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Android

Posted by Rachit Singh
Rachit Singh
Courses Plus Student 197 Points

CANT RUN APP on android emulator

i cant run my app which i created in android studio and when i run the app it says unfortunately "app name" has stopped working plz help me plz

jungkeekim
jungkeekim
Courses Plus Student 2,333 Points

While you were working, did you change app name or package name after making a new project.

The best solution is...

  1. make a new project.
  2. copy the code(just algorithm, no package name, no class name) from the old project.
  3. paste the code into the new project.

If this is not the right answer, please post your logcat message.

6 Answers

Steve Hunter
Steve Hunter
57,712 Points
Steve Hunter
Steve Hunter
57,712 Points

Hi Rachit,

If you can copy your Logcat contents into a post, we can view the precise error that is halting your code execution.

Also, try a Clean and then a Rebuild from inside the Build menu. Sometimes trying File | Invalidate cashes & restart can help too. But, starting at Logcat is best; that's where the error is likely to be highlighted.

Steve.

Rachit Singh
Rachit Singh
Courses Plus Student 197 Points

i am a beginner to this so can u plz tell me in easy language what is logcat

Rachit Singh
Rachit Singh
Courses Plus Student 197 Points

do you want event log

Rachit Singh
Rachit Singh
Courses Plus Student 197 Points

04-23 21:45:05.154 2134-2134/com.example.android.funfacts E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.android.funfacts, PID: 2134 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.android.funfacts/com.example.android.funfacts.FunfactsActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) at android.app.ActivityThread.-wrap11(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5417) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference at com.example.android.funfacts.FunfactsActivity.onCreate(FunfactsActivity.java:31) at android.app.Activity.performCreate(Activity.java:6237) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)  at android.app.ActivityThread.-wrap11(ActivityThread.java)  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)  at android.os.Handler.dispatchMessage(Handler.java:102)  at android.os.Looper.loop(Looper.java:148)  at android.app.ActivityThread.main(ActivityThread.java:5417)  at java.lang.reflect.Method.invoke(Native Method)  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

Rachit Singh
Rachit Singh
Courses Plus Student 197 Points

04-23 21:45:05.154 2134-2134/com.example.android.funfacts E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.android.funfacts, PID: 2134 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.android.funfacts/com.example.android.funfacts.FunfactsActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) at android.app.ActivityThread.-wrap11(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5417) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference at com.example.android.funfacts.FunfactsActivity.onCreate(FunfactsActivity.java:31) at android.app.Activity.performCreate(Activity.java:6237) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) at android.app.ActivityThread.-wrap11(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5417) at java.lang.reflect.Method.invoke(Native Method)

Rachit Singh
Rachit Singh
Courses Plus Student 197 Points

till native method was the errror other posts r wrong

Rachit Singh
PLUS
Rachit Singh
Courses Plus Student 197 Points
Rachit Singh
Rachit Singh
Courses Plus Student 197 Points

i am a beginner to this so can u plz tell me in easy language what is logcat

Steve Hunter
Steve Hunter
57,712 Points

OK cool. The log is probably showing up across the bottom of Android Studio. It'll show lots of messages. Copy the red ones into here.

I'll grab a screenshots later. I'm out at the moment.

Rachit Singh
PLUS
Rachit Singh
Courses Plus Student 197 Points
Rachit Singh
Rachit Singh
Courses Plus Student 197 Points

04-23 21:45:05.154 2134-2134/com.example.android.funfacts E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.android.funfacts, PID: 2134 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.android.funfacts/com.example.android.funfacts.FunfactsActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) at android.app.ActivityThread.-wrap11(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5417) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference at com.example.android.funfacts.FunfactsActivity.onCreate(FunfactsActivity.java:31) at android.app.Activity.performCreate(Activity.java:6237) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)  at android.app.ActivityThread.-wrap11(ActivityThread.java)  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)  at android.os.Handler.dispatchMessage(Handler.java:102)  at android.os.Looper.loop(Looper.java:148)  at android.app.ActivityThread.main(ActivityThread.java:5417)  at java.lang.reflect.Method.invoke(Native Method)  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)  04-23 21:45:05.154 2134-2134/com.example.android.funfacts E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.android.funfacts, PID: 2134 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.android.funfacts/com.example.android.funfacts.FunfactsActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) at android.app.ActivityThread.-wrap11(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5417) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference at com.example.android.funfacts.FunfactsActivity.onCreate(FunfactsActivity.java:31) at android.app.Activity.performCreate(Activity.java:6237) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)  at android.app.ActivityThread.-wrap11(ActivityThread.java)  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)  at android.os.Handler.dispatchMessage(Handler.java:102)  at android.os.Looper.loop(Looper.java:148)  at android.app.ActivityThread.main(ActivityThread.java:5417)  at java.lang.reflect.Method.invoke(Native Method)  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)  04-23 21:45:05.154 2134-2134/com.example.android.funfacts E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.android.funfacts, PID: 2134 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.android.funfacts/com.example.android.funfacts.FunfactsActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) at android.app.ActivityThread.-wrap11(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5417) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference at com.example.android.funfacts.FunfactsActivity.onCreate(FunfactsActivity.java:31) at android.app.Activity.performCreate(Activity.java:6237) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)  at android.app.ActivityThread.-wrap11(ActivityThread.java)  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)  at android.os.Handler.dispatchMessage(Handler.java:102)  at android.os.Looper.loop(Looper.java:148)  at android.app.ActivityThread.main(ActivityThread.java:5417)  at java.lang.reflect.Method.invoke(Native Method)  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)  04-23 21:45:05.154 2134-2134/com.example.android.funfacts E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.android.funfacts, PID: 2134 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.android.funfacts/com.example.android.funfacts.FunfactsActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) at android.app.ActivityThread.-wrap11(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5417) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference at com.example.android.funfacts.FunfactsActivity.onCreate(FunfactsActivity.java:31) at android.app.Activity.performCreate(Activity.java:6237) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)  at android.app.ActivityThread.-wrap11(ActivityThread.java)  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)  at android.os.Handler.dispatchMessage(Handler.java:102)  at android.os.Looper.loop(Looper.java:148)  at android.app.ActivityThread.main(ActivityThread.java:5417)  at java.lang.reflect.Method.invoke(Native Method)  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)  04-23 21:45:05.154 2134-2134/com.example.android.funfacts E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.android.funfacts, PID: 2134 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.android.funfacts/com.example.android.funfacts.FunfactsActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) at android.app.ActivityThread.-wrap11(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5417) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference at com.example.android.funfacts.FunfactsActivity.onCreate(FunfactsActivity.java:31) at android.app.Activity.performCreate(Activity.java:6237) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)  at android.app.ActivityThread.-wrap11(ActivityThread.java)  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)  at android.os.Handler.dispatchMessage(Handler.java:102)  at android.os.Looper.loop(Looper.java:148)  at android.app.ActivityThread.main(ActivityThread.java:5417)  at java.lang.reflect.Method.invoke(Native Method)  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

