Android

8-Sep-14 0:17

I am using FragmentTabHost in xamarin C# and i get error in :

mTabHost.AddTab(spec);

and the whole project is :(Part that you may need)

Activity 2.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
 
 
using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using Android.Content.PM;
using Android.Support.V4.App;
 
 
namespace ANRestaurant.Forms
{
    [Activity(Label = "ANRestaurant", MainLauncher = true, Icon = "@drawable/icon", ScreenOrientation = ScreenOrientation.Portrait)]
 
 
    public class Activity2 : FragmentActivity
    {
        FragmentTabHost mTabHost;
        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);
 
 
            SetContentView(Resource.Layout.activity_main);
            try
            {
                mTabHost = FindViewById<FragmentTabHost>(Resource.Id.tabhostN  );
                Intent intent;
                intent = new Intent(this, typeof(Fragment1));
                intent.AddFlags(ActivityFlags.NewTask);
                //mTabHost.Setup(this, SupportFragmentManager, Resource.Id.tabFrameLayout);
 
 
                TabHost.TabSpec spec;
                spec = mTabHost.NewTabSpec("artists");
                spec.SetIndicator("Artists", Resources.GetDrawable(Resource.Drawable.tab_icon1)  );
                spec.SetContent(intent);
                mTabHost.AddTab(spec);   <code><big>======>Here the error occered!</big></code> 
                //mTabHost.AddTab(
                //        mTabHost.NewTabSpec("tab2").SetIndicator("Tab 2", null),
                //       intent, null);
                //mTabHost.addTab(
                //        mTabHost.newTabSpec("tab2").setIndicator("Tab 2", null),
                //        FragmentTab.class, null);
                //mTabHost.addTab(
                //        mTabHost.newTabSpec("tab3").setIndicator("Tab 3", null),
                //        FragmentTab.class, null);
            }
            catch (Exception ex)
            {
 
 
            }
        }
    }
}

activity_main.axml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.app.FragmentTabHost xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/tabhostN"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">
        <TabWidget
            android:id="@+id/tabs"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_weight="0"
            android:orientation="horizontal" />
        <FrameLayout
            android:id="@+id/tabFrameLayout"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1" />
    </LinearLayout>
</android.support.v4.app.FragmentTabHost>

Fragment1.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
 
 
using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Util;
using Android.Views;
using Android.Widget;
 
 
namespace ANRestaurant.Forms
{
    public class Fragment1 : Fragment
    {
 
 
        
        public override void OnCreate(Bundle savedInstanceState)
        {
            base.OnCreate(savedInstanceState);
 
 
            // Create your fragment here
        }
        public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
        {
            View view = inflater.Inflate(Resource.Layout.fragment1, container, false);
           return view;
             //return base.OnCreateView(inflater, container, savedInstanceState);
        }
    }
}

fragment1.axml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#AA1111">
    <TextView
        android:id="@+id/txtF"
        android:layout_height="wrap_content"
        android:layout_width="wrap_content"
        android:text="This is Tab 1"
        android:textSize="20sp"
        android:textColor="#dddddd"
        android:layout_centerInParent="true" />
</RelativeLayout>

<big>And THE ERROR IS :</big>

{Java.Lang.NullPointerException: Exception of type 'Java.Lang.NullPointerException' was thrown.
  at Android.Runtime.JNIEnv.CallVoidMethod (IntPtr jobject, IntPtr jmethod, Android.Runtime.JValue[] parms) [0x00063] in /Users/builder/data/lanes/monodroid-mlion-monodroid-4.12-series/98634deb/source/monodroid/src/Mono.Android/src/Runtime/JNIEnv.g.cs:507 
  at Android.Widget.TabHost.AddTab (Android.Widget.TabSpec tabSpec) [0x00043] in /Users/builder/data/lanes/monodroid-mlion-monodroid-4.12-series/98634deb/source/monodroid/src/Mono.Android/platforms/android-12/src/generated/Android.Widget.TabHost.cs:801 
  at ANRestaurant.Forms.Activity2.OnCreate (Android.OS.Bundle bundle) [0x00079] in e:\Home\Herman resturant Android\Source\ANRestaurant\ANRestaurant\Forms\Act  ivity2.cs:39 
  --- End of managed exception stack trace ---
java.lang.NullPointerException
    at android.widget.TabHost.addTab(TabHost.java:236)
    at anrestaurant.forms.Activity2.n_onCreate(Native Method)
    at anrestaurant.forms.Activity2.onCreate(Activity2.ja  va:28)
    at android.app.Activity.performCreate(Activity.java:5  104)
    at android.app.Instrumentation.callActivityOnCreate(I  nstrumentation.java:1080)
    at android.app.ActivityThread.performLaunchActivity(A  ctivityThread.java:2144)
    at android.app.ActivityThread.handleLaunchActivity(Ac  tivityThread.java:2230)
    at android.app.ActivityThread.access$600(ActivityThre  ad.java:141)
    at android.app.ActivityThread$H.handleMessage(Activit  yThread.java:1234)
    at android.os.Handler.dispatchMessage(Handler.java:99  )
    at android.os.Looper.loop(Looper.java:137)
    at android.app.ActivityThread.main(ActivityThread.jav  a:5041)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:511)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCa  ller.run(ZygoteInit.java:793)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit  .java:560)
    at dalvik.system.NativeStart.main(Native Method)
}

modified 8-Sep-14 6:25am.

