noitse noitse - 17 days ago 7
Android Question

Android studio httpURLConnection app crash

I am new to Android and Java development , i am working as web developer and wanted to learn Android studio and java.

As always when learning new language , first thing I do is some database call, in this just JSON call.

Using httpURLConnection , i have found example online and it works in my main function when i run it in android studio, but when I put it inside button on click function and run my app on my mobile, my app crashes.

I have also added

To AndroidManifest.xml inside manifest tags.

Here is error i get

11-22 19:47:46.354 24975-24975/com.example.adis.myapp I/System.out: I am here//////////////////////////////////////////
11-22 19:47:46.494 24975-24975/com.example.adis.myapp D/AndroidRuntime: Shutting down VM
11-22 19:47:46.494 24975-24975/com.example.adis.myapp W/dalvikvm: threadid=1: thread exiting with uncaught exception (group=0x41659e00)
11-22 19:47:46.514 24975-24975/com.example.adis.myapp E/AndroidRuntime: FATAL EXCEPTION: main

Process: com.example.adis.myapp, PID: 24975
java.lang.IllegalStateException: Could not execute method for android:onClick
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293)
ive Method)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
at android.view.View.performClick(View.java:4457) 
at android.view.View$PerformClick.run(View.java:18491) 
at android.os.Handler.handleCallback(Handler.java:733) 
at android.os.Handler.dispatchMessage(Handler.java:95) 
at android.os.Looper.loop(Looper.java:136) 
at android.app.ActivityThread.main(ActivityThread.java:5333) 
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:515) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:895) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:711) 
at dalvik.system.NativeStart.main(Native Method) 
Caused by: android.os.NetworkOnMainThreadException
at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1148)
at java.net.InetAddress.lookupHostByName(InetAddress.java:385)
at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
at java.net.InetAddress.getAllByName(InetAddress.java:214)
at com.android.okhttp.internal.Dns$1.getAllByName(Dns.java:28)
at com.android.okhttp.internal.http.RouteSelector.resetNextInetSocketAddress(RouteSelector.java:216)
at com.android.okhttp.internal.http.RouteSelector.next(RouteSelector.java:122)
at com.android.okhttp.internal.http.HttpEngine.connect(HttpEngine.java:292)
at com.android.okhttp.internal.http.HttpEngine.sendSocketRequest(HttpEngine.java:255)
at com.android.okhttp.internal.http.HttpEngine.sendRequest(HttpEngine.java:206)
at com.android.okhttp.internal.http.HttpURLConnectionImpl.execute(HttpURLConnectionImpl.java:345)
at com.android.okhttp.internal.http.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:296)
at com.android.okhttp.internal.http.HttpURLConnectionImpl.getResponseCode(HttpURLConnectionImpl.java:503)
at com.example.adis.myapp.MainActivity.loginFunction(MainActivity.java:85)
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:515) 
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) 
at android.view.View.performClick(View.java:4457) 
at android.view.View$PerformClick.run(View.java:18491) 
at android.os.Handler.handleCallback(Handler.java:733) 
at android.os.Handler.dispatchMessage(Handler.java:95) 
at android.os.Looper.loop(Looper.java:136) 
at android.app.ActivityThread.main(ActivityThread.java:5333) 
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:515) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:895) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:711) 
at dalvik.system.NativeStart.main(Native Method) 
11-22 19:47:46.524 923-1275/? W/ActivityManager: Force finishing activity com.example.adis.myapp/.MainActivity


Here is my onClick function

public void loginFunction(View view) throws IOException, JSONException {


System.out.println("I am here//////////////////////////////////////////");
try {

URL url = new URL("http://echo.jsontest.com/insert-key-here/insert-value-here/key/value");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
conn.setRequestProperty("Accept", "application/json");

if (conn.getResponseCode() != 200) {
throw new RuntimeException("Failed : HTTP error code : "
+ conn.getResponseCode());
}

BufferedReader br = new BufferedReader(new InputStreamReader(
(conn.getInputStream())));

String output;
System.out.println("Output from Server .... \n");
while ((output = br.readLine()) != null) {
System.out.println(output);
}

conn.disconnect();

} catch (MalformedURLException e) {

e.printStackTrace();

} catch (IOException e) {

e.printStackTrace();

}



}


Be harsh on me if you see some stupid mistake even java beginner should see, because i don't .

Thank you for stopping by :)

Answer

You're not allowed to make a network connection on the main thread since this can freeze the UI thread and make your app unresponsive. That is why the exception is thrown.

You can make the button fire off a new thread or AsyncTask to complete the action.

Example: How to fix android.os.NetworkOnMainThreadException?