Ytukyg

I have a problem that I'm at whit's end to solve:

I'm working on a program in Android Studio that essentially cycles through a list of storyboards (Like a slideshow) and I'm using a viewPager component to do so. It's sorta cool because I don't need buttons. I can just swipe (Though I'm working on setting up some)However, I'm also trying to link the "slides" in the show with sound (In this case, the storyboard audio). The issue is that the app is crashing and it's giving me some null error in logcat. This is what I've did so far . . .

I've create a slideAdapter Activity:

package com.example.******.*************;

import android.content.Context;

import android.support.v4.view.PagerAdapter;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.view.LayoutInflater;

import android.view.View;

import android.view.ViewGroup;

import android.widget.ImageView;

import android.widget.LinearLayout;



public class SlideAdapter extends PagerAdapter {



    Context context;

    LayoutInflater inflater;



    // List of Images



    public int lst_storyboard = {

            R.drawable.imgmob02, R.drawable.imgmob03, R.drawable.imgmob04,

            R.drawable.imgmob05, R.drawable.imgmob06, R.drawable.imgmob07,

            R.drawable.imgmob08, R.drawable.imgmob09, R.drawable.imgmob010,

            R.drawable.imgmob011,R.drawable.imgmob012,R.drawable.imgmob013

    };



    // List of mp3 raw audio



    public int lst_audio_eng = {

            R.raw.audio_eng_01, R.raw.audio_eng_02, R.raw.audio_eng_03,

            R.raw.audio_eng_04, R.raw.audio_eng_05, R.raw.audio_eng_06,

            R.raw.audio_eng_07, R.raw.audio_eng_08, R.raw.audio_eng_09,

            R.raw.audio_eng_010, R.raw.audio_eng_011, R.raw.audio_eng_012

    };



    public SlideAdapter(Context context) {

        this.context = context;

    }



    @Override

    public int getCount() {

        return lst_storyboard.length;

    }



    @Override

    public boolean isViewFromObject(View view, Object object) {

        return (view==(LinearLayout)object);

    }



    @Override

    public Object instantiateItem(ViewGroup container, int position) {

        inflater = (LayoutInflater) context.getSystemService(context.LAYOUT_INFLATER_SERVICE);

        View view = inflater.inflate(R.layout.activity_slide_adapter,container,false);

        LinearLayout layoutslide = (LinearLayout) view.findViewById(R.id.slidelinearlayout);

        ImageView imgslide = (ImageView)  view.findViewById(R.id.slideimg);



        imgslide.setImageResource(lst_storyboard[position]);





        container.addView(view);

        return view;

    }



    @Override

    public void destroyItem(ViewGroup container, int position, Object object) {

        container.removeView((LinearLayout)object);

    }



}

And this is the slideactivity.xml:

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout

    xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:orientation="vertical"

    android:gravity="center"

    android:id="@+id/slidelinearlayout">



    <ImageView

        android:layout_width="match_parent"

        android:layout_height="match_parent"

        android:id="@+id/slideimg"

        android:contentDescription="@string/todo" />

</LinearLayout>

This is the mainActivity file:

    package com.example.******.***********;



import android.media.MediaPlayer;

import android.support.v4.view.ViewPager;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;



import static com.example.gman5541.childrensbookconcept2.SlideAdapter.lst_audio_eng;



public class MainActivity extends AppCompatActivity {

    private ViewPager viewPager;

    private SlideAdapter myadapter;



    private MediaPlayer mp;

    private MediaPlayer BG;





    @Override

    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        myadapter = new SlideAdapter(this);

        viewPager = (ViewPager) findViewById(R.id.viewpager);



        viewPager.addOnPageChangeListener(player);



        viewPager.setAdapter(myadapter);

        viewPager.setCurrentItem(0);



        BG = MediaPlayer.create(getApplicationContext(), R.raw.audio_eng_01);

        BG.setLooping(true);

        BG.setVolume(100, 100);

        BG.start();

        mp = MediaPlayer.create(MainActivity.this,lst_audio_eng[0]);

        mp.start();

    }









    @Override

    protected void onPause() {

        super.onPause();

        BG.pause();

    }



    @Override

    protected void onResume() {

        super.onResume();

        BG.start();

    }



    public ViewPager.OnPageChangeListener player = new ViewPager.OnPageChangeListener() {



        @Override

        public void onPageSelected(int arg1)

        {

            mp = MediaPlayer.create(MainActivity.this, lst_audio_eng[arg1]);

            mp.start();

        }



        @Override

        public void onPageScrolled(int arg0, float arg1, int arg2)

        {

        }



        @Override

        public void onPageScrollStateChanged(int arg0)

        {

        }

    };



}

And it's xml file:

   <?xml version="1.0" encoding="utf-8"?>

<LinearLayout 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="com.example.gman5541.childrensbookconcept2.MainActivity">



    <android.support.v4.view.ViewPager

        android:id="@+id/viewpager"

        android:layout_width="match_parent"

        android:layout_height="match_parent">



    </android.support.v4.view.ViewPager>



</LinearLayout>

This is what I've got from the logcat debug:

--------- beginning of crash

2018-11-25 18:40:07.511 15354-15354/com.example.gman5541.childrensbookconcept2 E/AndroidRuntime: FATAL EXCEPTION: main

    Process: com.example.gman5541.childrensbookconcept2, PID: 15354

    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.gman5541.childrensbookconcept2/com.example.gman5541.childrensbookconcept2.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.media.MediaPlayer.setLooping(boolean)' on a null object reference

        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2778)

        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856)

        at android.app.ActivityThread.-wrap11(Unknown Source:0)

        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589)

        at android.os.Handler.dispatchMessage(Handler.java:106)

        at android.os.Looper.loop(Looper.java:164)

        at android.app.ActivityThread.main(ActivityThread.java:6494)

        at java.lang.reflect.Method.invoke(Native Method)

        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)

        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)

     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.media.MediaPlayer.setLooping(boolean)' on a null object reference

        at com.example.gman5541.childrensbookconcept2.MainActivity.onCreate(MainActivity.java:31)

        at android.app.Activity.performCreate(Activity.java:7009)

        at android.app.Activity.performCreate(Activity.java:7000)

        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1214)

        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2731)

        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856) 

        at android.app.ActivityThread.-wrap11(Unknown Source:0) 

        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589) 

        at android.os.Handler.dispatchMessage(Handler.java:106) 

        at android.os.Looper.loop(Looper.java:164) 

        at android.app.ActivityThread.main(ActivityThread.java:6494) 

        at java.lang.reflect.Method.invoke(Native Method) 

        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438) 

        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807) 

Though I'm also working on having a "play" button with a "sound" switch to switch sound on and off, Right now, I'm just trying to match one list (storyboards) with another list(audio). The Program works, if I comment out the MediaPlayer lines. Please help.