Java tutorial
/* * Copyright (C) 2006 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package os.ransj.adapter; import android.content.Context; import android.view.View; import android.view.ViewGroup; import android.view.LayoutInflater; import android.net.Uri; import android.widget.BaseAdapter; import android.widget.Checkable; import android.widget.Filter; import android.widget.Filterable; import android.widget.ImageView; import android.widget.TextView; import org.json.JSONArray; import org.json.JSONObject; import java.util.ArrayList; import java.util.List; /** * An easy adapter to map static data to views defined in an XML file. You can specify the data * backing the list as an ArrayList of Maps. Each entry in the ArrayList corresponds to one row * in the list. The Maps contain the data for each row. You also specify an XML file that * defines the views used to display the row, and a mapping from keys in the Map to specific * views. * * Binding data to views occurs in two phases. First, if a * {@link android.widget.SimpleAdapter.ViewBinder} is available, * {@link SimpleJsonAdapter.ViewBinder#setViewValue(android.view.View, Object, String)} * is invoked. If the returned value is true, binding has occurred. * If the returned value is false, the following views are then tried in order: * <ul> * <li> A view that implements Checkable (e.g. CheckBox). The expected bind value is a boolean. * <li> TextView. The expected bind value is a string and {@link #setViewText(android.widget.TextView, String)} * is invoked. * <li> ImageView. The expected bind value is a resource id or a string and * {@link #setViewImage(android.widget.ImageView, int)} or {@link #setViewImage(android.widget.ImageView, String)} is invoked. * </ul> * If no appropriate binding can be found, an {@link IllegalStateException} is thrown. */ public class SimpleJsonAdapter extends BaseAdapter implements Filterable { private int[] mTo; private String[] mFrom; private ViewBinder mViewBinder; private List<? extends JSONObject> mData; private int mResource; private int mDropDownResource; private LayoutInflater mInflater; private SimpleFilter mFilter; private ArrayList<JSONObject> mUnfilteredData; /** * Constructor * * @param context The context where the View associated with this SimpleJsonAdapter is running * @param data A List of Maps. Each entry in the List corresponds to one row in the list. The * Maps contain the data for each row, and should include all the entries specified in * "from" * @param resource Resource identifier of a view layout that defines the views for this list * item. The layout file should include at least those named views defined in "to" * @param from A list of column names that will be added to the Map associated with each * item. * @param to The views that should display column in the "from" parameter. These should all be * TextViews. The first N views in this list are given the values of the first N columns * in the from parameter. */ public SimpleJsonAdapter(Context context, List<? extends JSONObject> data, int resource, String[] from, int[] to) { mData = data; mResource = mDropDownResource = resource; mFrom = from; mTo = to; mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); } /** * Constructor * * @param context The context where the View associated with this SimpleJsonAdapter is running * @param data A List of Maps. Each entry in the List corresponds to one row in the list. The * Maps contain the data for each row, and should include all the entries specified in * "from" * @param resource Resource identifier of a view layout that defines the views for this list * item. The layout file should include at least those named views defined in "to" * @param from A list of column names that will be added to the Map associated with each * item. * @param to The views that should display column in the "from" parameter. These should all be * TextViews. The first N views in this list are given the values of the first N columns * in the from parameter. */ public SimpleJsonAdapter(Context context, JSONArray data, int resource, String[] from, int[] to) { mData = array2List(data); mResource = mDropDownResource = resource; mFrom = from; mTo = to; mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); } private List<JSONObject> array2List(JSONArray array) { List<JSONObject> result = new ArrayList<JSONObject>(); int len = array.length(); for (int i = 0; i < len; i++) { result.add(array.optJSONObject(i)); } return result; } /** * @see android.widget.Adapter#getCount() */ public int getCount() { return mData.size(); } /** * @see android.widget.Adapter#getItem(int) */ public Object getItem(int position) { return mData.get(position); } /** * @see android.widget.Adapter#getItemId(int) */ public long getItemId(int position) { return position; } /** * @see android.widget.Adapter#getView(int, android.view.View, android.view.ViewGroup) */ public View getView(int position, View convertView, ViewGroup parent) { return createViewFromResource(position, convertView, parent, mResource); } private View createViewFromResource(int position, View convertView, ViewGroup parent, int resource) { View v; if (convertView == null) { v = mInflater.inflate(resource, parent, false); } else { v = convertView; } bindView(position, v); return v; } /** * <p>Sets the layout resource to create the drop down views.