Develop Reference

Setting values to multiple child nodes Firebase

I am trying to set values to multiple child nodes in Firebase but when I try to do this android studio highlights the second child as an error. Is there any way of doing this without using a hashmap?
mDatabaseLike.child("ProjectName").setValue(uploadCurrent.getName()).child("Votes/").setValue(mCountLikes);
I want my firebase to be stored as:
CountLikes:{
ProjectName: "abcd"
Votes: "78"
}

Your only other alternative to using a Map is to use a Java object whose members have the values that you want to add. It will go something like this:
class YourObject {
public String ProjectName;
public int Votes;
}
YourObject o = new YourObject();
o.ProjectName = "abcd";
o.Votes = 78;
mDatabaseLike.setValue(o);

Doug's answer is perfectly fine when you want to populate a node with data from a POJO class, in this case with your ProjectName and Votes, but as Frank's comment says, if you had old data at that node before placing the new one, it will be overwrited/deleted from that node.
For example, if you had this at your node
CountLikes:{
ProjectName: "MyAwesomeProject"
Votes: "100"
comments: 20 --> New data that you could add or have
flags: 0 --> New data that you could add or have
favorites: 30 --> New data that you could add or have
}
before doing this
YourObject o = new YourObject();
o.ProjectName = "abcd";
o.Votes = 78;
mDatabaseLike.setValue(o);
All that old data you had at that node will be replaced with this
CountLikes:{
ProjectName: "abcd"
Votes: "78"
}
If you only need to update/change your data at that particular node, I would suggest doing it with the HashMap, because it will just update the values inside that node and not recreate them again and replace/delete them if you already had data there.
Continuing Doug's answer
class YourObject {
public String ProjectName;
public int Votes;
}
String projectName = "abcd";
int votes = 78;
Map<String,Object> mapData = new HashMap<>();
mapData.put("ProjectName",projectName);
mapData.put("Votes",votes);
mDatabaseLike.updateChildren(mapData).addOnCompleteListener(new OnCompleteListener<Void>(){
#Override
public void onComplete(#NonNull Task<Void> task){
//Data pushed succefully, update UI or do something else.
}
});
Doing this will prevent recreating the whole object and just replacing that data inside your node, I know you requested without a HashMap, but I just post why it's a good choice doing it this way.

Get a string list of values from a generic object

So I have an Object that comes in that can be any of 100 different specific objects, with different elements inside it, from other objects, lists, sequences, primitives etc.
I want to strip the values in a depth first fashion to make a string of simple values with a delimiter between them. I have mapped the fields and stored them elsewhere using recursion/reflection that only happens once a new Object type comes in for the first time.
An example of how I'm storing the data in the database for a few simple example objects:
Object A layout table: Timestamp = 12345 Fields = Length|Width|Depth
Object B layout table: Timestamp = 12345 Fields = Height|Weight|Name
Object A layout table: Timestamp = 12350 Fields = Length|Width|Depth|Label
Object A sample: Timestamp = 12348 Values = 5|7|2
Object A sample: Timestamp = 12349 Values = 4|3|1
Object B sample: Timestamp = 12346 Values = 75|185|Steve Irwin
Object A sample: Timestamp = 12352 Values = 7|2|8|HelloWorld
Below is my current solution. I'm seeking improvements or alternatives to the design to accomplish the goal stated above.
Currently I get the object in and translate it to JSON using gson.toJson(); From that, I cycle through the JSON to get values using the code below. Issue is, this code is very CPU intensive on the low end CPU I am developing for due to the fact that there are many samples coming in per second. Overall purpose of the application is a data recorder that records real time samples into a SQLite database. I have also attempted to store the unmodified JSON into a SQLite BLOB column, but this is terribly inefficient with regards to DB size. Is there a better/more efficient method for getting values out of an object?
I don't have an issue storing the field mapping since it only needs to be done once, but the value stripping needs to be done for every sample. I know you can do it via reflection as well, but that is also processing heavy. Anyone have a better method?
public static List<String> stripValuesFromJson(JsonElement json)
{
// Static array list that will have the values added to it. This will
// be the return object
List<String> dataList = new ArrayList<String>();
// Iterate through the JSONElement and start parsing out values
for (Entry<String, JsonElement> entry : ((JsonObject) json).entrySet())
{
// Call the recursive processor that will parse out items based on their individual type: primitive, array, seq etc
dataList.addAll(dataParser(entry.getValue()));
}
return dataList;
}
/**
* The actual data processor that parses out individual values and deals with every possible type of data that can come in.
*
* #param json - The json object being recursed through
* #return - return the list of values
*/
public static List<String> dataParser(JsonElement json)
{
List<String> dataList = new ArrayList<String>();
// Deal with primitives
if (json instanceof JsonPrimitive)
{
// Deal with items that come up as true/false.
if (json.getAsString().equals("false"))
{
dataList.add("0");
} else if (json.getAsString().equals("true"))
{
dataList.add("1");
} else
{
dataList.add(json.getAsString());
}
// Send through recursion to get the primitives or objects out of this object
} else if (json instanceof JsonObject)
{
dataList.addAll(stripValuesFromJson(json));
} else if (json instanceof JsonArray)
{
// Send through recursion for each element in this array/sequence
for (JsonElement a : (JsonArray) json)
{
dataList.addAll(dataParser(a));
}
} else if (json instanceof JsonNull)
{
dataList.add(null);
} else
{
errorLog.error("Unknown JSON type: " + json.getClass());
}
return dataList;
}

