GridView Picture Array Null Pointer Exception

Question

This is a homework assignment. I can't figure out why I am getting a null pointer exception. By the way, I pretty much copied the code for the MainActivity from the textbook. I already found one typo. I am hoping there is another, because I can't figure out why this won't work.

It's an eight item gridview photo album. The top of the home screen is the grid view of pictures, the bottom is a single picture which is supposed to show when the user clicks on the selected picture.

I checked the XML for incorrect ids. What am I missing? The Java first, then the XML. Thanks.

MainActivity.java

package com.nancy.example.myphotoalbum;

import android.content.Context;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {
    Integer[] myPhotos = {R.drawable.brainvessels, R.drawable.flowers, R.drawable.flowerstwo,
            R.drawable.hannahandme, R.drawable.jellies, R.drawable.flowersthree, R.drawable.littledragon, R.drawable.pluto};
    ImageView pic;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        GridView grid = (GridView) findViewById(R.id.photoGrid);
        grid.setAdapter(new ImageAdapter(this));
        final ImageView pic = (ImageView) findViewById(R.id.imgLarge);

        grid.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent,
                                    View view, int position, long id) {

                Toast.makeText(getBaseContext(), "Select Picture " + (position + 1), Toast.LENGTH_LONG).show();
                pic.setImageResource(myPhotos[position]);
            }

        });

    }

    public class ImageAdapter extends BaseAdapter {
        private Context context;

        public ImageAdapter(Context c) {
            context = c;}



            @Override
            public int getCount () {
                return myPhotos.length;
            }


            @Override
            public Object getItem ( int position){
                return null;
            }


            @Override
            public long getItemId ( int position){
                return 0;
            }


            @Override
            public View getView ( int position, View convertView, ViewGroup parent){
                pic = new ImageView(context);
                pic.setImageResource(myPhotos[position]);
                pic.setScaleType(ImageView.ScaleType.FIT_XY);
                pic.setLayoutParams(new GridView.LayoutParams(250, 230));
                return pic;
            }


        }
    }

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:background="@drawable/photogradient"
    android:orientation="vertical"
    tools:context="com.nancy.example.myphotoalbum.MainActivity">


    <GridView
        android:layout_width="wrap_content"
        android:layout_height="200dp"
        android:id="@+id/photoGrid"
        android:layout_alignParentTop = "true"
        android:layout_alignParentLeft = "true"
        android:layout_alignParentStart = "true"
        android:numColumns = "auto_fit"
        android:columnWidth = "120dp"
        android:horizontalSpacing="5dp"
        android:verticalSpacing="5dp"/>

    <ImageView
        android:layout_width="270dp"
        android:layout_marginTop="10dp"
        android:layout_height="300dp"
        android:id="@+id/imgLarge"
        android:layout_gravity="center_horizontal"
        android:contentDescription="@string/imgLarge"/>



</LinearLayout>

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Nancy Melucci

Nancy Melucci

GridView Picture Array Null Pointer Exception