Android Development- Intents

Question

I have recently started Android development on API version 16 (4.1). According to the tutorials that are available on developer.android.com I started to develop the app which taught me the use of Intents. The problem is that as soon as my app is loading on the Emulator it shows the error that the app had to shut down. I am giving my xml code. Can someone please tell me where I am going wrong? Thanks.

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent" 
android:orientation="horizontal">


<EditText
    android:id="@+id/et1"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:hint="Edit text"
    android:layout_weight="1"
    tools:ignore="HardcodedText" />

<Button
    android:id="@+id/b1"
    android:layout_width="wrap_content"
    android:layout_height="40dp"
    android:text="Press"
    android:onClick="sendMessage"
    tools:ignore="HardcodedText" />

</LinearLayout>

The logcat is given below.

09-26 19:35:03.880: E/Trace(615): error opening trace file: No such file or directory     (2)
09-26 19:35:04.430: D/AndroidRuntime(615): Shutting down VM
09-26 19:35:04.430: W/dalvikvm(615): threadid=1: thread exiting with uncaught exception  (group=0x40a13300)
09-26 19:35:04.471: E/AndroidRuntime(615): FATAL EXCEPTION: main
09-26 19:35:04.471: E/AndroidRuntime(615): java.lang.RuntimeException: Unable to     instantiate activity ComponentInfo{com.learn.training1/com.learn.training1.Training1}:     java.lang.NullPointerException
 09-26 19:35:04.471: E/AndroidRuntime(615):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1983)
09-26 19:35:04.471: E/AndroidRuntime(615):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
09-26 19:35:04.471: E/AndroidRuntime(615):  at android.app.ActivityThread.access$600(ActivityThread.java:130)
09-26 19:35:04.471: E/AndroidRuntime(615):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
09-26 19:35:04.471: E/AndroidRuntime(615):  at android.os.Handler.dispatchMessage(Handler.java:99)
09-26 19:35:04.471: E/AndroidRuntime(615):  at android.os.Looper.loop(Looper.java:137)
09-26 19:35:04.471: E/AndroidRuntime(615):  at android.app.ActivityThread.main(ActivityThread.java:4745)
09-26 19:35:04.471: E/AndroidRuntime(615):  at java.lang.reflect.Method.invokeNative(Native Method)
09-26 19:35:04.471: E/AndroidRuntime(615):  at java.lang.reflect.Method.invoke(Method.java:511)
09-26 19:35:04.471: E/AndroidRuntime(615):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
09-26 19:35:04.471: E/AndroidRuntime(615):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
09-26 19:35:04.471: E/AndroidRuntime(615):  at dalvik.system.NativeStart.main(Native Method)
09-26 19:35:04.471: E/AndroidRuntime(615): Caused by: java.lang.NullPointerException
09-26 19:35:04.471: E/AndroidRuntime(615):  at android.app.Activity.findViewById(Activity.java:1825)
09-26 19:35:04.471: E/AndroidRuntime(615):  at com.learn.training1.Training1.<init>(Training1.java:15)
09-26 19:35:04.471: E/AndroidRuntime(615):  at java.lang.Class.newInstanceImpl(Native Method)
09-26 19:35:04.471: E/AndroidRuntime(615):  at java.lang.Class.newInstance(Class.java:1319)
09-26 19:35:04.471: E/AndroidRuntime(615):  at android.app.Instrumentation.newActivity(Instrumentation.java:1053)
09-26 19:35:04.471: E/AndroidRuntime(615):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1974)
09-26 19:35:04.471: E/AndroidRuntime(615):  ... 11 more
09-26 19:35:32.352: I/Process(615): Sending signal. PID: 615 SIG: 9
09-26 19:39:22.460: E/Trace(664): error opening trace file: No such file or directory (2)
09-26 19:39:22.820: D/AndroidRuntime(664): Shutting down VM
09-26 19:39:22.820: W/dalvikvm(664): threadid=1: thread exiting with uncaught exception (group=0x40a13300)
