ViewHolder + ButterKnife

gistfile1.java

package com.ohhstudio.mitc.inventory;

import android.content.ContentUris;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.net.Uri;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.CursorAdapter;
import android.widget.TextView;
import android.widget.Toast;

import com.ohhstudio.mitc.inventory.data.ItemContract.ItemEntry;

import butterknife.BindView;
import butterknife.ButterKnife;

/**
 * This is an adapter for a list or grid view
 * that uses a Cursor of item data as its data source. This adapter knows
 * how to create list items for each row of item data in the Cursor.
 */
public class ItemCursorAdapter extends CursorAdapter {

    // Number of current item's quantity
    private int mQuantity;

    // The view's context
    private Context mContext;

    // Item's name in String
    private String mNameString;

    // Item's price in String
    private String mPriceString;

    // Item's quantity in String
    private String quantityString;

    // Item's id in the table
    private int mItemId;



    /**
     * Constructs a new ItemCursorAdapter.
     *
     * @param context The context
     * @param c       The cursor from which to get the data.
     */
    public ItemCursorAdapter(Context context, Cursor c) {
        super(context, c, 0 /* flags */);
    }

    /**
     * Makes a new blank list item view. No data is set (or bound) to the views yet.
     *
     * @param context app context
     * @param cursor  The cursor from which to get the data. The cursor is already
     *                moved to the correct position.
     * @param parent  The parent to which the new view is attached to
     * @return the newly created list item view.
     */
    @Override
    public View newView(Context context, Cursor cursor, ViewGroup parent) {
        // Inflate a list item view using the layout specified in list_item.xml
        View view = LayoutInflater.from(context).inflate(R.layout.list_item, parent, false);
        ViewHolder holder = new ViewHolder(view);
        view.setTag(holder);
        return view;
    }

    /**
     * Custom view holder to hold buttons for each item row in the list
     */
    static class ViewHolder {
        @BindView(R.id.item_name) TextView nameTextView;
        @BindView(R.id.item_price) TextView priceTextView;
        @BindView(R.id.item_quantity) TextView quantityTV;
        @BindView(R.id.button_sale) Button saleButton;
        public ViewHolder(View view) {
            ButterKnife.bind(this, view);
        }
    }

    /**
     * This method binds the item data (in the current row pointed to by cursor) to the given
     * list item layout. For example, the name for the current item can be set on the name TextView
     * in the list item layout.
     *
     * @param view    Existing view, returned earlier by newView() method
     * @param context app context
     * @param cursor  The cursor from which to get the data. The cursor is already moved to the
     *                correct row.
     */
    @Override
    public void bindView(View view, Context context, Cursor cursor) {
        // Get context
        mContext = context;
        final ViewHolder holder = (ViewHolder) view.getTag();

        // Get item id for updating item quantity
        int itemIdIndex = cursor.getColumnIndex(ItemEntry._ID);
        mItemId = cursor.getInt(itemIdIndex);

        // Find the columns of item attributes that we're interested in
        int nameColumnIndex = cursor.getColumnIndex(ItemEntry.COLUMN_ITEM_NAME);
        int quantityColumnIndex = cursor.getColumnIndex(ItemEntry.COLUMN_ITEM_QUANTITY);
        int priceColumnIndex = cursor.getColumnIndex(ItemEntry.COLUMN_ITEM_PRICE);

        // Read the item attributes from the Cursor for the current item
        mNameString = cursor.getString(nameColumnIndex);
        quantityString = cursor.getString(quantityColumnIndex);
        mPriceString = cursor.getString(priceColumnIndex);

        // Update the TextViews with the attributes for the current item
        holder.nameTextView.setText(mNameString);
        holder.quantityTV.setText(quantityString);
        holder.priceTextView.setText(mPriceString);

        // Clicking the Sale button subtracts one from item quantity
        // then save it to the database
        holder.saleButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // Get current quantity
                mQuantity = Integer.parseInt(holder.quantityTV.getText().toString().trim());

                // Only modify quantity if it's greater than 0
                if (mQuantity > 0) {
                    // Minus one from item's quantity
                    mQuantity--;
                    // Display updated quantity
                    String quantity = Integer.toString(mQuantity);
                    quantityString = quantity;
                    holder.quantityTV.setText(quantity);

                    // Save the item with the new quantity
                    saveItem();
                } else {
                    Toast.makeText(mContext, "This item has 0 quantity, can't sell.",
                            Toast.LENGTH_SHORT).show();
                }
            }
        });
    }

    // Save the item with new quantity
    private void saveItem() {
        ContentValues values = new ContentValues();

        // Store updated quantity of the current item
        values.put(ItemEntry.COLUMN_ITEM_QUANTITY, quantityString);

        // Create uri for current item with item id
        Uri currentItemUri = ContentUris.withAppendedId(ItemEntry.CONTENT_URI, mItemId);

        // Update the item's quantity in the database
        int rowEffected = mContext.getContentResolver().update(currentItemUri, values, null, null);
    }
}