Develop Reference

Annotation Processor : initialize a field

I am writing an annotation processor in android which generates a java file. I am using JavaPoet library for that.
The purpose of generated file:
It should have a list of names of the classes with a particular annotation that my processor supports and provide a public method to get that list.
Now, I've generated the file:
private final List<String> names;
GeneratedFile(ArrayList<String> names) {
this.names = names;
}
public List<String> getNames() {
return names;
}
Now, the problem is: How do I initialize the names field from the processor? The Javapoet api provides an initializer for the field but that only takes a string.
In my processor, I've the list of classes that have my supported annotation. I want to populate this field with that list.

As you already know, JavaPoet offers only a string to specify field initialization. To accomplish your task you have to (I will show you some code that is not specific to your problem, but it can be a good example to show you how to do it):
Get from your annotation processor the list of classes with your annotation (the code is copied from a my library):
#Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
model = new PrefsModel();
parseBindType(roundEnv);
// Put all #BindSharedPreferences elements in beanElements
for (Element item : roundEnv.getElementsAnnotatedWith(BindSharedPreferences.class)) {
AssertKripton.assertTrueOrInvalidKindForAnnotationException(item.getKind() == ElementKind.CLASS, item, BindSharedPreferences.class);
// store type name somewhere
}
return true;
}
Use this set of TypeName to generate the initial value for you field:
...
Builder sp = FieldSpec.builder(ArrayTypeName.of(String.class), "COLUMNS", Modifier.STATIC, Modifier.PRIVATE,
Modifier.FINAL);
String s = "";
StringBuilder buffer = new StringBuilder();
for (SQLProperty property : entity.getCollection()) {
buffer.append(s + "COLUMN_" +
columnNameToUpperCaseConverter.convert(property.getName()));
s = ", ";
}
classBuilder.addField(sp.addJavadoc("Columns array\n").initializer("{" +
buffer.toString() + "}").build());
...
You will find my library on github. In particular, you have to read the class com.abubusoft.kripton.processor.sqlite.BindTableGenerator.
Hope this information can be still useful.

Android - XML or SQLite for static data

I am making Android app for practicing driving licence theory tests. I will have about 3000 questions. Question object would have several atributes (text, category, subcategory, answers, group). I will create them and put in app, so data won't ever change. When user chooses category, app would go througt data, look which question meets requirements (that user selected) and put it in list for displaying. What should I use to store data/questions, XML or SQLite? Thanks in advance.
Edit:
I forgot to mentiont that app won't use internet connection. Also, I planned to make simple java app for entering data. I would copy text from government's website (I don't have access to their database and I have to create mine), so I thought to just put question's image url to java program and it would download it and name it automaticaly. Also, when entering new question's text it would tell me if that question already exist before I enter other data. That would save me time, I wouldn't have to save every picture and name it my self. That is what I thought if using XML. Can I do this for JSON or SQLite?

If you do not have to perform complex queries, I would recommend to store your datas in json since very well integrated in android apps using a lib such as GSON or Jackson.
If you don't want to rebuild your app / redeploy on every question changes. You can imagine to have a small webserver (apache, nginx, tomcat) that serves the json file that you will request on loading of the app. So that you will download the questions when your app is online or use the cached one.
XML is a verbose format for such an usage, and does not bring much functions....
To respond to your last question, you can organise your code like that :
/**
* SOF POST http://stackoverflow.com/posts/37078005
* #author Jean-Emmanuel
* #company RIZZE
*/
public class SOF_37078005 {
#Test
public void test() {
QuestionsBean questions = new QuestionsBean();
//fill you questions
QuestionBean b=buildQuestionExemple();
questions.add(b); // success
questions.add(b); //skipped
System.out.println(questions.toJson()); //toJson
}
private QuestionBean buildQuestionExemple() {
QuestionBean b= new QuestionBean();
b.title="What is the size of your boat?";
b.pictures.add("/res/images/boatSize.jpg");
b.order= 1;
return b;
}
public class QuestionsBean{
private List<QuestionBean> list = new ArrayList<QuestionBean>();
public QuestionsBean add(QuestionBean b ){
if(b!=null && b.title!=null){
for(QuestionBean i : list){
if(i.title.compareToIgnoreCase(b.title)==0){
System.out.println("Question "+b.title+" already exists - skipped & not added");
return this;
}
}
System.out.println("Question "+b.title+" added");
list.add(b);
}
else{
System.out.println("Question was null / not added");
}
return this;
}
public String toJson() {
ObjectMapper m = new ObjectMapper();
m.configure(Feature.ALLOW_SINGLE_QUOTES, true);
String j = null;
try {
j= m.writeValueAsString(list);
} catch (JsonProcessingException e) {
e.printStackTrace();
System.out.println("JSON Format error:"+ e.getMessage());
}
return j;
}
}
public class QuestionBean{
private int order;
private String title;
private List<String> pictures= new ArrayList<String>(); //path to picture
private List<String> responseChoice = new ArrayList<String>(); //list of possible choices
public int getOrder() {
return order;
}
public void setOrder(int order) {
this.order = order;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public List<String> getPictures() {
return pictures;
}
public void setPictures(List<String> pictures) {
this.pictures = pictures;
}
public List<String> getResponseChoice() {
return responseChoice;
}
public void setResponseChoice(List<String> responseChoice) {
this.responseChoice = responseChoice;
}
}
}
CONSOLE OUTPUT
Question What is the size of your boat? added
Question What is the size of your boat? already exists - skipped & not added
[{"order":1,"title":"What is the size of your boat?","pictures":["/res/images/boatSize.jpg"],"responseChoice":[]}]
GIST :
provides you the complete working code I've made for you
https://gist.github.com/jeorfevre/5d8cbf352784042c7a7b4975fc321466
To conclude, what is a good practice to work with JSON is :
1) create a bean in order to build your json (see my example here)
2) build your json and store it in a file for example
3) Using android load your json from the file to the bean (you have it in andrdoid)
4) use the bean to build your form...etc (and not the json text file) :D