09-26 19:39:22.846: E/AndroidRuntime(664): FATAL EXCEPTION: main
09-26 19:39:22.846: E/AndroidRuntime(664): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.learn.training1/com.learn.training1.Training1}: java.lang.NullPointerException
 09-26 19:39:22.846: E/AndroidRuntime(664):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1983)
09-26 19:39:22.846: E/AndroidRuntime(664):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
09-26 19:39:22.846: E/AndroidRuntime(664):  at android.app.ActivityThread.access$600(ActivityThread.java:130)
09-26 19:39:22.846: E/AndroidRuntime(664):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
09-26 19:39:22.846: E/AndroidRuntime(664):  at android.os.Handler.dispatchMessage(Handler.java:99)
09-26 19:39:22.846: E/AndroidRuntime(664):  at android.os.Looper.loop(Looper.java:137)
09-26 19:39:22.846: E/AndroidRuntime(664):  at android.app.ActivityThread.main(ActivityThread.java:4745)
09-26 19:39:22.846: E/AndroidRuntime(664):  at java.lang.reflect.Method.invokeNative(Native Method)
09-26 19:39:22.846: E/AndroidRuntime(664):  at java.lang.reflect.Method.invoke(Method.java:511)
09-26 19:39:22.846: E/AndroidRuntime(664):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
09-26 19:39:22.846: E/AndroidRuntime(664):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
09-26 19:39:22.846: E/AndroidRuntime(664):  at dalvik.system.NativeStart.main(Native Method)
09-26 19:39:22.846: E/AndroidRuntime(664): Caused by: java.lang.NullPointerException
09-26 19:39:22.846: E/AndroidRuntime(664):  at android.app.Activity.findViewById(Activity.java:1825)
09-26 19:39:22.846: E/AndroidRuntime(664):  at com.learn.training1.Training1.<init>(Training1.java:15)
09-26 19:39:22.846: E/AndroidRuntime(664):  at java.lang.Class.newInstanceImpl(Native Method)
09-26 19:39:22.846: E/AndroidRuntime(664):  at java.lang.Class.newInstance(Class.java:1319)
09-26 19:39:22.846: E/AndroidRuntime(664):  at android.app.Instrumentation.newActivity(Instrumentation.java:1053)
09-26 19:39:22.846: E/AndroidRuntime(664):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1974)
09-26 19:39:22.846: E/AndroidRuntime(664):  ... 11 more
09-26 19:40:29.130: E/Trace(712): error opening trace file: No such file or directory (2)
09-26 19:40:29.431: D/dalvikvm(712): newInstance failed: Lcom/learn/training1/Training1; not accessible to Landroid/app/Instrumentation;
09-26 19:40:29.431: D/AndroidRuntime(712): Shutting down VM
09-26 19:40:29.431: W/dalvikvm(712): threadid=1: thread exiting with uncaught exception (group=0x40a13300)
09-26 19:40:29.461: E/AndroidRuntime(712): FATAL EXCEPTION: main
09-26 19:40:29.461: E/AndroidRuntime(712): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.learn.training1/com.learn.training1.Training1}: java.lang.IllegalAccessException: access to class not allowed
09-26 19:40:29.461: E/AndroidRuntime(712):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1983)
09-26 19:40:29.461: E/AndroidRuntime(712):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
09-26 19:40:29.461: E/AndroidRuntime(712):  at android.app.ActivityThread.access$600(ActivityThread.java:130)
09-26 19:40:29.461: E/AndroidRuntime(712):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
09-26 19:40:29.461: E/AndroidRuntime(712):  at android.os.Handler.dispatchMessage(Handler.java:99)
09-26 19:40:29.461: E/AndroidRuntime(712):  at android.os.Looper.loop(Looper.java:137)
09-26 19:40:29.461: E/AndroidRuntime(712):  at android.app.ActivityThread.main(ActivityThread.java:4745)
09-26 19:40:29.461: E/AndroidRuntime(712):  at java.lang.reflect.Method.invokeNative(Native Method)
09-26 19:40:29.461: E/AndroidRuntime(712):  at java.lang.reflect.Method.invoke(Method.java:511)
09-26 19:40:29.461: E/AndroidRuntime(712):  at  com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
