Remove GridView items at run time if two items have same images

Question

i am developing a project where i compare two item images,So if two items will have same image after clicking these items it should be permanently delete from the GridView. my code is given below and this code encounter a problem. please any one help me.

MainActivity.java

 public class MainActivity extends Activity {
    Context ctx;
    int imagesArray[];
    GridViewContent adapter;
    List<Integer> pictures, pictureList;
    boolean flage = false;
    int save1, save2;
    int img1 = -1, img2 = -1;
    public int OriginalArray[] = { R.drawable.sample_0, R.drawable.sample_1,
            R.drawable.sample_2, R.drawable.sample_3, R.drawable.sample_0,
            R.drawable.sample_1, R.drawable.sample_2, R.drawable.sample_3 };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        shuffleArray();
        final GridView grid = (GridView) findViewById(R.id.gv_memory);
        grid.setAdapter(new GridViewContent(this));
    }

    private void shuffleArray() {
        // TODO Auto-generated method stub
        pictures = new ArrayList<Integer>();
        for (int index = 0; index < OriginalArray.length; index++) {
            pictures.add(OriginalArray[index]);
        }
        Collections.shuffle(pictures);
    }
    public class GridViewContent extends BaseAdapter {
        private Context context;
        private List<Integer> pictureList = new ArrayList<Integer>();

        public GridViewContent(Context c) {
            context = c;
            for (int i = 0; i < 8; i++) {
                pictureList.add(R.drawable.question);
            }
        }

        @Override
        public int getCount() {
            // TODO Auto-generated method stub
            return (pictureList.size());
        }

        @Override
        public Object getItem(int position) {
            // TODO Auto-generated method stub
            return pictureList.get(position);
        }
        @Override
        public long getItemId(int position) {
            // TODO Auto-generated method stub
            return position;
        }
        @Override
        public View getView(final int position, final View arg1,
                final ViewGroup arg2) {
            // TODO Auto-generated method stub
            final ImageView myimage = new ImageView(context);
            myimage.setImageResource(pictureList.get(position));
            // myimage.setImageResource(pictures.get(pictureArray[position]));
            myimage.setScaleType(ImageView.ScaleType.CENTER_INSIDE);
            myimage.setLayoutParams(new GridView.LayoutParams(70, 70));
            final GridView grid = (GridView) findViewById(R.id.gv_memory);
            myimage.setOnClickListener(new OnClickListener() {

                @Override
                public void onClick(View v) {
                    myimage.setImageResource(pictures.get(position));
                    // View v1 = new View(context);
                    if (flage == false) {

                        img1 = pictures.get(position);
                        // v1 = arg2.getChildAt(position);
                        save1 = position;
                        flage = true;

                    } else if (flage == true) {

                        img2 = pictures.get(position);
                        save2 = position;
                        checkResult(save1, save2);
                        flage = false;
                    }
                    // else if(f)
                }
            });

            return myimage;
        }

    }

    public void checkResult(int s1, int s2) {
        if (img1 == img2) {
            pictureList.remove(s1); //this is line no 116
            pictureList.remove(s1);
            adapter.notifyDataSetChanged();
            Toast.makeText(MainActivity.this, "Congratualatin !!!!",
                    Toast.LENGTH_LONG).show();
        } else {
            Toast.makeText(MainActivity.this, "Sorry!!!!", Toast.LENGTH_LONG)
                    .show();
            final GridView grid = (GridView) findViewById(R.id.gv_memory);
            grid.setAdapter(new GridViewContent(this));
        }

    }
}      

LogCat.

