
            android:roundIcon="@mipmap/ic_launcher_round"
            android:supportsRtl="true"
            android:usesCleartextTraffic="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>
    </application>
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

</manifest>

I forgot to add my logcat but have added it now, it means nothing to me :( — Maff, Jul 21 '19 at 10:47
this post is the answer to my solution: https://stackoverflow.com/questions/47971972/how-to-properly-use-the-url-with-kotlin-android — Maff, Jul 21 '19 at 11:49

Chrisvin Jem · Answer 1 · 2019-07-21T10:48:05.550

-1

You're using textView when you should be using view, (i.e - the variable you get from the function is named "view", not "textView")

fun go(view:View){
       val apiResponse = URL("http://date.jsontest.com/").readText()
       // textView.text = apiResponse
       (view as TextView).text = apiResponse
    }

edited Jul 21 '19 at 10:48

answered Jul 21 '19 at 10:36

Chrisvin Jem

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Hi Chrisvn, the text box has an ID of textView, however, even if the only line in the function is the URL readText then it crashes the app, there seems to be something wrong with that line. If I use the line you say then the word "text" is red and it says ""Unresolved reference: text – Maff Jul 21 '19 at 10:40
Oh right, I forgot that `text` doesn't exist in `View`. I've updated my answer, If that doesn't work, then add your xml code to the question. If it does work, then mark as correct and upvote. Cheers. – Chrisvin Jem Jul 21 '19 at 10:47

text from a URL in to a textView crashes app using Android Studio/Kotlin

1 Answers1