Error with my HttpUrlConnection trying to Write then Read

Question

This is where my HttpURLConnection is being held. I am trying to send the username/password over to my php control, which returns a true/false result.

However when I added Buffered Reader I kept getting the same error over and over.

I have seen this post, but I still don't understand. Can someone explain why this doesn't work?

METHOD:

public boolean checkLogin(String username, String password){
    boolean is_Correct = false;
    try {
        URL url = new URL(this.url);
        HttpURLConnection conn = (HttpURLConnection)url.openConnection();
        conn.setRequestMethod("POST");
        conn.setDoOutput(true);
        conn.setDoInput(true);
        conn.setUseCaches(false);
        BufferedWriter output = new BufferedWriter(new OutputStreamWriter(conn.getOutputStream(),"UTF-8"));
        output.write("func=Login");
        output.write("username="+username);
        output.write("password="+password);
        BufferedReader input = new BufferedReader(new InputStreamReader(conn.getInputStream(),"UTF-8"));
        String result = input.readLine();
        output.flush();
        output.close();
    }catch(Exception e){
        e.printStackTrace();
    }
    return is_Correct;
}

ERROR:

09-19 12:25:27.408 3913-3913/com.project.backgroundprocesstest W/System.err: android.os.NetworkOnMainThreadException
09-19 12:25:27.410 3913-3913/com.project.backgroundprocesstest W/System.err:     at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1273)
09-19 12:25:27.410 3913-3913/com.project.backgroundprocesstest W/System.err:     at java.net.InetAddress.lookupHostByName(InetAddress.java:436)
09-19 12:25:27.410 3913-3913/com.project.backgroundprocesstest W/System.err:     at java.net.InetAddress.getAllByNameImpl(InetAddress.java:252)
09-19 12:25:27.410 3913-3913/com.project.backgroundprocesstest W/System.err:     at java.net.InetAddress.getAllByName(InetAddress.java:215)
09-19 12:25:27.410 3913-3913/com.project.backgroundprocesstest W/System.err:     at com.android.okhttp.internal.Network$1.resolveInetAddresses(Network.java:29)
09-19 12:25:27.410 3913-3913/com.project.backgroundprocesstest W/System.err:     at com.android.okhttp.internal.http.RouteSelector.resetNextInetSocketAddress(RouteSelector.java:188)
09-19 12:25:27.410 3913-3913/com.project.backgroundprocesstest W/System.err:     at com.android.okhttp.internal.http.RouteSelector.nextProxy(RouteSelector.java:157)
09-19 12:25:27.410 3913-3913/com.project.backgroundprocesstest W/System.err:     at com.android.okhttp.internal.http.RouteSelector.next(RouteSelector.java:100)
09-19 12:25:27.410 3913-3913/com.project.backgroundprocesstest W/System.err:     at com.android.okhttp.internal.http.HttpEngine.createNextConnection(HttpEngine.java:399)
09-19 12:25:27.410 3913-3913/com.project.backgroundprocesstest W/System.err:     at com.android.okhttp.internal.http.HttpEngine.nextConnection(HttpEngine.java:379)
09-19 12:25:27.410 3913-3913/com.project.backgroundprocesstest W/System.err:     at com.android.okhttp.internal.http.HttpEngine.connect(HttpEngine.java:369)
09-19 12:25:27.410 3913-3913/com.project.backgroundprocesstest W/System.err:     at com.android.okhttp.internal.http.HttpEngine.sendRequest(HttpEngine.java:287)
09-19 12:25:27.410 3913-3913/com.project.backgroundprocesstest W/System.err:     at com.android.okhttp.internal.huc.HttpURLConnectionImpl.execute(HttpURLConnectionImpl.java:457)
09-19 12:25:27.410 3913-3913/com.project.backgroundprocesstest W/System.err:     at com.android.okhttp.internal.huc.HttpURLConnectionImpl.connect(HttpURLConnectionImpl.java:130)
09-19 12:25:27.410 3913-3913/com.project.backgroundprocesstest W/System.err:     at com.android.okhttp.internal.huc.HttpURLConnectionImpl.getOutputStream(HttpURLConnectionImpl.java:261)
09-19 12:25:27.410 3913-3913/com.project.backgroundprocesstest W/System.err:     at com.project.backgroundprocesstest.HttpConnect$override.checkLogin(HttpConnect.java:38)
09-19 12:25:27.410 3913-3913/com.project.backgroundprocesstest W/System.err:     at com.project.backgroundprocesstest.HttpConnect$override.access$dispatch(HttpConnect.java)
09-19 12:25:27.410 3913-3913/com.project.backgroundprocesstest W/System.err:     at com.project.backgroundprocesstest.HttpConnect.checkLogin(HttpConnect.java:0)
09-19 12:25:27.410 3913-3913/com.project.backgroundprocesstest W/System.err:     at com.project.backgroundprocesstest.LoginControl.checkLogin(LoginControl.java:13)
09-19 12:25:27.410 3913-3913/com.project.backgroundprocesstest W/System.err:     at com.project.backgroundprocesstest.MainActivity$1$override.onClick(MainActivity.java:52)
09-19 12:25:27.411 3913-3913/com.project.backgroundprocesstest W/System.err:     at com.project.backgroundprocesstest.MainActivity$1$override.access$dispatch(MainActivity.java)
09-19 12:25:27.411 3913-3913/com.project.backgroundprocesstest W/System.err:     at com.project.backgroundprocesstest.MainActivity$1.onClick(MainActivity.java:0)
09-19 12:25:27.411 3913-3913/com.project.backgroundprocesstest W/System.err:     at android.view.View.performClick(View.java:5210)
09-19 12:25:27.411 3913-3913/com.project.backgroundprocesstest W/System.err:     at android.view.View$PerformClick.run(View.java:21328)
09-19 12:25:27.411 3913-3913/com.project.backgroundprocesstest W/System.err:     at android.os.Handler.handleCallback(Handler.java:739)
09-19 12:25:27.411 3913-3913/com.project.backgroundprocesstest W/System.err:     at android.os.Handler.dispatchMessage(Handler.java:95)
09-19 12:25:27.411 3913-3913/com.project.backgroundprocesstest W/System.err:     at android.os.Looper.loop(Looper.java:148)
09-19 12:25:27.411 3913-3913/com.project.backgroundprocesstest W/System.err:     at android.app.ActivityThread.main(ActivityThread.java:5551)
09-19 12:25:27.411 3913-3913/com.project.backgroundprocesstest W/System.err:     at java.lang.reflect.Method.invoke(Native Method)
09-19 12:25:27.411 3913-3913/com.project.backgroundprocesstest W/System.err:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:730)
09-19 12:25:27.411 3913-3913/com.project.backgroundprocesstest W/System.err:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:620)
09-19 12:25:27.411 3913-3913/com.project.backgroundprocesstest