I would recommend a database (SQLite) as it provides superior filtering functionality over xml.

Create the db using DB Browser for SQLite
And then use the library SQLiteAssetHelper in the link-
https://github.com/jgilfelt/android-sqlite-asset-helper
Tutorial on how to use -
http://www.javahelps.com/2015/04/import-and-use-external-database-in.html

You can use Paper https://github.com/pilgr/Paper its a fast NoSQL data storage for Android.

SQLite is the best for your system. because you will have to maintain (text, category, subcategory, answers, group) etc. So if you create db and create table for them. That will be easy to manage and you can relationship with each other which is not possible to XML.

How to make query using google app engine endpoint for android?

I'm developing an Android project using google app engine endpoints. We tried to insert a new query in an automatically generated endpoint class (I have a Poll.java class and a PollEndpoint.java class) in the server side, but the system doesn't work because a red cross is showed on the AppEngine part of the project. No other error message are shown.
Code insert in PollEndpoint.java class:
#ApiMethod(name = "getLastPoll")
public Long getLastPoll(#Named("date") Date date, #Named("creator") String creator) {
EntityManager mgr = getEntityManager();
Key id = null;
try {
Query query = mgr.createQuery("select keyPoll from Poll where creator
=" + creator + " and creationDate = " + date);
id = (Key)query.getSingleResult();
} finally {
mgr.close();
}
return id.getId();
}
Is it correct to do query in this way?

When you get a red cross on the project but can't see any errors I suggest you look at the errors/warning view (I think that's what its called). You haven't specified your IDE so I'm assuming Eclipse.
Most often it is a problem with your build path.

ORMLite joins queries and Order by

I'm tring to make join in two tables and get all columns in both, I did this:
QueryBuilder<A, Integer> aQb = aDao.queryBuilder();
QueryBuilder<B, Integer> bQb = bDao.queryBuilder();
aQb.join(bQb).prepare();
This equates to:
SELECT 'A'.* FROM A INNER JOIN B WHERE A.id = B.id;
But I want:
SELECT * FROM A INNER JOIN B WHERE A.id = B.id;
Other problem is when taking order by a field of B, like:
aQb.orderBy(B.COLUMN, true);
I get an error saying "no table column B".

When you are using the QueryBuilder, it is expecting to return B objects. They cannot contain all of the fields from A in B. It will not flesh out foreign sub-fields if that is what you mean. That feature has not crossed the lite barrier for ORMLite.
Ordering on join-table is also not supported. You can certainly add the bQb.orderBy(B.COLUMN, true) but I don't think that will do what you want.
You can certainly use raw-queries for this although it is not optimal.

