Clickable ListView Items

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package com.o1.android.view;

import java.util.ArrayList;
import java.util.List;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;

/**
 * This list adapter is derived from the "Efficient List Adapter"-Example of
 * API-Demos. It uses holder object to access the list items efficiently.
 * Additionally, click listeners are provided, which can be connected to the
 * arbitrary view items, e.g. customized checkboxes, or other clickable
 * Image/TextViews. Implement subclasses of them and add your listeners to your
 * "clickable" views.
 * 
 * @author poss3x
 */
public abstract class ClickableListAdapter extends BaseAdapter {
	private LayoutInflater mInflater;
	private List mDataObjects; // our generic object list
	private int mViewId;

	/**
	 * This is the holder will provide fast access to arbitrary objects and
	 * views. Use a subclass to adapt it for your personal needs.
	 */
	public static class ViewHolder {
		// back reference to our list object
		public Object data;
	}

	/**
	 * The click listener base class.
	 */
	public static abstract class OnClickListener implements
			View.OnClickListener {

		private ViewHolder mViewHolder;

		/**
		 * @param holder The holder of the clickable item
		 */
		public OnClickListener(ViewHolder holder) {
			mViewHolder = holder;
		}

		// delegates the click event
		public void onClick(View v) {
			onClick(v, mViewHolder);
		}

		/**
		 * Implement your click behavior here
		 * @param v  The clicked view.
		 */
		public abstract void onClick(View v, ViewHolder viewHolder);
	};

	/**
	 * The long click listener base class.
	 */
	public static abstract class OnLongClickListener implements
			View.OnLongClickListener {
		private ViewHolder mViewHolder;

		/**
		 * @param holder The holder of the clickable item
		 */
		public OnLongClickListener(ViewHolder holder) {
			mViewHolder = holder;
		}

		// delegates the click event
		public boolean onLongClick(View v) {
			onLongClick(v, mViewHolder);
			return true;
		}

		/**
		 * Implement your click behavior here
		 * @param v  The clicked view.
		 */
		public abstract void onLongClick(View v, ViewHolder viewHolder);

	};

	/**
	 * @param context The current context
	 * @param viewid The resource id of your list view item
	 * @param objects The object list, or null, if you like to indicate an empty
	 * list
	 */
	public ClickableListAdapter(Context context, int viewid, List objects) {

		// Cache the LayoutInflate to avoid asking for a new one each time.
		mInflater = LayoutInflater.from(context);
		mDataObjects = objects;
		mViewId = viewid;

		if (objects == null) {
			mDataObjects = new ArrayList<Object>();
		}
	}

	/**
	 * The number of objects in the list.
	 */
	public int getCount() {
		return mDataObjects.size();
	}

	/**
	 * @return We simply return the object at position of our object list Note,
	 *         the holder object uses a back reference to its related data
	 *         object. So, the user usually should use {@link ViewHolder#data}
	 *         for faster access.
	 */
	public Object getItem(int position) {
		return mDataObjects.get(position);
	}

	/**
	 * We use the array index as a unique id. That is, position equals id.
	 * 
	 * @return The id of the object
	 */
	public long getItemId(int position) {
		return position;
	}

	/**
	 * Make a view to hold each row. This method is instantiated for each list
	 * object. Using the Holder Pattern, avoids the unnecessary
	 * findViewById()-calls.
	 */
	public View getView(int position, View view, ViewGroup parent) {
		// A ViewHolder keeps references to children views to avoid uneccessary
		// calls
		// to findViewById() on each row.
		ViewHolder holder;

		// When view is not null, we can reuse it directly, there is no need
		// to reinflate it. We only inflate a new View when the view supplied
		// by ListView is null.
		if (view == null) {

			view = mInflater.inflate(mViewId, null);
			// call the user's implementation
			holder = createHolder(view);
			// we set the holder as tag
			view.setTag(holder);

		} else {
			// get holder back...much faster than inflate
			holder = (ViewHolder) view.getTag();
		}

		// we must update the object's reference
		holder.data = getItem(position);
		// call the user's implementation
		bindHolder(holder);

		return view;
	}

	/**
	 * Creates your custom holder, that carries reference for e.g. ImageView
	 * and/or TextView. If necessary connect your clickable View object with the
	 * PrivateOnClickListener, or PrivateOnLongClickListener
	 * 
	 * @param vThe view for the new holder object
	 */
	protected abstract ViewHolder createHolder(View v);

	/**
	 * Binds the data from user's object to the holder
	 * @param h  The holder that shall represent the data object.
	 */
	protected abstract void bindHolder(ViewHolder h);
}


// -------------------------------------------------------------
//                      E X A M P L E
// -------------------------------------------------------------

// LAYOUT FILE

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
  android:orientation="horizontal"
  android:gravity="center_vertical"
  >
  
