Java tutorial
/* * Copyright 2012 Google Inc. * * 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.google.android.apps.iosched.ui; import android.app.Activity; import android.content.Context; import android.content.Intent; import android.database.Cursor; import android.graphics.Color; import android.net.Uri; import android.os.Bundle; import android.provider.BaseColumns; import android.support.v4.app.ListFragment; import android.support.v4.app.LoaderManager; import android.support.v4.content.CursorLoader; import android.support.v4.content.Loader; import android.support.v4.widget.CursorAdapter; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.ListView; import android.widget.TextView; import com.google.android.apps.iosched.R; import com.google.android.apps.iosched.provider.ScheduleContract; import com.google.android.apps.iosched.util.UIUtils; import static com.google.android.apps.iosched.util.LogUtils.makeLogTag; /** * A {@link ListFragment} showing a list of sandbox comapnies. */ public class SandboxFragment extends ListFragment implements LoaderManager.LoaderCallbacks<Cursor> { private static final String TAG = makeLogTag(SandboxFragment.class); private static final String STATE_SELECTED_ID = "selectedId"; private Uri mSandboxUri; private CursorAdapter mAdapter; private String mSelectedCompanyId; public interface Callbacks { /** Return true to select (activate) the company in the list, false otherwise. */ public boolean onCompanySelected(String companyId); } private static Callbacks sDummyCallbacks = new Callbacks() { @Override public boolean onCompanySelected(String companyId) { return true; } }; private Callbacks mCallbacks = sDummyCallbacks; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); if (savedInstanceState != null) { mSelectedCompanyId = savedInstanceState.getString(STATE_SELECTED_ID); } } @Override public void onActivityCreated(Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); // As of support library r12, calling initLoader for a fragment in a FragmentPagerAdapter // in the fragment's onCreate may cause the same LoaderManager to be dealt to multiple // fragments because their mIndex is -1 (haven't been added to the activity yet). Thus, // we call reloadFromArguments (which calls restartLoader/initLoader) in onActivityCreated. reloadFromArguments(getArguments()); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View rootView = inflater.inflate(R.layout.fragment_list_with_empty_container_inset, container, false); TextView emptyView = new TextView(getActivity(), null, R.attr.emptyText); emptyView.setText(R.string.empty_sandbox); ((ViewGroup) rootView.findViewById(android.R.id.empty)).addView(emptyView); return rootView; } void reloadFromArguments(Bundle arguments) { // Teardown from previous arguments setListAdapter(null); // Load new arguments final Intent intent = BaseActivity.fragmentArgumentsToIntent(arguments); mSandboxUri = intent.getData(); if (mSandboxUri == null) { mSandboxUri = ScheduleContract.Sandbox.CONTENT_URI; } final int sandboxQueryToken; mAdapter = new SandboxAdapter(getActivity()); sandboxQueryToken = SandboxQuery._TOKEN; setListAdapter(mAdapter); // Start background query to load sandbox getLoaderManager().initLoader(sandboxQueryToken, null, this); } public void setSelectedCompanyId(String id) { mSelectedCompanyId = id; if (mAdapter != null) { mAdapter.notifyDataSetChanged(); } } @Override public void onViewCreated(View view, Bundle savedInstanceState) { super.onViewCreated(view, savedInstanceState); view.setBackgroundColor(Color.WHITE); final ListView listView = getListView(); listView.setSelector(android.R.color.transparent); listView.setCacheColorHint(Color.WHITE); } @Override public void onAttach(Activity activity) { super.onAttach(activity); if (!(activity instanceof Callbacks)) { throw new ClassCastException("Activity must implement fragment's callbacks."); } mCallbacks = (Callbacks) activity; } @Override public void onDetach() { super.onDetach(); mCallbacks = sDummyCallbacks; } @Override public void onSaveInstanceState(Bundle outState) { super.onSaveInstanceState(outState); if (mSelectedCompanyId != null) { outState.putString(STATE_SELECTED_ID, mSelectedCompanyId); } } /** {@inheritDoc} */ @Override public void onListItemClick(ListView l, View v, int position, long id) { final Cursor cursor = (Cursor) mAdapter.getItem(position); String companyId = cursor.getString(SandboxQuery.COMPANY_ID); if (mCallbacks.onCompanySelected(companyId)) { mSelectedCompanyId = companyId; mAdapter.notifyDataSetChanged(); } } /** * {@link CursorAdapter} that renders a {@link com.google.android.apps.iosched.ui.SandboxFragment.SandboxQuery}. */ private class SandboxAdapter extends CursorAdapter { public SandboxAdapter(Context context) { super(context, null, 0); } /** {@inheritDoc} */ @Override public View newView(Context context, Cursor cursor, ViewGroup parent) { return getActivity().getLayoutInflater().inflate(R.layout.list_item_sandbox, parent, false); } /** {@inheritDoc} */ @Override public void bindView(View view, Context context, Cursor cursor) { UIUtils.setActivatedCompat(view, cursor.getString(SandboxQuery.COMPANY_ID).equals(mSelectedCompanyId)); ((TextView) view.findViewById(R.id.company_name)).setText(cursor.getString(SandboxQuery.NAME)); } } /** * {@link com.google.android.apps.iosched.provider.ScheduleContract.Sandbox} * query parameters. */ private interface SandboxQuery { int _TOKEN = 0x1; String[] PROJECTION = { BaseColumns._ID, ScheduleContract.Sandbox.COMPANY_ID, ScheduleContract.Sandbox.COMPANY_NAME, }; int _ID = 0; int COMPANY_ID = 1; int NAME = 2; } @Override public Loader<Cursor> onCreateLoader(int id, Bundle data) { return new CursorLoader(getActivity(), mSandboxUri, SandboxQuery.PROJECTION, null, null, ScheduleContract.Sandbox.DEFAULT_SORT); } @Override public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) { if (getActivity() == null) { return; } int token = loader.getId(); if (token == SandboxQuery._TOKEN) { mAdapter.changeCursor(cursor); } else { cursor.close(); } } @Override public void onLoaderReset(Loader<Cursor> cursor) { } }