Unable to instantiate activity

Question

i create another class Voice and then use abstract class voice, got error

update1

public class MainActivity extends ActionBarActivity {
    Voice v;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        v.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

    }

05-27 11:42:30.432  17775-17775/com.example.mtartin.myapplication1 E/AndroidRuntime﹕ FATAL EXCEPTION: main
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.mtartin.myapplication1/com.example.mtartin.myapplication1.MainActivity}: java.lang.NullPointerException
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2110)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2135)
            at android.app.ActivityThread.access$700(ActivityThread.java:140)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1237)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:4921)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1038)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:805)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.NullPointerException
            at com.example.mtartin.myapplication1.MainActivity.onCreate(MainActivity.java:24)
            at android.app.Activity.performCreate(Activity.java:5206)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2074)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2135)
            at android.app.ActivityThread.access$700(ActivityThread.java:140)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1237)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:4921)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1038)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:805)
            at dalvik.system.NativeStart.main(Native Method)

i follow this https://www.youtube.com/watch?v=XGvUCx9FBS4

it can make project successful when i run apps, in debug in samsung mobile, it has error,

only this no problem public class MainActivity extends ActionBarActivity

but it request to use abstract class otherwise failed to make project

05-27 10:14:41.338  12876-12876/com.example.mtartin.myapplication1 E/AndroidRuntime﹕ FATAL EXCEPTION: main
    java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.mtartin.myapplication1/com.example.mtartin.myapplication1.MainActivity}: java.lang.InstantiationException: can't instantiate class com.example.mtartin.myapplication1.MainActivity
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2034)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2135)
            at android.app.ActivityThread.access$700(ActivityThread.java:140)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1237)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:4921)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1038)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:805)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.InstantiationException: can't instantiate class com.example.mtartin.myapplication1.MainActivity
            at java.lang.Class.newInstanceImpl(Native Method)
            at java.lang.Class.newInstance(Class.java:1319)
            at android.app.Instrumentation.newActivity(Instrumentation.java:1068)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2025)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2135)
            at android.app.ActivityThread.access$700(ActivityThread.java:140)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1237)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:4921)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1038)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:805)
            at dalvik.system.NativeStart.main(Native Method)

package com.example.mtartin.myapplication1;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.speech.RecognizerIntent;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;

import java.util.ArrayList;

/**
 * Created by MTartin on 27/5/2015.
 */
public abstract class Voice extends Activity implements View.OnClickListener {
    ListView lv;
    static final int check = 1111;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        lv = (ListView)findViewById(R.id.lvVoiceReturn);
        Button b = (Button)findViewById(R.id.bVoice);
        b.setOnClickListener(this);
    }



    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    //@Override
    public void OnClick(View v){
        Intent i = new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH);
        i.putExtra(RecognizerIntent.EXTRA_LANGUAGE_MODEL, RecognizerIntent.LANGUAGE_MODEL_FREE_FORM);
        i.putExtra(RecognizerIntent.EXTRA_PROMPT, "speak up son!");
        startActivityForResult(i, check);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data){
        if(requestCode == check && resultCode == RESULT_OK){
            ArrayList<String> results = data.getStringArrayListExtra(RecognizerIntent.EXTRA_RESULTS);
            lv.setAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, results));
        }
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}


<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" >

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Speak"
        android:id="@+id/bVoice" />
    <ListView android:layout_height="fill_parent" android:id="@+id/lvVoiceReturn"
        android:layout_width="match_parent" android:layout_weight="1.44"></ListView>
</LinearLayout>

Answer 1

remove this public abstract class MainActivity and use the previous one classpublic class MainActivity and create a different class public abstract class MyDiffclass and use that codes in it