03-14 01:07:12.791: D/dalvikvm(1598): GC_FOR_ALLOC freed 38K, 7% free 2771K/2980K, paused 183ms, total 185ms
03-14 01:07:12.811: I/dalvikvm-heap(1598): Grow heap (frag case) to 3.943MB for 1127536-byte allocation
03-14 01:07:12.941: D/dalvikvm(1598): GC_FOR_ALLOC freed 2K, 6% free 3870K/4084K, paused 128ms, total 128ms
03-14 01:07:13.111: D/dalvikvm(1598): GC_FOR_ALLOC freed 4K, 5% free 4253K/4448K, paused 25ms, total 26ms
03-14 01:07:13.143: I/dalvikvm-heap(1598): Grow heap (frag case) to 5.688MB for 1440016-byte allocation
03-14 01:07:13.271: D/dalvikvm(1598): GC_FOR_ALLOC freed <1K, 4% free 5659K/5856K, paused 127ms, total 127ms
03-14 01:07:13.481: I/Choreographer(1598): Skipped 49 frames!  The application may be doing too much work on its main thread.
03-14 01:07:13.571: D/gralloc_goldfish(1598): Emulator without GPU emulation detected.
03-14 01:08:36.011: D/dalvikvm(1598): GC_FOR_ALLOC freed 357K, 9% free 5587K/6116K, paused 34ms, total 35ms
03-14 01:08:36.021: I/dalvikvm-heap(1598): Grow heap (frag case) to 6.543MB for 971296-byte allocation
03-14 01:08:36.154: D/dalvikvm(1598): GC_FOR_ALLOC freed 1K, 8% free 6534K/7068K, paused 123ms, total 123ms
03-14 01:08:39.422: D/dalvikvm(1598): GC_FOR_ALLOC freed 2385K, 8% free 5419K/5876K, paused 76ms, total 78ms
03-14 01:08:39.492: D/dalvikvm(1598): GC_FOR_ALLOC freed 1K, 4% free 5654K/5876K, paused 40ms, total 41ms
03-14 01:08:41.352: D/AndroidRuntime(1598): Shutting down VM
03-14 01:08:41.352: W/dalvikvm(1598): threadid=1: thread exiting with uncaught exception (group=0x41465700)
03-14 01:08:41.532: E/AndroidRuntime(1598): FATAL EXCEPTION: main
03-14 01:08:41.532: E/AndroidRuntime(1598): java.lang.NullPointerException
03-14 01:08:41.532: E/AndroidRuntime(1598):     at com.example.memoryforkids.MainActivity.checkResult(MainActivity.java:116)
03-14 01:08:41.532: E/AndroidRuntime(1598):     at com.example.memoryforkids.MainActivity$GridViewContent$1.onClick(MainActivity.java:102)
03-14 01:08:41.532: E/AndroidRuntime(1598):     at android.view.View.performClick(View.java:4240)
03-14 01:08:41.532: E/AndroidRuntime(1598):     at android.view.View$PerformClick.run(View.java:17721)
03-14 01:08:41.532: E/AndroidRuntime(1598):     at android.os.Handler.handleCallback(Handler.java:730)
03-14 01:08:41.532: E/AndroidRuntime(1598):     at android.os.Handler.dispatchMessage(Handler.java:92)
03-14 01:08:41.532: E/AndroidRuntime(1598):     at android.os.Looper.loop(Looper.java:137)
03-14 01:08:41.532: E/AndroidRuntime(1598):     at android.app.ActivityThread.main(ActivityThread.java:5103)
03-14 01:08:41.532: E/AndroidRuntime(1598):     at java.lang.reflect.Method.invokeNative(Native Method)
03-14 01:08:41.532: E/AndroidRuntime(1598):     at java.lang.reflect.Method.invoke(Method.java:525)
03-14 01:08:41.532: E/AndroidRuntime(1598):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
03-14 01:08:41.532: E/AndroidRuntime(1598):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
03-14 01:08:41.532: E/AndroidRuntime(1598):     at dalvik.system.NativeStart.main(Native Method)

main.xml

<?xml version="1.0" encoding="utf-8"?>
<GridView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/gv_memory"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:columnWidth="90dp"
    android:gravity="center"
    android:horizontalSpacing="10dp"
    android:numColumns="auto_fit"
    android:stretchMode="columnWidth"
    android:verticalSpacing="10dp" >

</GridView>      

Thanks in advance..

Answer 1

Ok so, I found the bug, you have defined the pictureList variable in two places, the one being initialized inside the adapter class is a local variable. When checkResult is called, it uses the pictureList variable belonging to the main activity class. Do the following:

1) Remove the local variable inside the adapter class. 2) Initialize the pictureList variable that has been defined in the activity class.

This fixes the error. Its working fine on my machine now!

Also, there are a lot of issues with the logic you are using, you will realize that once you fix this error.