jungkeekim
PLUS
jungkeekim
Courses Plus Student 2,333 Points
jungkeekim
jungkeekim
Courses Plus Student 2,333 Points

can you post your MainActiviti code?

Rachit Singh
Rachit Singh
Courses Plus Student 197 Points

<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="wrap_content" android:paddingBottom="@dimen/activity_vertical_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" tools:context="com.example.android.funfacts.FunfactsActivity" android:background="#51b46d">

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Ant stretch when they wake up in the morning"
    android:id="@+id/textView"
    android:layout_marginTop="146dp"
    android:textSize="24sp"
    android:layout_alignParentStart="true"
    android:singleLine="false"
    android:textColor="@android:color/black" />

<Button
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="TAP ME for more Fun Facts"
    android:id="@+id/button"
    android:layout_alignParentBottom="true"
    android:layout_centerHorizontal="true"
    android:layout_marginBottom="78dp"
    android:background="@android:color/white" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:text="Did you know"
    android:id="@+id/textView2"
    android:layout_alignParentTop="true"
    android:layout_alignParentStart="true"/>

</RelativeLayout>

Steve Hunter
Steve Hunter
57,712 Points
Steve Hunter
Steve Hunter
57,712 Points

We need your FunFactsActivity.java code - you have something pointing at nothing ... a NullPointerException. This is happening at line 31. I'm guessing this is an ActionBar issue, but I'll wait for the code!

Can you post that file's code and let me know which line is 31 (I'm lazy & hate counting lines!!) :wink:

Steve.

Steve Hunter
Steve Hunter
57,712 Points

Looking at the trace it's called FunfactsActivity.java; sorry!

Rachit Singh
Rachit Singh
Courses Plus Student 197 Points 
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class FunfactsActivity extends AppCompatActivity {
//  Declare our view variable
    private TextView mFactTextView;
    private Button mShowFactButton;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_funfacts);

        // Assing the Views from the layout file to the corresponding vaariable
        mFactTextView=(TextView) findViewById(R.id.factTextView);
        mShowFactButton= (Button) findViewById(R.id.showFactButton);
        View.OnClickListener listener = new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // The button was clicked, so update the fact TextView with a new fact
                String fact="Ostriches can run faster than horses.";
                mFactTextView.setText(fact);

            }
        };
        mShowFactButton.setOnClickListener(listener);
    }
}
Rachit Singh
Rachit Singh
Courses Plus Student 197 Points

this line was in red colour in event log

NoClassDefFoundError: Could not initialize class com.sun.jna.Native

Rachit Singh
Rachit Singh
Courses Plus Student 197 Points

Gradle sync failed: Unable to start the daemon process. This problem might be caused by incorrect configuration of the daemon. For example, an unrecognized jvm option is used. Please refer to the user guide chapter on the daemon at https://docs.gradle.org/2.8/userguide/gradle_daemon.html Please read the following process output to find out more: ----------------------- Error occurred during initialization of VM Could not reserve enough space for object heap Error: Could not create the Java Virtual Machine. Error: A fatal exception has occurred. Program will exit. Consult IDE log for more details (Help | Show Log) 7:02:07 PM Gradle sync started 7:02:08 PM Gradle sync failed: Unable to start the daemon process. This problem might be caused by incorrect configuration of the daemon. For example, an unrecognized jvm option is used. Please refer to the user guide chapter on the daemon at https://docs.gradle.org/2.8/userguide/gradle_daemon.html Please read the following process output to find out more: ----------------------- Error occurred during initialization of VM Could not reserve enough space for object heap Error: Could not create the Java Virtual Machine. Error: A fatal exception has occurred. Program will exit. Consult IDE log for more details (Help | Show Log) 7:03:11 PM NullPointerException: null 7:03:13 PM NullPointerException: null 7:03:19 PM NullPointerException: null 7:03:21 PM NullPointerException: null

Nicholas Gorman
Nicholas Gorman
1,718 Points
Nicholas Gorman
Nicholas Gorman
1,718 Points

Did you ever get this answered? I'm assuming the f in facts not being capitalized was it