Java tutorial
/* 50AH-code ========= 50 Android Hacks (http://manning.com/sessa/) book source code Copyright (c) 2012 Manning Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ /******************************************************************************* * Copyright (c) 2012 Manning * See the file license.txt for copying permission. ******************************************************************************/ package com.manning.androidhacks.hack041; import java.sql.SQLException; import java.text.SimpleDateFormat; import java.util.ArrayList; import java.util.Collections; import java.util.Date; import java.util.List; import java.util.concurrent.Callable; import android.app.Activity; import android.app.AlertDialog; import android.app.ProgressDialog; import android.content.DialogInterface; import android.os.AsyncTask; import android.os.Bundle; import android.view.LayoutInflater; import android.view.View; import android.widget.EditText; import android.widget.TextView; import com.j256.ormlite.dao.Dao; import com.j256.ormlite.stmt.PreparedQuery; import com.manning.androidhacks.hack041.data.Article; import com.manning.androidhacks.hack041.data.ArticleAuthor; import com.manning.androidhacks.hack041.data.Author; import com.manning.androidhacks.hack041.data.Comment; import com.manning.androidhacks.hack041.data.DatabaseHelper; /** * An Activity for showing more types of queries using OrmLite. */ public class ArticleActivity extends Activity { public static String ARTICLE_ID = "ARTICLE_ID"; private LoadArticleTask task; private AddCommentTask commentTask; private ProgressDialog dialog; private int articleId; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.article); articleId = getIntent().getIntExtra(ARTICLE_ID, -1); if (articleId == -1) throw new RuntimeException("Extra must be passed in!"); dialog = ProgressDialog.show(this, null, "Loading Articles", true, false); /* * Kick off a task (if needed) to load the data for this activity. Note: We * must be mindful of screen orientation changes here. */ task = (LoadArticleTask) getLastNonConfigurationInstance(); if (task == null) { task = new LoadArticleTask(this, articleId); task.execute(); } else { task.attach(this); } } @Override public Object onRetainNonConfigurationInstance() { if (task != null) task.detach(); if (commentTask != null) commentTask.detach(); // No need to retain this AsyncTask. Upon // orientation change, the new transaction to // read data will be serialized and see any // pending update. return task; } public void handleDataLoaded(ArticleModel model) { dialog.dismiss(); task.detach(); task = null; // Fill out the views for this Activity. TextView title = (TextView) findViewById(R.id.article_title); title.setText(model.article.getTitle()); TextView subTitle = (TextView) findViewById(R.id.article_sub_title); subTitle.setText(model.getSubTitleText()); TextView articleText = (TextView) findViewById(R.id.article_text); articleText.setText(model.article.getText()); findViewById(R.id.divider).setVisibility(View.VISIBLE); updateCommentCount(model.commentCount); // Setup click events. findViewById(R.id.addComment).setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { addCommentPrompt(); } }); } private void updateCommentCount(long count) { TextView commentCount = (TextView) findViewById(R.id.comment_count); commentCount.setText(String.format("Comments: %d", count)); } private void addCommentPrompt() { View body = LayoutInflater.from(this).inflate(R.layout.comment_dialog, null); final EditText nameEditText = (EditText) body.findViewById(R.id.name); final EditText commentEditText = (EditText) body.findViewById(R.id.comment); new AlertDialog.Builder(this).setTitle("Add Comment").setView(body) .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialogInterface, int i) { String name = nameEditText.getText().toString().trim(); String comments = commentEditText.getText().toString().trim(); if (!name.equals("") && !comments.equals("")) { insertComment(name, comments); } } }).setNegativeButton(android.R.string.cancel, new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialogInterface, int i) { // do nothing } }).show(); } private void insertComment(final String name, final String comments) { commentTask = new AddCommentTask(this, articleId, name, comments); commentTask.execute(); } private static class ArticleModel { private Article article; private List<Author> authorList = new ArrayList<Author>(); private long commentCount; SimpleDateFormat