CODEWITHSUNDEEP
javaandroidmanifestruntimeexception
Adam
Adam

Reputation: 153

java.lang.RuntimeException: Unable to instantiate activit

I'm trying to write an Android app that logs when you click a button it will put text into the console, however I am getting an error when I complie it and run it on my Galaxy S7 edge running 7.0 API version 24.

I've read that I need to add something into the manifest file however I am not sure what I need to add.

FATAL EXCEPTION: main Process: me.adamstephenson.test.test1, PID: 16405 java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{me.adamstephenson.test.test1/me.adamstephenson.test.test1.MainActivity}: java.lang.ClassCastException: me.adamstephenson.test.test1.MainActivity cannot be cast to android.app.Activity

package me.adamstephenson.test.test1;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;

public class MainActivity {
    public class MyActivity extends Activity {
        protected void onCreate(Bundle icicle) {
            super.onCreate(icicle);

            setContentView(R.layout.activity_main);

            final Button button = (Button) findViewById(R.id.RequestKey);
            button.setOnClickListener(new View.OnClickListener() {
                public void onClick(View v) {
                    Log.d("RequestKey", "Clicked");
                }
            });
        }
    }
}

Source

Here is the layout

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="me.adamstephenson.test.test1.MainActivity">

<Button
    android:id="@+id/RequestKey"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Button"
    tools:layout_editor_absoluteX="196dp"
    tools:layout_editor_absoluteY="129dp" />
</android.support.constraint.ConstraintLayout>

Finally here is the manifest file

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="me.adamstephenson.test.test1">

<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">
    <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>

Upvotes: 0

Views: 4639

Answers (2)

ACAkgul
ACAkgul

Reputation: 188

Because your activity class is created as a inner class and static class. I don't have any idea why did you choose this way while you can use it this proper way:

public class MyActivity extends Activity {

    protected void onCreate(Bundle icicle) {
        super.onCreate(icicle);

        setContentView(R.layout.activity_main);

        final Button button = (Button) findViewById(R.id.RequestKey);
        button.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                Log.d("RequestKey", "Clicked");
            }
        });
    }
    .
    .
    .
     // other methods or inner class can exist here
   }

Upvotes: 1

Nika Kurdadze
Nika Kurdadze

Reputation: 2512

You are referring to the wrong class in your manifest. MyActivity is the Activity, not MainActivity. Change your manifest to the following :

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="me.adamstephenson.test.test1">

    <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">
        <activity android:name=".MainActivity$MyActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

And

You should make your inner activity static as well :

public class MainActivity {
    public static class MyActivity extends Activity {
        ...
    }
}

Upvotes: 1

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