<TextView android:text="Text" android:id="@+id/listitem_text"
			android:layout_weight="1" 
			android:layout_width="fill_parent" 
			android:layout_height="wrap_content"
			></TextView>
<ImageView android:id="@+id/listitem_icon"
			android:src="@drawable/globe2_32x32"
			android:layout_width="wrap_content" 
			android:layout_height="wrap_content"
			android:maxWidth="32px"
			android:maxHeight="32px"
			>
</ImageView>
</LinearLayout>



//--------------------------------------------------------------
// ACTIVITY
//--------------------------------------------------------------
package com.o1.android.view;
import java.util.ArrayList;
import java.util.List;
import android.app.ListActivity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.view.View;
import android.widget.ImageView;
import android.widget.TextView;
import com.o1.android.view.ClickableListAdapter;
import com.o1.android.view.ClickableListAdapter.ViewHolder;

/**
 * An example how to implement the ClickableListAdapter for a list view layout containing
 * a TextView and an ImageView.
 * @author poss3x
 */
public class ClickableListItemActivity extends ListActivity {

	/**
	 * Our data class. This data will be bound to 
	 * MyViewHolder, which in turn is used for the 
	 * ListView. 
	 */
	static class MyData {
		public MyData(String t, boolean e) {
			text = t;
			enable = e;
		}

		String text;
		boolean enable;
	}
	
	/**
	 * Our very own holder referencing the view elements
	 * of our ListView layout
	 */
	static class MyViewHolder extends ViewHolder {

		public MyViewHolder(TextView t, ImageView i) {
			text = t;
			icon = i;
		}
		TextView text;
		ImageView icon;
	}

	/**
	 * The implementation of ClickableListAdapter
	 */
	private class MyClickableListAdapter extends ClickableListAdapter {
		public MyClickableListAdapter(Context context, int viewid,
				List<MyData> objects) {
			super(context, viewid, objects);
			// nothing to do
		}

		protected void bindHolder(ViewHolder h) {
			// Binding the holder keeps our data up to date.
			// In contrast to createHolder this method is called for all items
			// So, be aware when doing a lot of heavy stuff here.
			// we simply transfer our object's data to the list item representatives
			MyViewHolder mvh = (MyViewHolder) h;
			MyData mo = (MyData)mvh.data; 
			mvh.icon.setImageBitmap(
					mo.enable ? ClickableListItemActivity.this.mIconEnabled
							: ClickableListItemActivity.this.mIconDisabled);
			mvh.text.setText(mo.text);

		}

		@Override
		protected ViewHolder createHolder(View v) {
			// createHolder will be called only as long, as the ListView is not filled
			// entirely. That is, where we gain our performance:
			// We use the relatively costly findViewById() methods and
			// bind the view's reference to the holder objects.
			TextView text = (TextView) v.findViewById(R.id.listitem_text);
			ImageView icon = (ImageView) v.findViewById(R.id.listitem_icon);
			ViewHolder mvh = new MyViewHolder(text, icon);

			// Additionally, we make some icons clickable
			// Mind, that item becomes clickable, when adding a click listener (see API)
			// so, it is not necessary to use the android:clickable attribute in XML
			icon.setOnClickListener(new ClickableListAdapter.OnClickListener(mvh) {

				public void onClick(View v, ViewHolder viewHolder) {
					// we toggle the enabled state and also switch the icon
					MyViewHolder mvh = (MyViewHolder) viewHolder;
					MyData mo = (MyData) mvh.data;
					mo.enable = !mo.enable; // toggle
					ImageView icon = (ImageView) v;
					icon.setImageBitmap(
							mo.enable ? ClickableListItemActivity.this.mIconEnabled
									: ClickableListItemActivity.this.mIconDisabled);
				}
			});

			// for text we implement a long click listener
			text.setOnLongClickListener(new ClickableListAdapter.OnLongClickListener(mvh) {

				@Override
				public void onLongClick(View v, ViewHolder viewHolder) {
					
					MyViewHolder mvh = (MyViewHolder) viewHolder;
					MyData mo = (MyData)mvh.data;
					
					// we toggle an '*' in our text element
					String s = mo.text;
					if (s.charAt(0) == '*') {
						mo.text = s.substring(1);
					} else {
						mo.text = '*' + s;
					}
					mvh.text.setText(mo.text);
				}

			});

			return mvh; // finally, we return our new holder
		}

	}

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

		// preloading our icons
		mIconEnabled = BitmapFactory.decodeResource(this.getResources(),
				R.drawable.globe2_32x32);
		mIconDisabled = BitmapFactory.decodeResource(this.getResources(),
				R.drawable.globe2_32x32_trans);
		
		// fill list with some items...
		// to demonstrate the performance we create a bunch of data objects
		for (int i = 0; i < 250; ++i) {
			mObjectList.add(new MyData("Some Text " + i, true));
		}
		//here we set our adapter
		setListAdapter(new MyClickableListAdapter(this,
				R.layout.clickablelistitemview, mObjectList));

	}

	// --------------- field section -----------------
	private Bitmap mIconEnabled;
	private Bitmap mIconDisabled;

	private List<MyData> mObjectList = new ArrayList<MyData>();

}