Java tutorial
/* * Copyright (c) 2014 Jono Vanhie-Van Gerwen * * 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 com.github.jvanhie.discogsscrobbler; import android.app.Activity; import android.os.Bundle; import android.support.v4.app.Fragment; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.AbsListView; import android.widget.ExpandableListView; import android.widget.FrameLayout; import android.widget.ListView; import android.widget.TextView; import com.github.jvanhie.discogsscrobbler.adapters.SearchAdapter; import com.github.jvanhie.discogsscrobbler.queries.DiscogsSearchLoader; import com.github.jvanhie.discogsscrobbler.queries.DiscogsSearchRelease; import com.github.jvanhie.discogsscrobbler.queries.DiscogsSearchResult; import com.github.jvanhie.discogsscrobbler.util.Discogs; import java.util.List; /** * A list fragment representing a list of Releases. This fragment * also supports tablet devices by allowing list items to be given an * 'activated' state upon selection. This helps indicate which item is * currently being viewed in a {@link com.github.jvanhie.discogsscrobbler.ReleaseDetailFragment}. * <p> * Activities containing this fragment MUST implement the {@link Callbacks} * interface. */ public class SearchFragment extends Fragment { /** * The serialization (saved instance state) Bundle key representing the * activated item position. Only used on tablets. */ private static final String STATE_ACTIVATED_POSITION = "activated_position"; /** * The fragment's current callback object, which is notified of list item * clicks. */ private Callbacks mCallbacks = sDummyCallbacks; /** * The current activated item position. Only used on tablets. */ private int mActivatedPosition = ListView.INVALID_POSITION; private ExpandableListView mList; private SearchAdapter mAdapter; private Discogs mDiscogs; private TextView mEmptyHeading; private TextView mEmptyText; /** * A callback interface that all activities containing this fragment must * implement. This mechanism allows activities to be notified of item * selections. */ public interface Callbacks { /** * Callback for when an item has been selected. */ public void onItemSelected(long id); public void setRefreshVisible(boolean visible); } /** * A dummy implementation of the {@link Callbacks} interface that does * nothing. Used only when this fragment is not attached to an activity. */ private static Callbacks sDummyCallbacks = new Callbacks() { @Override public void onItemSelected(long id) { } public void setRefreshVisible(boolean visible) { } }; /** * Mandatory empty constructor for the fragment manager to instantiate the * fragment (e.g. upon screen orientation changes). */ public SearchFragment() { } @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setRetainInstance(true); } @Override public void onViewCreated(View view, Bundle savedInstanceState) { super.onViewCreated(view, savedInstanceState); // Restore the previously serialized activated item position. if (savedInstanceState != null && savedInstanceState.containsKey(STATE_ACTIVATED_POSITION)) { setActivatedPosition(savedInstanceState.getInt(STATE_ACTIVATED_POSITION)); } } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { mList = new ExpandableListView(getActivity()); mList.setAdapter(mAdapter); mList.setOnGroupClickListener(new GroupClickHandler()); mList.setOnChildClickListener(new ExpandableListView.OnChildClickListener() { @Override public boolean onChildClick(ExpandableListView expandableListView, View view, final int i, int i2, long l) { if (l == 0) { //it's a loader (yes, hackish afterthought) get the necessary data from it DiscogsSearchLoader loader = (DiscogsSearchLoader) mAdapter.getChild(i, i2); mCallbacks.setRefreshVisible(true); if (loader.parenttype.equals("artist")) { mDiscogs.getArtistReleases(loader.parentid, loader.page, new Discogs.DiscogsDataWaiter<List<DiscogsSearchRelease>>() { @Override public void onResult(boolean success, List<DiscogsSearchRelease> data) { if (success) { mAdapter.addChildren(i, data); } mCallbacks.setRefreshVisible(false); } }); } else if (loader.parenttype.equals("label")) { mDiscogs.getLabelReleases(loader.parentid, loader.page, new Discogs.DiscogsDataWaiter<List<DiscogsSearchRelease>>() { @Override public void onResult(boolean success, List<DiscogsSearchRelease> data) { if (success) { mAdapter.addChildren(i, data); } mCallbacks.setRefreshVisible(false); } }); } else if (loader.parenttype.equals("master")) { mDiscogs.getMasterReleases(loader.parentid, loader.page, new Discogs.DiscogsDataWaiter<List<DiscogsSearchRelease>>() { @Override public void onResult(boolean success, List<DiscogsSearchRelease> data) { if (success) { mAdapter.addChildren(i, data); } mCallbacks.setRefreshVisible(false); } }); } } else { //normal release selected onItemSelected(l); } return false; } }); //create superframe for adding list and empty view FrameLayout superFrame = new FrameLayout(getActivity()); FrameLayout.LayoutParams layoutparams = new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT); superFrame.setLayoutParams(layoutparams); View emptyView = inflater.inflate(R.layout.fragment_empty, container, false); mEmptyHeading = ((TextView) emptyView.findViewById(R.id.empty_heading)); mEmptyHeading.setText("Start