One thing you could try out is writing your own JSON parser which simply emits values. I have more experience in JavaCC so I'd take one of existing JSON grammars and modify it so that it only outputs values. This should not be too complicated.
Take for example the booleanValue production from the mentioned grammar:
Boolean booleanValue(): {
Boolean b;
}{
(
(
<TRUE>
{ b = Boolean.TRUE; }
) | (
<FALSE>
{ b = Boolean.FALSE; }
)
)
{ return b; }
}
Basically you will need to replace returning the boolean value with appending "1" or "0" to the target list.
ANTLR is another option.

How to get the distinct element from mediastore by java

I am trying to get the file names of all the audio files but I am getting same file names for multiple songs
1.I cannot use DISTINCT key word as I am getting the file names from DATA .
2.I am using the Mediastore.Files So the select it takes MEDIA_TYPE so this way is also not possible .
3 .I want to get the Parent value as distinct not the repeating value .
So the only way is by doing in java .I followed the method given here but I am not able to set
Here is a piece of my code
if (audioCursor.moveToFirst()) {
do {
int filetitle = audioCursor.getColumnIndexOrThrow(MediaStore.Files.FileColumns.TITLE);
int file_id = audioCursor.getColumnIndexOrThrow(MediaStore.Files.FileColumns._ID);
int fileparent = audioCursor.getColumnIndexOrThrow(MediaStore.Files.FileColumns.PARENT);
int filedata = audioCursor.getColumnIndexOrThrow(MediaStore.Files.FileColumns.DATA);
Mediafileinfo info = new Mediafileinfo();
info.setData(new File(new File(audioCursor.getString(filedata)).getParent()).getName());
info.setTitle(audioCursor.getString(filetitle));
info.set_id(audioCursor.getString(file_id));
info.setParent(audioCursor.getString(fileparent));
audioList.add(info);
} while (audioCursor.moveToNext());
}
How I can get the non repeating elements?? For more info mediastore.file
I am adding the data in Mediafileinfo class which contain getter and setter.

