Develop Reference

Unable to start activity NullPointerException-onActivityCreated

My App crash rarely
i want to get off this bug for ever.
this is the log that users Report
i tried so long on this but nothing helps
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.xxx.xxx/com.xxx.xxx.Master_}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2072)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2097)
at android.app.ActivityThread.access$600(ActivityThread.java:136)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1207)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4787)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:556)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.xxx.xxx.HomeFragment.onActivityCreated(HomeFragment.java:140)
at android.support.v4.app.Fragment.performActivityCreated(Fragment.java:1508)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:958)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1115)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1097)
at android.support.v4.app.FragmentManagerImpl.dispatchActivityCreated(FragmentManager.java:1895)
at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:566)
at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1163)
at android.app.Activity.performStart(Activity.java:5018)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2045)
... 11 more

Zbar : startPreview failed in galaxy S3

I have used ZBAR library to scan bar code in my Application.
And I got this error log while opening camera on Samsung Galaxy S3 :
java.lang.RuntimeException: startPreview failed
at android.hardware.Camera.startPreview(Native Method)
at com.SGID.MainApp.ScanningFragment.engageCamera(ScanningFragment.java:184)
at com.SGID.MainApp.ScanningFragment.access$10(ScanningFragment.java:154)
at com.SGID.MainApp.ScanningFragment$4.run(ScanningFragment.java:111)
at android.os.Handler.handleCallback(Handler.java:615)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4898)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1006)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:773)
at dalvik.system.NativeStart.main(Native Method)
java.lang.RuntimeException: Unable to start activity ComponentInfo
{com.SGID.MainApp/com.SGID.MainApp.AllTabsActivity}
: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2100)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2125)
at android.app.ActivityThread.access$600(ActivityThread.java:140)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1227)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4898)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1006)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:773)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.SGID.MainApp.ParametersFragment.onCreateView(ParametersFragment.java:78)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:1478)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:927)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1086)
at android.support.v4.app.FragmentManagerImpl.dispatchActivityCreated(FragmentManager.java:1877)
at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:552)
at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1167)
at android.app.Activity.performStart(Activity.java:5216)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2073)
... 11 more
EDIT :
Getting error at this line :
CameraPreview mPreview = new CameraPreview(getActivity(), mCamera, previewCb,
autoFocusCB);
Can Anyone help me to resolve this error??
Thanks in advance..

Unable to resolve superclass of FragmentActivity

I had my environment setup on a previous machine, and I'm on a differnt MacBook. For some strange reason, I keep getting an issue with one of my classes which exend FragmentActivity. It keeps saying it can't find the FragmentActivity class, although I have the support jar in my class path, as per the image:
The detailed error message that I'm seeing is here:
10-23 23:10:16.300 26062-26062/com.testapp W/dalvikvm﹕ Unable to resolve superclass of Lcom/testapp/views/loginregistration/LoginView; (92)
10-23 23:10:16.300 26062-26062/com.testapp W/dalvikvm﹕ Link of class 'Lcom/testapp/views/loginregistration/LoginView;' failed
10-23 23:10:16.300 26062-26062/com.testapp D/AndroidRuntime﹕ Shutting down VM
10-23 23:10:16.300 26062-26062/com.testapp W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x414f8700)
10-23 23:10:16.330 26062-26062/com.testapp E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.testapp/com.testapp.views.loginregistration.LoginView}: java.lang.ClassNotFoundException: Didn't find class "com.testapp.views.loginregistration.LoginView" on path: DexPathList[[zip file "/system/framework/com.google.android.maps.jar", zip file "/data/app/com.testapp-1.apk"],nativeLibraryDirectories=[/data/app-lib/com.testapp-1, /vendor/lib, /system/lib]]
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2137)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
at android.app.ActivityThread.access$600(ActivityThread.java:141)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5103)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.ClassNotFoundException: Didn't find class "com.testapp.views.loginregistration.LoginView" on path: DexPathList[[zip file "/system/framework/com.google.android.maps.jar", zip file "/data/app/com.testapp-1.apk"],nativeLibraryDirectories=[/data/app-lib/com.testapp-1, /vendor/lib, /system/lib]]
at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:53)
at java.lang.ClassLoader.loadClass(ClassLoader.java:501)
at java.lang.ClassLoader.loadClass(ClassLoader.java:461)
at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2128)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
at android.app.ActivityThread.access$600(ActivityThread.java:141)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5103)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
Is there someting else i'm missing?

