Question

I have a GridView with 9 items. What I’m trying to do is when I click an item, its icon changes. The way I’m doing it returns

java.lang.ClassCastException: android.widget.LinearLayout

I have to classes:

MainLayout.java

public class MainLayout extends Activity implements OnItemClickListener
{   

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        requestWindowFeature(Window.FEATURE_NO_TITLE);

        setContentView(R.layout.mainlayout);

        getWindow().setFeatureInt(Window.FEATURE_CUSTOM_TITLE, R.layout.window_title);      

         final ImageButton btn=(ImageButton)findViewById(R.id.logoimagebutton);
         btn.setBackgroundColor(Color.TRANSPARENT);

         btn.setOnTouchListener(new OnTouchListener() {

                public boolean onTouch(View v, MotionEvent event) {
                    if (event.getAction() == MotionEvent.ACTION_DOWN ) {
                        btn.setImageResource(R.drawable.logoselected);
                        Toast.makeText(getApplicationContext(), "Clicked", Toast.LENGTH_SHORT).show();
                        //return true;
                    }else if (event.getAction() == MotionEvent.ACTION_UP) {
                        btn.setImageResource(R.drawable.logo);
                    }

                    return false;
                }
            });

        final GridView gridview = (GridView) findViewById(R.id.gridview);
        gridview.setAdapter(new ImageAdapter(this));            

        gridview.setOnItemClickListener(new OnItemClickListener()
        {
            public void onItemClick(AdapterView<?> parent, View v, int position, long id)
            {                   
                ImageView imageView = (ImageView) v;
                imageView.setImageResource(ImageAdapter.mThumbSelected[position]);
            }
        });   
    }

    @Override
    public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3)
    {
        // TODO Auto-generated method stub

    }

}

ImageAdapter.java

public class ImageAdapter extends BaseAdapter
{

    private Context mContext;

    public static Integer[] mThumbIds = 
    {
            //a collection of images
    };

    public static Integer[] mThumbSelected = 
    {
            //a collection of images
    };

    private String[] mLabelsIds = {//a collection of strings};

    public ImageAdapter(Context c)
    {
        // TODO Auto-generated constructor stub
        mContext = c;
    }

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

    @Override
    public Object getItem(int arg0)
    {
        // TODO Auto-generated method stub
        return mThumbIds[arg0];
    }

    @Override
    public long getItemId(int arg0)
    {
        // TODO Auto-generated method stub
        return arg0;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent)
    {       
        View grid;

        if (convertView == null)
        {
            grid = new View(mContext);
            LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            grid = inflater.inflate(R.layout.menugrid, parent, false);
        } else
        {
            grid = (View) convertView;
        }

        ImageView imageView = (ImageView) grid.findViewById(R.id.imageicon);
        TextView textView = (TextView) grid.findViewById(R.id.imagelabel);
        imageView.setImageResource(mThumbIds[position]);
        textView.setText(mLabelsIds[position]);

        return grid;
    }
}

Here is my two xml files:

menugrid.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:orientation="vertical">

     <ImageView
      android:id="@+id/imageicon"
      android:layout_width="fill_parent"
      android:layout_height="fill_parent"
      />
     <TextView
      android:id="@+id/imagelabel"
      android:layout_width="fill_parent"
      android:layout_height="fill_parent"     
      android:textColor="#000000"
      android:textSize="16px"
      android:gravity="center_horizontal"/>
</LinearLayout>

mainlayout.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/mainlayout"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" 
    android:orientation="vertical"
    android:background="@drawable/background">

    <LinearLayout
        android:id="@+id/holdlogo"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"    
        android:orientation="horizontal"                    
        android:background="@drawable/title_background">

        <ImageButton
            android:id="@+id/logoimagebutton"
            android:scaleType="center"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"    
            android:layout_gravity="center_vertical"    
            android:src="@drawable/logo"
            >
        </ImageButton>

    </LinearLayout>


    <GridView xmlns:android="http://schemas.android.com/apk/res/android" 
    android:id="@+id/gridview"
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent"
    android:numColumns="auto_fit"
    android:layout_marginTop="10px"
    android:verticalSpacing="10dp"
    android:horizontalSpacing="10dp"
    android:columnWidth="90dp"
    android:stretchMode="columnWidth"
    android:gravity="center"
/>  
</LinearLayout>

Can anyone tell me what is wrong in my code? Or How to change the image of an item when pressing it? I think onTouchListener is more efficient, due to the fact that it has the event, so when event.getAction() == MotionEvent.ACTION_DOWN I show the image and when event.getAction() == MotionEvent.ACTION_UP I show the original icon.

Thanks in advance.

Answer 1

I guess you reveice the ClassCastException here:

   public void onItemClick(AdapterView<?> parent, View v, int position, long id)
        {                   
            ImageView imageView = (ImageView) v;
            imageView.setImageResource(ImageAdapter.mThumbSelected[position]);
        }

The View sent is actually the LinearLayout in which the ImageView resides in. You need to get the item using the int position and then manipulate it to your needs, or get the ImageView inside the LinearLayout, which is your Grid Item Layout.