I want to get the Parent value as distinct not the repeating value .
Alright, you could use a HashSet<String> to maintain a list of seen MediaStore.Files.FileColumns.PARENT values.
Not sure what was wrong with the SQL approach, though.
HashSet<String> seenParents = new HashSet<String>();
if (audioCursor.moveToFirst()) {
final int fileparent = audioCursor.getColumnIndexOrThrow(MediaStore.Files.FileColumns.PARENT);
do {
String parent = audioCursor.getString(fileparent);
Mediafileinfo info = new Mediafileinfo();
// bla...
info.setParent(parent);
if (!seenParents.contains(parent)) { // prevents dups
seenParents.add(parent);
audioList.add(info);
}
// end loop

JHDF5 - How to avoid dataset being overwritten

I am using JHDF5 to log a collection of values to a hdf5 file. I am currently using two ArrayLists to do this, one with the values and one with the names of the values.
ArrayList<String> valueList = new ArrayList<String>();
ArrayList<String> nameList = new ArrayList<String>();
valueList.add("Value1");
valueList.add("Value2");
nameList.add("Name1");
nameList.add("Name2");
IHDF5Writer writer = HDF5Factory.configure("My_Log").keepDataSetsIfTheyExist().writer();
HDF5CompoundType<List<?>> type = writer.compound().getInferredType("", nameList, valueList);
writer.compound().write("log1", type, valueList);
writer.close();
This will log the values in the correct way to the file My_Log and in the dataset "log1". However, this example always overwrites the previous log of the values in the dataset "log1". I want to be able to log to the same dataset everytime, adding the latest log to the next line/index of the dataset. For example, if I were to change the value of "Name2" to "Value3" and log the values, and then change "Name1" to "Value4" and "Name2" to "Value5" and log the values, the dataset should look like this:
I thought the keepDataSetsIfTheyExist() option to would prevent the dataset to be overwritten, but apparently it doesn't work that way.
Something similar to what I want can be achieved in some cases with writer.compound().writeArrayBlock(), and specify by what index the array block shall be written. However, this solution doesn't seem to be compatible with my current code, where I have to use lists for handling my data.
Is there some option to achieve this that I have overlooked, or can't this be done with JHDF5?

I don't think that will work. It is not quite clear to me, but I believe the getInferredType() you are using is creating a data set with 2 name -> value entries. So it is effectively creating an object inside the hdf5. The best solution I could come up with was to read the previous values add them to the valueList before outputting:
ArrayList<String> valueList = new ArrayList<>();
valueList.add("Value1");
valueList.add("Value2");
try (IHDF5Reader reader = HDF5Factory.configure("My_Log.h5").reader()) {
String[] previous = reader.string().readArray("log1");
for (int i = 0; i < previous.length; i++) {
valueList.add(i, previous[i]);
}
} catch (HDF5FileNotFoundException ex) {
// Nothing to do here.
}
MDArray<String> values = new MDArray<>(String.class, new long[]{valueList.size()});
for (int i = 0; i < valueList.size(); i++) {
values.set(valueList.get(i), i);
}
try (IHDF5Writer writer = HDF5Factory.configure("My_Log.h5").writer()) {
writer.string().writeMDArray("log1", values);
}
If you call this code a second time with "Value3" and "Value4" instead, you will get 4 values. This sort of solution might become unpleasant if you start to have hierarchies of datasets however.

To solve your issue, you need to define the dataset log1 as extendible so that it can store an unknown number of log entries (that are generated over time) and write these using a point or hyperslab selection (otherwise, the dataset will be overwritten).
If you are not bound to a specific technology to handle HDF5 files, you may wish to give a look at HDFql which is an high-level language to manage HDF5 files easily. A possible solution for your use-case using HDFql (in Java) is:
public class Example
{
public Class Log
{
String name1;
String name2;
}
public boolean doSomething(Log log)
{
log.name1 = "Value1";
log.name2 = "Value2";
return true;
}
public static void main(String args[])
{
// declare variables
Log log = new Log();
int variableNumber;
// create an HDF5 file named 'My_Log.h5' and use (i.e. open) it
HDFql.execute("CREATE AND USE FILE My_Log.h5");
// create an extendible HDF5 dataset named 'log1' of data type compound
HDFql.execute("CREATE DATASET log1 AS COMPOUND(name1 AS VARCHAR, name2 AS VARCHAR)(0 TO UNLIMITED)");
// register variable 'log' for subsequent usage (by HDFql)
variableNumber = HDFql.variableRegister(log);
// call function 'doSomething' that does something and populates variable 'log' with an entry
while(doSomething(log))
{
// alter (i.e. extend) dataset 'log1' to +1 (i.e. add a new row)
HDFql.execute("ALTER DIMENSION log1 TO +1");
// insert (i.e. write) data stored in variable 'log' into dataset 'log1' using a point selection
HDFql.execute("INSERT INTO log1(-1) VALUES FROM MEMORY " + variableNumber);
}
}
}