In your IDE (as shown in your screenshot), check the 'export' box next to the classpath entry that contains the missing class.
I had a similar problem with a class from the Android Support library (Unable to resolve superclass of Lcom ... PagerAdapter). It turned out a library referenced in the .classpath needed to be exported:
From:
<classpathentry
To:
<classpathentry exported="true" ...
For Eclipse users, I fixed the problem by exporting Android Private Libraries in the Java Build Path menu.

Android ComponentInfo ClassNotFoundException on some devices

Please help to understand strange application behaviour.
In almost all devices in production everything is OK, I'm using ACRA to collect crash reports. But here is what I've got from Alpha GTR device:
ComponentInfo{com.xxxxxxxxxxx /com.xxxxxxxxxxx.xxxxActivity}: java.lang.ClassNotFoundException: com.xxxxxxxxxxx.xxxxActivity
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2108)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2211)
at android.app.ActivityThread.access$600(ActivityThread.java:149)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1300)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:153)
at android.app.ActivityThread.main(ActivityThread.java:4987)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:821)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:584)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.ClassNotFoundException: com.xxxxxxxxxxx.xxxxActivity
at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:61)
at java.lang.ClassLoader.loadClass(ClassLoader.java:501)
at java.lang.ClassLoader.loadClass(ClassLoader.java:461)
at android.app.Instrumentation.newActivity(Instrumentation.java:1053)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2099)
... 11 more
java.lang.ClassNotFoundException: com.xxxxxxxxxxx.xxxxActivity
at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:61)
at java.lang.ClassLoader.loadClass(ClassLoader.java:501)
at java.lang.ClassLoader.loadClass(ClassLoader.java:461)
at android.app.Instrumentation.newActivity(Instrumentation.java:1053)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2099)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2211)
at android.app.ActivityThread.access$600(ActivityThread.java:149)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1300)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:153)
at android.app.ActivityThread.main(ActivityThread.java:4987)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:821)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:584)
at dalvik.system.NativeStart.main(Native Method)
So application failed to start with strange exception. I've already checked SO questions about it, and just adding libraries as Unable to instantiate activity... Caused by ClassNotFoundException doesn't help here.
Could it be some device-specific exception? My app uses Camera, Google Maps and GPS.

Maybe you have to check if GPS or Camera are supported by the device first?
LocationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);

Android simple app crashing when I open it [closed]

