My android app is giving a long error and is not starting

Question

I am getting an error while trying to run my app in my emulator

I am following a tutorial that shows you how to make an app like WhatsApp but I am having some trouble. Whenever I try to run the app in my emulator I get this really long error that I can't seem to solve. The only thing I changed that might've been of importance was the file name. It was MainActivity.jk or tk I forgot. But I changed it to MainActivity.Java. But this is the error I keep getting.

04-19 13:30:10.485 3614-3614/? E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.chatster, PID: 3614 java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.chatster/com.example.chatster.MainActivity}: java.lang.ClassNotFoundException: Didn't find class "com.example.chatster.MainActivity" on path: DexPathList[[zip file "/data/app/com.example.chatster-1.apk"],nativeLibraryDirectories=[/data/app-lib/com.example.chatster-1, /vendor/lib, /system/lib]] at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2121) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245) at android.app.ActivityThread.access$800(ActivityThread.java:135) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:136) at android.app.ActivityThread.main(ActivityThread.java:5017) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:515) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) at dalvik.system.NativeStart.main(Native Method) Caused by: java.lang.ClassNotFoundException: Didn't find class "com.example.chatster.MainActivity" on path: DexPathList[[zip file "/data/app/com.example.chatster-1.apk"],nativeLibraryDirectories=[/data/app-lib/com.example.chatster-1, /vendor/lib, /system/lib]] at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56) at java.lang.ClassLoader.loadClass(ClassLoader.java:497) at java.lang.ClassLoader.loadClass(ClassLoader.java:457) at android.app.Instrumentation.newActivity(Instrumentation.java:1061) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2112) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245) at android.app.ActivityThread.access$800(ActivityThread.java:135) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:136) at android.app.ActivityThread.main(ActivityThread.java:5017) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:515) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) at dalvik.system.NativeStart.main(Native Method)

MainActivity.Java

package com.example.chatster;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;

import java.util.Objects;

public class MainActivity extends AppCompatActivity {

protected Bundle savedInstanceState;

@Override
protected void onCreate(Bundle savedInstanceState)
{
    this.savedInstanceState = savedInstanceState;

    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    Toolbar mToolBar = (Toolbar) findViewById(R.id.Main_page_toolbar);
    setSupportActionBar(mToolBar);
    Objects.requireNonNull(getSupportActionBar()).setTitle("Chatster");
}

}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:tools="http://schemas.android.com/tools"
      package="com.example.chatster">

<application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme" tools:ignore="AllowBackup,GoogleAppIndexingWarning">
    <activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN"/>
            <category android:name="android.intent.category.LAUNCHER"/>
        </intent-filter>
    </activity>
</application>

</manifest>

Possible duplicate of [java.lang.RuntimeException: Unable to instantiate activity ComponentInfo](https://stackoverflow.com/questions/4688277/java-lang-runtimeexception-unable-to-instantiate-activity-componentinfo) — user1506104, Apr 19 '19 at 19:19
Add Screenshot of your project structure, so that we can see in which package does your MainActivity exist. — TheAnkush, Apr 19 '19 at 19:41
I can't because there is something wrong with my computer but it's under the android tab. app\java\chatster\com.example.chatster\MainActivity.Java — , Apr 19 '19 at 20:29
did you try putting in app/src/main/java/com/example/chatster/MainActivity.java? — user1506104, Apr 20 '19 at 06:40

ismail alaoui · Answer 1 · 2019-04-19T19:13:04.563

0

this seems to be problem in your case.: The relative path of your activity in manifest is not correct or your didn't declare your activity in your androidManifest

<activity android:name="com.example.chatster.MainActivity"

Please try to remvoe this line from your onCreate()

this.savedInstanceState = savedInstanceState ;

After you did this please clean and rebuild your project and restart your android studio

Please check this link for more information and hope you will resolve the problem

edited Apr 19 '19 at 19:13

answered Apr 19 '19 at 18:07

ismail alaoui

5,748
2
21
38

Sorry I forgot to put my android manifest file in there take a look at it now – Apr 19 '19 at 18:12
try to declare your activity as i wrote above with the package – ismail alaoui Apr 19 '19 at 18:13
I added that line. Then I cleaned the project, then I rebuilt it and it still doesn't work – Apr 19 '19 at 18:16
Yes. Still the same one – Apr 19 '19 at 18:54
Clean rebuild amd restart your android studio ! – ismail alaoui Apr 19 '19 at 19:06
Thanks but that didn't help – Apr 19 '19 at 19:31

score 0 · Answer 2 · answered Apr 19 '19 at 19:19

0

Disable instant run in Android Studio.

Go to File -> Settings/Preferences (Mac) -> Build Execution and Deployment -> Uncheck Instant Run

Then Clean and rebuild the project.

answered Apr 19 '19 at 19:19

TheAnkush

885
7
10

Is your multidex enabled to true in gradle file? – TheAnkush Apr 19 '19 at 19:32
there is no multidex in my gradle files – Apr 19 '19 at 19:35
Ok, did you try Invalidate cache and restart from File option in Android Studio? If not could you check. – TheAnkush Apr 19 '19 at 19:39
Yes I did try that – Apr 19 '19 at 20:28

My android app is giving a long error and is not starting

2 Answers2