formatter = new SimpleDateFormat(" 'on' M/d/yyyy h:mm a"); private ArticleModel(Article article) { if (article == null) throw new IllegalArgumentException("Passed in article must be non-null!"); this.article = article; } public String getSubTitleText() { Collections.sort(authorList); StringBuilder sb = new StringBuilder("Created by"); if (authorList.size() == 0) sb.append(" unknown"); else { sb.append(" ").append(authorList.get(0).getName()); if (authorList.size() > 1) { for (int i = 1; i < authorList.size(); i++) sb.append(", ").append(authorList.get(i).getName()); } } sb.append(formatter.format(article.getPublishedDate())); return sb.toString(); } } /** * Task to load the needed items out of the database. This will demo some more * ways to query a database with OrmLite. */ private static class LoadArticleTask extends AsyncTask<Void, Void, ArticleModel> { private boolean done; private ArticleModel payload; private ArticleActivity host; private int articleId; private LoadArticleTask(ArticleActivity host, int id) { this.host = host; this.articleId = id; } @Override protected ArticleModel doInBackground(Void... voids) { final DatabaseHelper helper = DatabaseHelper.getInstance(host); // We will perform multiple queries on the database, so we will use // a transaction, which will help performance. return helper.callInTransaction(new Callable<ArticleModel>() { @Override public ArticleModel call() throws SQLException { // First, we use queryForId() to get the Article // itself. Dao<Article, Integer> articleDao = helper.getArticleDao(); Article article = articleDao.queryForId(articleId); // Start to construct our return object, which will // hold all data needed to populate the Activity. ArticleModel model = new ArticleModel(article); // Then, we get all the Authors for this Article. // This will demo the QueryBuilder class. Dao<ArticleAuthor, Void> authorDao = helper.getArticleAuthorDao(); PreparedQuery<ArticleAuthor> query = authorDao.queryBuilder().where() .eq(ArticleAuthor.ARTICLE_ID_COLUMN, articleId).prepare(); // Now, run the query List<ArticleAuthor> results = authorDao.query(query); for (ArticleAuthor item : results) { Author author = item.getAuthor(); model.authorList.add(author); } // Finally, get a count of the comments. We will use // the QueryBuilder class again. Dao<Comment, Integer> commentDao = helper.getCommentDao(); model.commentCount = countCommentsForId(commentDao, articleId); return model; } }); } @Override protected void onPostExecute(ArticleModel articleModel) { done = true; payload = articleModel; host.handleDataLoaded(articleModel); } public void detach() { host = null; } public void attach(ArticleActivity newActivity) { host = newActivity; if (done) host.handleDataLoaded(payload); } } private static class AddCommentTask extends AsyncTask<Void, Void, Long> { private int articleId; private String name, comments; private ArticleActivity host; private DatabaseHelper helper; private AddCommentTask(ArticleActivity host, int articleId, String name, String comments) { this.host = host; this.articleId = articleId; this.comments = comments; this.name = name; helper = DatabaseHelper.getInstance(host); } @Override protected Long doInBackground(Void... voids) { // Note: The ORM only needs the ID set for foreign objects for it to // properly set the column value. Article article = new Article(); article.setId(articleId); final Comment comment = new Comment(article, new Date(), comments, name); // Perform the insert. Then, get a new count. return helper.callInTransaction(new Callable<Long>() { @Override public Long call() throws SQLException { Dao<Comment, Integer> commentDao = helper.getCommentDao(); commentDao.create(comment); return countCommentsForId(commentDao, articleId); } }); } @Override protected void onPostExecute(Long count) { if (host != null) host.updateCommentCount(count); } public void detach() { host = null; } } /** * This function is used in multiple places, so we will define it once, as a * static method. * * @param commentDao * A Dao object for use when querying. * @param articleId * The ID of the article. * @return A count of the comments associated with the given ID. * @throws SQLException */ private static long countCommentsForId(Dao<Comment, Integer> commentDao, int articleId) throws SQLException { PreparedQuery<Comment> countQuery = commentDao.queryBuilder().setCountOf(true).where() .eq(Comment.ARTICLE_COLUMN, articleId).prepare(); return commentDao.countOf(countQuery); } }