Unknown cause of java.lang.RuntimeException

Question

When I tried to start my app which checks something with the database I have encountered irrational error. My app threw an java.lang.RuntimeException with the line: OutputStream ops = http.getOutputStream();

My code is:

 String result = "";
        String connstr = "http://myip:8080/androidlogin.php";

        try {
            URL url = new URL(connstr);
            HttpURLConnection http = (HttpURLConnection) url.openConnection();
            http.setRequestMethod("POST");
            http.setDoInput(true);
            http.setDoOutput(true);

Log.d("TAG", "1");
            OutputStream ops = http.getOutputStream();
            Log.d("TAG", "2");
            BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(ops,"UTF-8"));
            Log.d("TAG", "3");
            String data = URLEncoder.encode("user","UTF-8")+"="+URLEncoder.encode(id,"UTF-8");
            Log.d("TAG", "4");
            writer.write(data);
            writer.flush();
            writer.close();
            ops.close();

            InputStream ips = http.getInputStream();
            BufferedReader reader = new BufferedReader(new InputStreamReader(ips,"ISO-8859-1"));
            String line ="";
            while ((line = reader.readLine()) != null)
            {
                result += line;
            }
            reader.close();
            ips.close();
            http.disconnect();
            return result;

        } catch (MalformedURLException e) {
            result = e.getMessage();
        } catch (IOException e) {
            result = e.getMessage();
        }


        return result;

And my error looks like this:

2020-03-13 08:01:07.460 10633-10633/com.hu.jam E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.hu.jam, PID: 10633
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.hu.jam/com.hu.jam.MainActivity}: android.os.NetworkOnMainThreadException
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2984)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3045)
        at android.app.ActivityThread.-wrap14(ActivityThread.java)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1642)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:154)
        at android.app.ActivityThread.main(ActivityThread.java:6776)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1496)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1386)
     Caused by: android.os.NetworkOnMainThreadException

The most interesting part is that between Log 1 and error there are three interesting messages on the logcat:

2020-03-13 08:01:07.442 10633-10633/com.hu.jam D/TAG: 1
2020-03-13 08:01:07.444 10633-10633/com.hu.jam I/System.out: (HTTPLog)-Static: isSBSettingEnabled false
2020-03-13 08:01:07.444 10633-10633/com.hu.jam I/System.out: (HTTPLog)-Static: isSBSettingEnabled false
2020-03-13 08:01:07.451 10633-10633/com.hu.jam D/AndroidRuntime: Shutting down VM
2020-03-13 08:01:07.460 10633-10633/com.hu.jam E/AndroidRuntime: FATAL EXCEPTION: main

Here is a php script:

<?php
$db = "database1";
$user = $_POST["user"];
$host = "localhost";

$conn = mysqli_connect($host, "root", "", $db);
if($conn){
    echo "connected....!";
    $q= "select * from article where a_title='$user'";

    $result = mysqli_query($conn, $q);
    if(mysqli_num_rows($result) > 0){
        echo"login successfull...!";
    }else {
        echo"login failed....!";
    }

}else{
    echo"connection failed....!";
}


?>

What is the problem with my code? Everything seems to be alright with it, yet it does not work...

Can you post it as an answer with code shown because that says little — Jeremiah Mason, Mar 13 '20 at 08:08

Destroyer · Answer 1 · 2020-03-13T08:14:20.607

0

To work with network requests, it is recommended to run the code in a separate thread How to run a Runnable thread in Android at defined intervals?

Runnable r = new Runnable() {
    public void run() {
      //Put your network code here
    }
}.start();

edited Mar 13 '20 at 08:14

answered Mar 13 '20 at 08:08

Destroyer

785
8
20

can you post my code with these changes done? I'm a beginner so I don't really know what to do exactly – Jeremiah Mason Mar 13 '20 at 08:11

score 0 · Answer 2 · answered Mar 13 '20 at 08:28

First, create a new Runnable. Remember, it needs to provide a mechanism for you to get the result once complete. Also, I strongly urge you to take advantage of the try-with-Resources statement instead of explicitly closing. Something like,

public class MyLoginRunnable implements Runnable {
    private StringBuilder sb = new StringBuilder();
    private String connstr;
    private String id;

    public MyLoginRunnable(String connstr, String id) {
        this.connstr = connstr;
        this.id = id;
    }

    public String getResult() {
        return sb.toString();
    }

    @Override
    public void run() {
        try {
            URL url = new URL(connstr);
            HttpURLConnection http = (HttpURLConnection) url.openConnection();
            http.setRequestMethod("POST");
            http.setDoInput(true);
            http.setDoOutput(true);

            try (OutputStream ops = http.getOutputStream();
                    BufferedWriter writer = new BufferedWriter( //
                            new OutputStreamWriter(ops, "UTF-8"))) {
                String data = URLEncoder.encode("user", "UTF-8") //
                        + "=" + URLEncoder.encode(id, "UTF-8");
                writer.write(data);
            }

            try (InputStream ips = http.getInputStream();
                    BufferedReader reader = new BufferedReader( //
                            new InputStreamReader(ips, "ISO-8859-1"))) {
                String line = "";
                while ((line = reader.readLine()) != null) {
                    sb.append(line).append(System.lineSeparator());
                }
            }
            http.disconnect();
        } catch (MalformedURLException e) {
            sb.append(e.getMessage());
        } catch (IOException e) {
            sb.append(e.getMessage());
        }
    }
}

Then you can use it like

String connstr = "http://myip:8080/androidlogin.php";
MyLoginRunnable mlr = new MyLoginRunnable(connstr, "");
Thread t = new Thread(mlr);
t.start();
try {
    t.join(); // <-- this is for your simple example, in real code you don't want to pause
} catch (InterruptedException e) {
    e.printStackTrace();
}
String result = mlr.getResult();

Well I used your code and when I Logged.d the result it gave me "Connection refused" — Jeremiah Mason, Mar 13 '20 at 09:37
@PozeraczSloikow Sounds like the server isn't working correctly at `http://myip:8080/androidlogin.php` — Elliott Frisch, Mar 13 '20 at 11:11
Well everything seems to be alright with androidlogin.php but I've posted it anyways for you by editing my question. BTW script is running on XAMPP. — Jeremiah Mason, Mar 13 '20 at 13:48
No. "Connection refused" has a pretty clear meaning. I can't help further, because I can't reproduce your environment. You need to make sure your connection string is correct. But again, connection refused means the **other** side refused the connection. — Elliott Frisch, Mar 13 '20 at 22:46

score 0 · Answer 3 · answered Mar 13 '20 at 08:43

0

The exceptiin is because you are running a Network task which is supposed to be a background task, on the main UI thread. Use AsyncTask for Networking or IO tasks. https://developer.android.com/reference/android/os/AsyncTask

answered Mar 13 '20 at 08:43

Naung9

209
1
8

Unknown cause of java.lang.RuntimeException

3 Answers3