</p> * * @param resource the layout resource defining the drop down views * @see #getDropDownView(int, android.view.View, android.view.ViewGroup) */ public void setDropDownViewResource(int resource) { this.mDropDownResource = resource; } @Override public View getDropDownView(int position, View convertView, ViewGroup parent) { return createViewFromResource(position, convertView, parent, mDropDownResource); } private void bindView(int position, View view) { final JSONObject dataSet = mData.get(position); if (dataSet == null) { return; } final ViewBinder binder = mViewBinder; final String[] from = mFrom; final int[] to = mTo; final int count = to.length; for (int i = 0; i < count; i++) { final View v = view.findViewById(to[i]); if (v != null) { final Object data = dataSet.opt(from[i]); String text = data == null ? "" : data.toString(); if (text == null) { text = ""; } boolean bound = false; if (binder != null) { bound = binder.setViewValue(v, data, text); } if (!bound) { if (v instanceof Checkable) { if (data instanceof Boolean) { ((Checkable) v).setChecked((Boolean) data); } else if (v instanceof TextView) { // Note: keep the instanceof TextView check at the bottom of these // ifs since a lot of views are TextViews (e.g. CheckBoxes). setViewText((TextView) v, text); } else { throw new IllegalStateException( v.getClass().getName() + " should be bound to a Boolean, not a " + (data == null ? "<unknown type>" : data.getClass())); } } else if (v instanceof TextView) { // Note: keep the instanceof TextView check at the bottom of these // ifs since a lot of views are TextViews (e.g. CheckBoxes). setViewText((TextView) v, text); } else if (v instanceof ImageView) { if (data instanceof Integer) { setViewImage((ImageView) v, (Integer) data); } else { setViewImage((ImageView) v, text); } } else { throw new IllegalStateException(v.getClass().getName() + " is not a " + " view that can be bounds by this SimpleJsonAdapter"); } } } } } /** * Returns the {@link SimpleJsonAdapter.ViewBinder} used to bind data to views. * * @return a ViewBinder or null if the binder does not exist * * @see #setViewBinder(android.widget.SimpleAdapter.ViewBinder) */ public ViewBinder getViewBinder() { return mViewBinder; } /** * Sets the binder used to bind data to views. * * @param viewBinder the binder used to bind data to views, can be null to * remove the existing binder * * @see #getViewBinder() */ public void setViewBinder(ViewBinder viewBinder) { mViewBinder = viewBinder; } /** * Called by bindView() to set the image for an ImageView but only if * there is no existing ViewBinder or if the existing ViewBinder cannot * handle binding to an ImageView. * * This method is called instead of {@link #setViewImage(android.widget.ImageView, String)} * if the supplied data is an int or Integer. * * @param v ImageView to receive an image * @param value the value retrieved from the data set * * @see #setViewImage(android.widget.ImageView, String) */ private void setViewImage(ImageView v, int value) { v.setImageResource(value); } /** * Called by bindView() to set the image for an ImageView but only if * there is no existing ViewBinder or if the existing ViewBinder cannot * handle binding to an ImageView. * * By default, the value will be treated as an image resource. If the * value cannot be used as an image resource, the value is used as an * image Uri. * * This method is called instead of {@link #setViewImage(android.widget.ImageView, int)} * if the supplied data is not an int or Integer. * * @param v ImageView to receive an image * @param value the value retrieved from the data set * * @see #setViewImage(android.widget.ImageView, int) */ private void setViewImage(ImageView v, String value) { try { v.setImageResource(Integer.parseInt(value)); } catch (NumberFormatException nfe) { v.setImageURI(Uri.parse(value)); } } /** * Called by bindView() to set the text for a TextView but only if * there is no existing ViewBinder or if the existing ViewBinder cannot * handle binding to a TextView. * * @param v TextView to receive text * @param text the text to be set for the TextView */ private void setViewText(TextView v, String text) { v.setText(text); } public Filter getFilter() { if (mFilter == null) { mFilter = new SimpleFilter(); } return mFilter; } /** * This class can be used by external clients of SimpleJsonAdapter to bind * values to views. * * You should use this class to bind values to views that are not * directly supported by SimpleJsonAdapter or to change the way binding * occurs for views supported by SimpleJsonAdapter. * * @see SimpleJsonAdapter#setViewImage(android.widget.ImageView, int) * @see SimpleJsonAdapter#setViewImage(android.widget.ImageView, String) * @see SimpleJsonAdapter#setViewText(android.widget.TextView, String) */ public static interface ViewBinder { /** * Binds the specified data to the specified view. * * When binding is handled by this ViewBinder, this method must return true. * If this method returns false, SimpleJsonAdapter will attempts to handle * the binding on its own. * * @param view the view to bind the data to * @param data the data to bind to the view * @param textRepresentation a safe String representation of the supplied data: * it is either the result of data.toString() or an empty String but it * is never null * * @return true if the data was bound to the view, false otherwise */ boolean setViewValue(View view, Object data, String textRepresentation); } /** * <p>An array filters constrains the content of the array adapter with * a prefix. Each item that does not start with the supplied prefix * is removed from the list.</p> */ private class SimpleFilter extends Filter { @Override protected FilterResults performFiltering(CharSequence prefix) { FilterResults results = new FilterResults(); if (mUnfilteredData == null) { mUnfilteredData = new ArrayList<JSONObject>(mData); } if (prefix == null || prefix.length() == 0) { ArrayList<JSONObject> list = mUnfilteredData; results.values = list; results.count = list.size(); } else { String prefixString = prefix.toString().toLowerCase(); ArrayList<JSONObject> unfilteredValues = mUnfilteredData; int count = unfilteredValues.size(); ArrayList<JSONObject> newValues = new ArrayList<JSONObject>(count); for (int i = 0; i < count; i++) { JSONObject h = unfilteredValues.get(i); if (h != null) { int len = mTo.length; for (int j = 0; j < len; j++) { String str = h.optString(mFrom[j]); String[] words = str.split(" "); int wordCount = words.length; for (int k = 0; k < wordCount; k++) { String word = words[k]; if (word.toLowerCase().startsWith(prefixString)) { newValues.add(h); break; } } } } } results.values = newValues; results.count = newValues.size(); } return results; } @Override protected void publishResults(CharSequence constraint, FilterResults results) { //noinspection unchecked mData = (List<JSONObject>) results.values; if (results.count > 0) { notifyDataSetChanged(); } else { notifyDataSetInvalidated(); } } } }