searching Discogs"); mEmptyText = ((TextView) emptyView.findViewById(R.id.empty_text)); mEmptyText.setText("Enter a query or scan a barcode"); if (mDiscogs == null) mDiscogs = Discogs.getInstance(getActivity()); mList.setGroupIndicator(null); superFrame.addView(emptyView); mList.setEmptyView(emptyView); superFrame.addView(mList); return superFrame; } public void search(String s) { mCallbacks.setRefreshVisible(true); mDiscogs.search(s, new Discogs.DiscogsDataWaiter<List<DiscogsSearchResult>>() { @Override public void onResult(boolean success, List<DiscogsSearchResult> data) { if (success) { //show results mEmptyHeading.setText("No results"); mEmptyText.setText("Discogs didn't return any matches, try a different query"); mAdapter = new SearchAdapter(getActivity(), data); mList.setAdapter(mAdapter); } mCallbacks.setRefreshVisible(false); } }); } public void search(String s, String type) { mCallbacks.setRefreshVisible(true); mDiscogs.search(s, type, new Discogs.DiscogsDataWaiter<List<DiscogsSearchResult>>() { @Override public void onResult(boolean success, List<DiscogsSearchResult> data) { if (success) { //show results mEmptyHeading.setText("No results"); mEmptyText.setText( "Discogs didn't return any matches, try a different query or adjust your filter"); mAdapter = new SearchAdapter(getActivity(), data); mList.setAdapter(mAdapter); } mCallbacks.setRefreshVisible(false); } }); } public void searchBarcode(String barcode) { mCallbacks.setRefreshVisible(true); mDiscogs.searchBarcode(barcode, new Discogs.DiscogsDataWaiter<List<DiscogsSearchResult>>() { @Override public void onResult(boolean success, List<DiscogsSearchResult> data) { if (success) { //show results mEmptyHeading.setText("No matches"); mEmptyText.setText( "Discogs didn't have a match on your barcode. This is not uncommon, check the correctness of your barcode or try a text search instead"); mAdapter = new SearchAdapter(getActivity(), data); mList.setAdapter(mAdapter); } mCallbacks.setRefreshVisible(false); } }); } @Override public void onAttach(Activity activity) { super.onAttach(activity); // Activities containing this fragment must implement its callbacks. if (!(activity instanceof Callbacks)) { throw new IllegalStateException("Activity must implement fragment's callbacks."); } mCallbacks = (Callbacks) activity; } @Override public void onDetach() { super.onDetach(); // Reset the active callbacks interface to the dummy implementation. mCallbacks = sDummyCallbacks; } public void onItemSelected(long id) { // Notify the active callbacks interface (the activity, if the // fragment is attached to one) that an item has been selected. mCallbacks.onItemSelected(id); } @Override public void onSaveInstanceState(Bundle outState) { super.onSaveInstanceState(outState); if (mActivatedPosition != ListView.INVALID_POSITION) { // Serialize and persist the activated item position. outState.putInt(STATE_ACTIVATED_POSITION, mActivatedPosition); } } /** * Turns on activate-on-click mode. When this mode is on, list items will be * given the 'activated' state when touched. */ public void setActivateOnItemClick(boolean activateOnItemClick) { // When setting CHOICE_MODE_SINGLE, ListView will automatically // give items the 'activated' state when touched. mList.setChoiceMode(activateOnItemClick ? AbsListView.CHOICE_MODE_SINGLE : AbsListView.CHOICE_MODE_NONE); } private void setActivatedPosition(int position) { if (position == AbsListView.INVALID_POSITION) { mList.setItemChecked(mActivatedPosition, false); } else { mList.setItemChecked(position, true); } mActivatedPosition = position; } private class GroupClickHandler implements ExpandableListView.OnGroupClickListener { @Override public boolean onGroupClick(ExpandableListView expandableListView, View view, final int i, long l) { DiscogsSearchResult result = (DiscogsSearchResult) mAdapter.getGroup(i); if (result.type.equals("release")) { onItemSelected(result.id); } else { //this is a group item, fetch it's content and add it dynamically to the list if collapsed and first click, else let the listview do it's magic if (mList.isGroupExpanded(i) || mAdapter.getChildrenCount(i) != 0) return false; mCallbacks.setRefreshVisible(true); if (result.type.equals("artist")) { mDiscogs.getArtistReleases(result.id, 1, new Discogs.DiscogsDataWaiter<List<DiscogsSearchRelease>>() { @Override public void onResult(boolean success, List<DiscogsSearchRelease> data) { if (success) { mAdapter.addChildren(i, data); mList.expandGroup(i); } mCallbacks.setRefreshVisible(false); } }); } else if (result.type.equals("label")) { mDiscogs.getLabelReleases(result.id, 1, new Discogs.DiscogsDataWaiter<List<DiscogsSearchRelease>>() { @Override public void onResult(boolean success, List<DiscogsSearchRelease> data) { if (success) { mAdapter.addChildren(i, data); mList.expandGroup(i); } mCallbacks.setRefreshVisible(false); } }); } else if (result.type.equals("master")) { mDiscogs.getMasterReleases(result.id, 1, new Discogs.DiscogsDataWaiter<List<DiscogsSearchRelease>>() { @Override public void onResult(boolean success, List<DiscogsSearchRelease> data) { if (success) { mAdapter.addChildren(i, data); mList.expandGroup(i); } mCallbacks.setRefreshVisible(false); } }); } } //I handled it return true; } } }