09-26 19:40:29.461: E/AndroidRuntime(712):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
09-26 19:40:29.461: E/AndroidRuntime(712):  at dalvik.system.NativeStart.main(Native Method)
09-26 19:40:29.461: E/AndroidRuntime(712): Caused by: java.lang.IllegalAccessException: access to class not allowed
09-26 19:40:29.461: E/AndroidRuntime(712):  at java.lang.Class.newInstanceImpl(Native Method)
09-26 19:40:29.461: E/AndroidRuntime(712):  at java.lang.Class.newInstance(Class.java:1319)
09-26 19:40:29.461: E/AndroidRuntime(712):  at android.app.Instrumentation.newActivity(Instrumentation.java:1053)
09-26 19:40:29.461: E/AndroidRuntime(712):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1974)
09-26 19:40:29.461: E/AndroidRuntime(712):  ... 11 more
09-26 19:43:52.020: E/Trace(760): error opening trace file: No such file or directory (2)
09-26 19:43:52.110: D/dalvikvm(760): newInstance failed: Lcom/learn/training1/Training1; not accessible to Landroid/app/Instrumentation;
09-26 19:43:52.110: D/AndroidRuntime(760): Shutting down VM
09-26 19:43:52.110: W/dalvikvm(760): threadid=1: thread exiting with uncaught exception (group=0x40a13300)
09-26 19:43:52.190: E/AndroidRuntime(760): FATAL EXCEPTION: main
09-26 19:43:52.190: E/AndroidRuntime(760): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.learn.training1/com.learn.training1.Training1}: java.lang.IllegalAccessException: access to class not allowed
09-26 19:43:52.190: E/AndroidRuntime(760):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1983)
09-26 19:43:52.190: E/AndroidRuntime(760):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
09-26 19:43:52.190: E/AndroidRuntime(760):  at android.app.ActivityThread.access$600(ActivityThread.java:130)
09-26 19:43:52.190: E/AndroidRuntime(760):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
09-26 19:43:52.190: E/AndroidRuntime(760):  at android.os.Handler.dispatchMessage(Handler.java:99)
09-26 19:43:52.190: E/AndroidRuntime(760):  at android.os.Looper.loop(Looper.java:137)
09-26 19:43:52.190: E/AndroidRuntime(760):  at android.app.ActivityThread.main(ActivityThread.java:4745)
09-26 19:43:52.190: E/AndroidRuntime(760):  at java.lang.reflect.Method.invokeNative(Native Method)
 09-26 19:43:52.190: E/AndroidRuntime(760):     at java.lang.reflect.Method.invoke(Method.java:511)
09-26 19:43:52.190: E/AndroidRuntime(760):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
09-26 19:43:52.190: E/AndroidRuntime(760):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
09-26 19:43:52.190: E/AndroidRuntime(760):  at dalvik.system.NativeStart.main(Native Method)
09-26 19:43:52.190: E/AndroidRuntime(760): Caused by: java.lang.IllegalAccessException: access to class not allowed
09-26 19:43:52.190: E/AndroidRuntime(760):  at java.lang.Class.newInstanceImpl(Native Method)
09-26 19:43:52.190: E/AndroidRuntime(760):  at java.lang.Class.newInstance(Class.java:1319)
09-26 19:43:52.190: E/AndroidRuntime(760):  at android.app.Instrumentation.newActivity(Instrumentation.java:1053)
09-26 19:43:52.190: E/AndroidRuntime(760):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1974)
09-26 19:43:52.190: E/AndroidRuntime(760):  ... 11 more
09-26 19:47:20.550: I/Process(810): Sending signal. PID: 810 SIG: 9

Answer 1

Looks like your activity isn't properly declared (maybe you didn't make it public ?). You should have a file called Training1.java and in this file you should have something like

public class Training1 extends Activity {
    ...your activity code here...
}

See https://groups.google.com/forum/?fromgroups=#!topic/android-developers/0Gw5WHc1J6g

EDIT: Add note

Note: Also, you shouldn't have any constructors. The Android framework takes care of that for you.