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>

2 Answers

0
ismail alaoui On

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

0
TheAnkush On

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.

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