Trying to compare a HashSet element with an element in a List

I have a HashSet that I created and this is what it contains. It will contain more later on, this is pasted from standard out when I did a toString on it. Just to show the contents.
foo.toString(): Abstractfoo [id=2, serial=1d21d, value=1.25, date=2012-09-02 12:00:00.0]
INFO [STDOUT] price.toString(): Abstractfoo [id=1, serial=1d24d, value=1.30, date=2012-09-19 12:00:00.0]
I have a List that I also have and I need to compare the two. One of the elements in List is:
Bar.toString(): Bar [id=1d21d, name=Dell, description=Laptop, ownerId=null]
Here is what I am trying to do...
Bar contains all of the elements I want foo to have. There will only be one unique serial. I would like my program to see if an element in the list that is in HashSet contains the id for bar. So serial == id.
Here is what I've been trying to do
Removed code and added clearer code below
I've verified the data is getting entered into the HashSet and List correctly by viewing it through the debugger.
foo is being pulled from a database through hibernate, and bar is coming from a different source. If there is an element in bar I need to add it to a list and I'm passing it back to my UI where I'll enter some additional data and then commit it to the database.
Let me know if this makes sense and if I can provide anymore information.
Thanks
EDIT: Here is the class
#RequestMapping(value = "/system", method = RequestMethod.GET)
public #ResponseBody
List<AbstractSystem> SystemList() {
// Retrieve system list from database
HashSet<AbstractSystem> systemData = new HashSet<AbstractSystem>(
systemService.getSystemData());
// Retrieve system info from cloud API
List<SystemName> systemName= null;
try {
systemName = cloudClass.getImages();
} catch (Exception e) {
LOG.warn("Unable to get status", e);
}
// Tried this but, iter2 only has two items and iter has many more.
// In production it will be the other way around, but I need to not
// Have to worry about that
Iterator<SystemName> iter = systemName.iterator();
Iterator<AbstractSystem> iter2 = systemData .iterator();
while(iter.hasNext()){
Image temp = iter.next();
while(iter2.hasNext()){
AbstractPricing temp2 = iter2.next();
System.out.println("temp2.getSerial(): " + temp2.getSerial());
System.out.println("temp.getId(): " + temp.getId());
if(temp2.getSerial().equals(temp.getId())){
System.out.println("This will be slow...");
}
}
}
return systemData;
}

If N is the number of items in systemName and M is the number of items in systemData, then you've effectively built an O(N*M) method.
If you instead represent your systemData as a HashMap of AbstractSystem by AbstractSystem.getSerial() values, then you just loop through the systemName collection and lookup by systemName.getId(). This becomes more like O(N+M).
(You might want to avoid variables like iter, iter2, temp2, etc., since those make the code harder to read.)
EDIT - here's what I mean:
// Retrieve system list from database
HashMap<Integer, AbstractSystem> systemDataMap = new HashMap<AbstractSystem>(
systemService.getSystemDataMap());
// Retrieve system info from cloud API
List<SystemName> systemNames = cloudClass.getImages();
for (SystemName systemName : systemNames) {
if (systemDataMap.containsKey(systemName.getId()) {
System.out.println("This will be slow...");
}
}
I used Integer because I can't tell from your code what the type of AbstractSystem.getSerial() or SystemName.getId() are. This assumes that you store the system data as a Map elsewhere. If not, you could construct the map yourself here.