It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center.
Closed 10 years ago.
My main class:
package com.example.hi;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class SampleLogin extends Activity {
EditText txtUserName;
EditText txtPassword;
Button btnLogin;
Button btnCancel;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
txtUserName=(EditText)this.findViewById(R.id.txtUname);
txtPassword=(EditText)this.findViewById(R.id.txtPwd);
btnLogin=(Button)this.findViewById(R.id.btnLogin);
btnLogin=(Button)this.findViewById(R.id.btnLogin);
btnLogin.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
if((txtUserName.getText().toString()).equals(txtPassword.getText().toString())){
Toast.makeText(SampleLogin.this, "Login Successful",Toast.LENGTH_LONG).show();
} else{
Toast.makeText(SampleLogin.this, "Invalid Login",Toast.LENGTH_LONG).show();
}
}
});
}
}
My XML file...
<TableLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:stretchColumns="1">
<TableRow>
<TextView
android:text="#string/User_Name: "
android:id="#+id/TextView01"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
</TextView>
<EditText
android:inputType="textPassword|number"
android:text=""
android:id="#+id/txtUname"
android:layout_width="fill_parent"
android:layout_height="wrap_content">
</EditText>
</TableRow>
<TableRow>
<TextView
android:text="#string/Password: "
android:id="#+id/TextView02"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
</TextView>
<EditText
android:inputType="textPassword|number"
android:text=""
android:id="#+id/txtPwd"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
</TableRow>
<TableRow>
<Button
android:text="#string/Cancel"
android:id="#+id/btnCancel"
android:layout_width="fill_parent"
android:layout_height="wrap_content">
</Button>
<Button
android:text="#string/Login"
android:id="#+id/btnLogin"
android:layout_width="fill_parent"
android:layout_height="wrap_content">
</Button>
</TableRow>
</TableLayout>
So here is my code for some reason the application stops working when I open it, the "application () has stopped unexpectedly. please try again avd... " I have no idea why that is happening, help please!
I'm new to android, can someone tell me how do I get the catlog file?
About the Strings on the xml file, again I'm new to this, I was getting an error about "hard coded string" or something like that and it said I needed to add it to the strings file found in the res folder so I added the strings and then added the #string
CatLog File:
12-28 17:36:50.883: E/Zygote(33): setreuid() failed. errno: 2
12-28 17:37:00.573: E/Zygote(33): setreuid() failed. errno: 17
12-28 17:37:01.933: E/BatteryService(61): usbOnlinePath not found
12-28 17:37:01.933: E/BatteryService(61): batteryVoltagePath not found
12-28 17:37:01.933: E/BatteryService(61): batteryTemperaturePath not found
12-28 17:37:01.953: E/SurfaceFlinger(61): Couldn't open /sys/power/wait_for_fb_sleep or /sys/power/wait_for_fb_wake
12-28 17:37:02.173: E/SensorService(61): couldn't open device for module sensors (Invalid argument)
12-28 17:37:06.682: E/System(61): Failure starting core service
12-28 17:37:06.682: E/System(61): java.lang.SecurityException
12-28 17:37:06.682: E/System(61): at android.os.BinderProxy.transact(Native Method)
12-28 17:37:06.682: E/System(61): at android.os.ServiceManagerProxy.addService(ServiceManagerNative.java:146)
12-28 17:37:06.682: E/System(61): at android.os.ServiceManager.addService(ServiceManager.java:72)
12-28 17:37:06.682: E/System(61): at com.android.server.ServerThread.run(SystemServer.java:206)
12-28 17:37:06.712: E/EventHub(61): could not get driver version for /dev/input/mouse0, Not a typewriter
12-28 17:37:06.712: E/EventHub(61): could not get driver version for /dev/input/mice, Not a typewriter
12-28 17:37:07.122: E/SoundPool(61): error loading /system/media/audio/ui/Effect_Tick.ogg
12-28 17:37:07.122: E/SoundPool(61): error loading /system/media/audio/ui/KeypressStandard.ogg
12-28 17:37:07.122: E/SoundPool(61): error loading /system/media/audio/ui/KeypressSpacebar.ogg
12-28 17:37:07.122: E/SoundPool(61): error loading /system/media/audio/ui/KeypressDelete.ogg
12-28 17:37:07.122: E/SoundPool(61): error loading /system/media/audio/ui/KeypressReturn.ogg
12-28 17:37:07.164: E/UsbObserver(61): java.lang.NullPointerException
12-28 17:37:07.164: E/UsbObserver(61): at com.android.server.UsbObserver.init(UsbObserver.java:131)
12-28 17:37:07.164: E/UsbObserver(61): at com.android.server.UsbObserver.<init>(UsbObserver.java:65)
12-28 17:37:07.164: E/UsbObserver(61): at com.android.server.ServerThread.run(SystemServer.java:402)
12-28 17:37:07.673: E/ThrottleService(61): Could not open GPS configuration file /etc/gps.conf
12-28 17:37:08.392: E/logwrapper(135): executing /system/bin/tc failed: No such file or directory
12-28 17:37:08.392: E/logwrapper(136): executing /system/bin/tc failed: No such file or directory
12-28 17:37:08.432: E/logwrapper(138): executing /system/bin/tc failed: No such file or directory
12-28 17:37:35.198: E/AndroidRuntime(335): FATAL EXCEPTION: main
12-28 17:37:35.198: E/AndroidRuntime(335): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.hi/com.example.hi.MainActivity}: java.lang.ClassNotFoundException: com.example.hi.MainActivity in loader dalvik.system.PathClassLoader[/data/app/com.example.hi-1.apk]
12-28 17:37:35.198: E/AndroidRuntime(335): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1569)
12-28 17:37:35.198: E/AndroidRuntime(335): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
12-28 17:37:35.198: E/AndroidRuntime(335): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
12-28 17:37:35.198: E/AndroidRuntime(335): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