Richard MacCutchan8-Sep-14 0:58

8-Sep-14 0:58

According to my counting, the line you have marked is not line 39, as referenced in the error message. However, I suspect that the variable mTabHost has not been set to point to anything. Are you sure you get a valid reference returned in the following statement?

mTabHost = FindViewById<FragmentTabHost>(Resource.Id.tabhostN  );

jojoba208-Sep-14 3:52

8-Sep-14 3:52

first of all thanks for ur attention.

i have it in "activity_main.axml" :

<android.support.v4.app.FragmentTabHost xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/tabhostN"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

And the mTabHost isnot nulll in

mTabHost = FindViewById<FragmentTabHost>(Resource.Id.tabhostN  );

Or
Possible to give me and C# xamarin example for doing the same i have done?

any further question?

Richard MacCutchan8-Sep-14 4:48

8-Sep-14 4:48

Did you actually check the value of this variable at run time? It matters not what you write in your source code, the only way to be sure it works is to check it at the time of error. If it is not that variable that causes the error then it must be one of the others.

I also notice that you have this code within a try/catch block, but you eat the exception. This is really bad practice and leads to situations just such as this. Exceptions provide useful information, so make proper use of them.

jojoba208-Sep-14 4:55

8-Sep-14 4:55

i have used this for sample for that the catch is not complete.
at runtime the mtabHost is not null.
i have breakepoint in

mTabHost.AddTab(spec);

and the error occured in here.
thanks in advanced!

Richard MacCutchan8-Sep-14 5:03

8-Sep-14 5:03

Then you need to establish what value is causing the exception. We cannot guess it from the information you have provided.

jojoba208-Sep-14 5:16

8-Sep-14 5:16

may i give ur the whole project for downloading?
thanks in advanced!

Richard MacCutchan8-Sep-14 5:40

8-Sep-14 5:40

Sorry, no. You need to do the debugging and provide the required information.

jojoba208-Sep-14 6:54

8-Sep-14 6:54

thanks
but i have done that but cannot help!
do y have any sample ?

Richard MacCutchan8-Sep-14 7:22

8-Sep-14 7:22

Sorry, I don't use Xamarin, and that is not really the solution; if you find another sample and that one does not work, what then? If you aspire to be a developer then you really need to practice diagnosing problems, even if you need help solving them.

jojoba208-Sep-14 10:17

8-Sep-14 10:17

thanks for ur advice
But the error is exact there and i dont know how to solve that~

Richard MacCutchan8-Sep-14 20:33

8-Sep-14 20:33

I have tried to explain how: you use your debugger to step through the code and look to see what variable is not being set up correctly. You can only solve it by collecting all the information around the time of error.

jojoba209-Sep-14 3:33

9-Sep-14 3:33

Thanks i have done that!
I should change :

mTabHost.AddTab(spec);

To :

mTabHost.Setup(this, SupportFragmentManager, Resource.Id.tabFrameLayout);
mTabHost.AddTab(spec, Java.Lang.Class.FromType(typeof(Fragment1)), null);

end of story

That is all!

Richard MacCutchan9-Sep-14 5:20

print directly to printer on server (xamarin C#)

9-Sep-14 5:20

Yes, it always helps to read the documentation.

jojoba205-Sep-14 1:46

Re: print directly to printer on server (xamarin C#)

5-Sep-14 1:46

I want to add a method by which I can directly print report from the printer on local network.
my server which printer is connected to is 192.168.1.50
(my printer isnt Bluetooth OR Wifi one.)
I also have seen PrinterShare but it looks like it requires a client software running on a PC connected to the printer.
I wanna to do it directly to server which has printer connected and shared!
I got this code but no USE!!!
I wanna to do that in (xamarin C#)
try
{
Socket sock = new Socket("192.168.1.222", 9100);
PrintWriter oStream = new PrintWriter(sock.getOutputStream());
oStream.println("HI,test from Android Device");
oStream.println("\n\n\n");
oStream.close();
sock.close();
}
catch (UnknownHostException e)
{
e.printStackTrace();
}
catch (IOException e)
{
e.printStackTrace();
}

Thanks in advacned!

Richard MacCutchan5-Sep-14 2:37

Re: print directly to printer on server (xamarin C#)

5-Sep-14 2:37

jojoba20 wrote:
I got this code but no USE!!!

You need to explain why it is no use. Did you get some sort of error, and if so please edit your question and add the details.

jojoba205-Sep-14 7:22

Re: print directly to printer on server (xamarin C#)

5-Sep-14 7:22

it needs wifi printer but mine is only connected to PC(server) and the printer is shared

Richard MacCutchan5-Sep-14 7:25

Re: print directly to printer on server (xamarin C#)

5-Sep-14 7:25

jojoba20 wrote:
it needs wifi printer but mine is only connected to PC

I don't think there is a lot that we can do to help with that.

jojoba205-Sep-14 9:58

Re: print directly to printer on server (xamarin C#)

5-Sep-14 9:58

thanks for reply
do u have any example for what i wanna do?
forget what i have searched!

thnaks in advanced

Richard MacCutchan5-Sep-14 21:25

Re: print directly to printer on server (xamarin C#)

5-Sep-14 21:25

See my previous answer.

Dominic Burford15-Sep-14 2:23

Dominic Burford

15-Sep-14 2:23

Check out the article I wrote on printing from an Android app developed using Xamarin.

Printing from a Xamarin.Android Application Developed with Visual Studio[^]

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Chandru N.N29-Aug-14 3:29

Chandru N.N

29-Aug-14 3:29

how can i change to vibrate mode when screen is on and change to general when screen is on...

android

Re: how to change to vibrate mode when screen is on?

Richard MacCutchan29-Aug-14 4:14