Actually, I managed to do it without writing my whole query as raw query. This way, I didn't need to replace my query builder codes (which is pretty complicated). To achieve that, I followed the following steps:
(Assuming I have two tables, my_table and my_join_table and their daos, I want to order my query on my_table by the column order_column_1 of the my_join_table)
1- Joined two query builders & used QueryBuilder.selectRaw(String... columns) method to include the original table's + the columns I want to use in foreign sort. Example:
QueryBuilder<MyJoinTable, MyJoinPK> myJoinQueryBuilder = myJoinDao.queryBuilder();
QueryBuilder<MyTable, MyPK> myQueryBuilder = myDao.queryBuilder().join(myJoinQueryBuilder).selectRaw("`my_table`.*", "`my_join_table`.`order_column` as `order_column_1`");
2- Included my order by clauses like this:
myQueryBuilder.orderByRaw("`order_column_1` ASC");
3- After setting all the select columns & order by clauses, it's time to prepare the statement:
String statement = myQueryBuilder.prepare().getStatement();
4- Get the table info from the dao:
TableInfo tableInfo = ((BaseDaoImpl) myDao).getTableInfo();
5- Created my custom column-to-object mapper which just ignores the unknown column names. We avoid the mapping error of our custon columns (order_column_1 in this case) by doing this. Example:
RawRowMapper<MyTable> mapper = new UnknownColumnIgnoringGenericRowMapper<>(tableInfo);
6- Query the table for the results:
GenericRawResults<MyTable> results = activityDao.queryRaw(statement, mapper);
7- Finally, convert the generic raw results to list:
List<MyTable> myObjects = new ArrayList<>();
for (MyTable myObject : results) {
myObjects.add(myObject);
}
Here's the custom row mapper I created by modifying (just swallowed the exception) com.j256.ormlite.stmt.RawRowMapperImpl to avoid the unknown column mapping errors. You can copy&paste this into your project:
import com.j256.ormlite.dao.RawRowMapper;
import com.j256.ormlite.field.FieldType;
import com.j256.ormlite.table.TableInfo;
import java.sql.SQLException;
public class UnknownColumnIgnoringGenericRowMapper<T, ID> implements RawRowMapper<T> {
private final TableInfo<T, ID> tableInfo;
public UnknownColumnIgnoringGenericRowMapper(TableInfo<T, ID> tableInfo) {
this.tableInfo = tableInfo;
}
public T mapRow(String[] columnNames, String[] resultColumns) throws SQLException {
// create our object
T rowObj = tableInfo.createObject();
for (int i = 0; i < columnNames.length; i++) {
// sanity check, prolly will never happen but let's be careful out there
if (i >= resultColumns.length) {
continue;
}
try {
// run through and convert each field
FieldType fieldType = tableInfo.getFieldTypeByColumnName(columnNames[i]);
Object fieldObj = fieldType.convertStringToJavaField(resultColumns[i], i);
// assign it to the row object
fieldType.assignField(rowObj, fieldObj, false, null);
} catch (IllegalArgumentException e) {
// log this or do whatever you want
}
}
return rowObj;
}
}
It's pretty hacky & seems like overkill for this operation but I definitely needed it and this method worked well.

Robolectric: Testing with ormlite

I'm trying to test ORMLite DAOs with robolectric, but database behaviour is not the same as when it's used from my android app. My DAOs are working perfectly well on the android application.
Reading about robolectric shadows and debugging code, I encountered ShadowSQLiteOpenHelper (code here).
Does anyone know if this Shadow is enough to test ormlite daos? Or I have to create my own shadow to achieve that? Any clue/tip/suggestion/example here?
Thanks in advance.
Extra info:
Test method:
#Test
public void basicTest() throws SQLException {
assertNotNull(randomStringResource); // Injection of an android resource: OK
assertThat(randomStringResource, equalTo("Event")); // With correct value: OK
assertNotNull(eventDao); // Dao injection: OK
assertThat(eventDao.countOf(), equalTo(0L)); // Table empty: OK
Event e1 = new Event("e1", new Date());
eventDao.create(e1);
assertNotNull(e1.getId()); // ID generated by OrmLite: OK
assertThat(eventDao.countOf(), equalTo(1L)); // Table not empty: OK
assertThat("e1", equalTo(eventDao.queryForId(e1.getId()).getName())); // Query for inserted event: Throws exception
}
Some of the problems encountered running this test:
Errors querying entities with "camelCased" property names: error thrown at last line of test (related problem). Never had a problem like this running the android app.
When I changed one of these properties name (e.g., isEnabled to enabled) in order to avoid the camelCase problem, the previous error persisted... seems like memory database didn't apply the changes that I made on the entity.
Versions used:
Robolectric 1.1
OrmLite 4.41

Sorry for resurrecting your topic but I ran into the same problem.
I'm using OrmLite 4.45 and Robolectric 2.1.
In ShadowSQLiteCursor.java, cacheColumnNames method calls toLowerCase on each column name. So I decided to extend ShadowSQLiteCursor with my own (which doesn't call toLowerCase):
/**
* Simulates an Android Cursor object, by wrapping a JDBC ResultSet.
*/
#Implements(value = SQLiteCursor.class, inheritImplementationMethods = true)
public class ShadowCaseSensitiveSQLiteCursor extends ShadowSQLiteCursor {
private ResultSet resultSet;
public void __constructor__(SQLiteCursorDriver driver, String editTable, SQLiteQuery query) {}
/**
* Stores the column names so they are retrievable after the resultSet has closed
*/
private void cacheColumnNames(ResultSet rs) {
try {
ResultSetMetaData metaData = rs.getMetaData();
int columnCount = metaData.getColumnCount();
columnNameArray = new String[columnCount];
for(int columnIndex = 1; columnIndex <= columnCount; columnIndex++) {
String cName = metaData.getColumnName(columnIndex);
this.columnNames.put(cName, columnIndex - 1);
this.columnNameArray[columnIndex - 1] = cName;
}
} catch(SQLException e) {
throw new RuntimeException("SQL exception in cacheColumnNames", e);
}
}
}
My answer obviously comes too late but may help others!