12-28 17:37:35.198: E/AndroidRuntime(335): at android.os.Handler.dispatchMessage(Handler.java:99)
12-28 17:37:35.198: E/AndroidRuntime(335): at android.os.Looper.loop(Looper.java:123)
12-28 17:37:35.198: E/AndroidRuntime(335): at android.app.ActivityThread.main(ActivityThread.java:3683)
12-28 17:37:35.198: E/AndroidRuntime(335): at java.lang.reflect.Method.invokeNative(Native Method)
12-28 17:37:35.198: E/AndroidRuntime(335): at java.lang.reflect.Method.invoke(Method.java:507)
12-28 17:37:35.198: E/AndroidRuntime(335): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
12-28 17:37:35.198: E/AndroidRuntime(335): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
12-28 17:37:35.198: E/AndroidRuntime(335): at dalvik.system.NativeStart.main(Native Method)
12-28 17:37:35.198: E/AndroidRuntime(335): Caused by: java.lang.ClassNotFoundException: com.example.hi.MainActivity in loader dalvik.system.PathClassLoader[/data/app/com.example.hi-1.apk]
12-28 17:37:35.198: E/AndroidRuntime(335): at dalvik.system.PathClassLoader.findClass(PathClassLoader.java:240)
12-28 17:37:35.198: E/AndroidRuntime(335): at java.lang.ClassLoader.loadClass(ClassLoader.java:551)
12-28 17:37:35.198: E/AndroidRuntime(335): at java.lang.ClassLoader.loadClass(ClassLoader.java:511)
12-28 17:37:35.198: E/AndroidRuntime(335): at android.app.Instrumentation.newActivity(Instrumentation.java:1021)
12-28 17:37:35.198: E/AndroidRuntime(335): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1561)
12-28 17:37:35.198: E/AndroidRuntime(335): ... 11 more
12-28 17:38:05.517: E/AndroidRuntime(344): FATAL EXCEPTION: main
12-28 17:38:05.517: E/AndroidRuntime(344): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.hi/com.example.hi.MainActivity}: java.lang.ClassNotFoundException: com.example.hi.MainActivity in loader dalvik.system.PathClassLoader[/data/app/com.example.hi-1.apk]
12-28 17:38:05.517: E/AndroidRuntime(344): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1569)
12-28 17:38:05.517: E/AndroidRuntime(344): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
12-28 17:38:05.517: E/AndroidRuntime(344): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
12-28 17:38:05.517: E/AndroidRuntime(344): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
12-28 17:38:05.517: E/AndroidRuntime(344): at android.os.Handler.dispatchMessage(Handler.java:99)
12-28 17:38:05.517: E/AndroidRuntime(344): at android.os.Looper.loop(Looper.java:123)
12-28 17:38:05.517: E/AndroidRuntime(344): at android.app.ActivityThread.main(ActivityThread.java:3683)
12-28 17:38:05.517: E/AndroidRuntime(344): at java.lang.reflect.Method.invokeNative(Native Method)
12-28 17:38:05.517: E/AndroidRuntime(344): at java.lang.reflect.Method.invoke(Method.java:507)
12-28 17:38:05.517: E/AndroidRuntime(344): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
12-28 17:38:05.517: E/AndroidRuntime(344): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
12-28 17:38:05.517: E/AndroidRuntime(344): at dalvik.system.NativeStart.main(Native Method)
12-28 17:38:05.517: E/AndroidRuntime(344): Caused by: java.lang.ClassNotFoundException: com.example.hi.MainActivity in loader dalvik.system.PathClassLoader[/data/app/com.example.hi-1.apk]
12-28 17:38:05.517: E/AndroidRuntime(344): at dalvik.system.PathClassLoader.findClass(PathClassLoader.java:240)
12-28 17:38:05.517: E/AndroidRuntime(344): at java.lang.ClassLoader.loadClass(ClassLoader.java:551)
12-28 17:38:05.517: E/AndroidRuntime(344): at java.lang.ClassLoader.loadClass(ClassLoader.java:511)
12-28 17:38:05.517: E/AndroidRuntime(344): at android.app.Instrumentation.newActivity(Instrumentation.java:1021)
12-28 17:38:05.517: E/AndroidRuntime(344): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1561)
12-28 17:38:05.517: E/AndroidRuntime(344): ... 11 more
It doesn't crash anymore but I can't type anything!! I changed something on the xml file about typing because it was giving me a problem
android:inputType="textPassword|number"
I think it was this but when I try to type something it does nothing!
Is this supposed to work?
<EditText
android:inputType="textPassword|number"
android:text=""
android:id="#+id/txtPwd"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
<EditText
android:inputType="textPassword|number"
android:text=""
android:id="#+id/txtUname"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />

From your LogCat:
Caused by: java.lang.ClassNotFoundException: com.example.hi.MainActivity in loader dalvik.system.PathClassLoader[/data/app/com.example.hi-1.apk]
This means that you probably changed your class name to SampleLogin from MainActivity but forgot to update your manifest.
Update the manifest to look like this:
<activity
android:name=".SampleLogin"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
(You will also need to address android:text="#string/User_Name: " and android:text="#string/Password: " as I mentioned in the comments before you can compile your app again.)

You should see the LogCat to know what is the error exactly.
The only thing I can spot in your code is that you are initilizing the btnLogin twice and missing the initialization of btnCancel. This would not be the source of the error unless you are using btnCancel object somewhere.
btnLogin=(Button)this.findViewById(R.id.btnLogin);
btnLogin=(Button)this.findViewById(R.id.btnLogin);
If you can post the error from LogCat, it will be easier to help.
Edit
In your layout XML file you have something looks odd
android:text="#string/Password: "
android:id="#+id/TextView01"
There are not appropriate name for resources it should be all small letters with only underscore as word separator if needed.