Possible duplicate of [How to fix android.os.NetworkOnMainThreadException?](http://stackoverflow.com/questions/6343166/how-to-fix-android-os-networkonmainthreadexception) — K Neeraj Lal, Sep 19 '16 at 10:41
`output.write("username="+username);`. That should be `output.write("&username="+username);`. Like for the following. — greenapps, Sep 19 '16 at 10:49
`which returns a true/false result.` Php can not return boolean values. Moreover your script is not reached at all at the moment. — greenapps, Sep 19 '16 at 10:51
Also, I don't see anywhere where you are actually checking the result. Your 'result' variable is a String that you never use... and your function returns a boolean that you never set. — Nerdy Bunz, Sep 19 '16 at 10:53
@greenapps You were right. I change it into one line and it worked. I also forgot to add the StrickMode.ThreadPolicy (the fault of the error). — atanti, Sep 19 '16 at 11:18
@BooberBunz It had nothing to do with the error, that was just incomplete code. — atanti, Sep 19 '16 at 11:18
`I also forgot to add the StrickMode.ThreadPolicy`. DO NOT USE THAT!. Put your code in an AsyncTask or Thread instead. As Boober Bunz already told you. — greenapps, Sep 19 '16 at 11:55

Nerdy Bunz · Accepted Answer · 2016-09-19T12:06:36.653

As has been mentioned, you need to use asynctask. Inside that asynctask, you could also improve your communication with your php by putting your parameters in a HashMap and using a method like this:

public String performPostCall(String requestURL, HashMap<String, String> postDataParams)
{
    String response = "Network Error.";

   // Log.i(TAG, "performpostcall was run!! yay!");
    try
    {
        URL url = new URL(requestURL);

        HttpURLConnection conn = (HttpURLConnection)url.openConnection();
        conn.setReadTimeout(8000);
        conn.setConnectTimeout(8000);
        conn.setRequestMethod("POST");
        conn.setDoInput(true);
        conn.setDoOutput(true);

        OutputStream os = conn.getOutputStream();
        BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(os, "UTF-8"));

        writer.write(getPostDataString(postDataParams));

      //  Log.i(TAG, "getPostDataString() returned " + getPostDataString(postDataParams));

        writer.flush();
        writer.close();
        os.close();

        int responseCode = conn.getResponseCode();
        if (responseCode == 200)
        {
            BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
            String line;
            while ((line = br.readLine()) != null) {
                response = response + line;
            }
        }
        else
        {
            response = "response code: " + responseCode;

        }
        conn.disconnect();
    }
    catch (Exception e)
    {
        //  This should never happen. :)
    }
    return response;
}

and...

private String getPostDataString(HashMap<String, String> params)
        throws UnsupportedEncodingException
{
    StringBuilder result = new StringBuilder();
    boolean first = true;

   // Log.i(TAG, "get PostDataString was run!! yay!");
    for (Map.Entry<String, String> entry : params.entrySet())
    {
        if (first) {
            first = false;
        } else {
            result.append("&");
        }
        result.append(URLEncoder.encode((String)entry.getKey(), "UTF-8"));
        result.append("=");
        result.append(URLEncoder.encode((String)entry.getValue(), "UTF-8"));
    }
    return result.toString();
}

This way you can control your timeouts, set your parameters easily, and get more detailed information about the causes of any errors.

Error with my HttpUrlConnection trying to Write then Read

1 Answers1