I am new to both Android and Stack Overflow. I have started developing and Android App and I am wondering two things:
1) Is it possible to parametrize a TextView? Lets say I want to render a text message which states something like: "The user age is 38". Lets suppose that the user age is the result of an algorithm. Using some typical i18n framework I would write in my i18n file something like "The user age is {0}". Then at run time I would populate parameters accordingly. I haven't been able to figure out how to do this or similar approach in Android.
2) Let's suppose I have a complex object with many fields. Eg: PersonModel which has id, name, age, country, favorite video game, whatever. If I want to render all this information into a single layout in one of my activities the only way I have found is getting all needed TextViews by id and then populate them one by one through code.
I was wondering if there is some mapping / binding mechanism in which I can execute something like: render(myPerson, myView) and that automatically through reflection each of the model properties get mapped into each of the TextViews.
If someone has ever worked with SpringMVC, Im looking for something similar to their mechanism to map domain objects / models to views (e.g. spring:forms).
Thanks a lot in advanced for your help. Hope this is useful for somebody else =)
bye!
In answer to #1: You want String.format(). It'll let you do something like:
int age = 38;
String ageMessage = "The user age is %d";
myTextView.setText(String.format(ageMessage, age));
The two you'll use the most are %d for numbers and %s for strings. It uses printf format if you know it, if you don't there's a quicky tutorial in the Formatter docs.
For #2 I think you're doing it the best way there is (grab view hooks and fill them in manually). If you come across anything else I'd love to see it.
Related
I am trying to build an android app that the user can enter a string, and a list emoji related to that string would show up. (Just like Venmo app) For example:
case 1: User enters "pizz", and in the list there would be "🍕", note that the users enter "pizz", not pizza!
case 2: User enters "rabb", and in the list there would be "🐇" and "🐰", note that the users enter "rabb", not rabbit!
What would be a good data structure and algorithm for this problem?
A trie is what your looking for. From Wikipedia
A trie, also called digital tree and sometimes radix tree or prefix tree (as they can be searched by prefixes), is a kind of search tree—an ordered tree data structure ...
A trie is similar to a HashMap<K,V>, you can perform a lookup with keys and get a value. The difference is that you can also search by prefix. Given a prefix, it will find all the key-value pairs in the structure that have that prefix. It's basically the data structure for generating search suggestions.
General Idea:
Trie<String, String> t = new Trie<String, String>();
t.insert("pizza", "🍕");
t.insert("rabbit1", "🐇");
t.insert("rabbit2", "🐰");
// then later...
t.findByPrefix("rabb"); // [🐇,🐰]
Unfortunately, tries are too generic and are not present in any popular data structure libraries (like Java Collections Framework or Google Guava, for example). You'd have to implement one yourself or find an existing implementation and modify it.
I'd recommend:
Learning the theory. Watch this video. There are many more on YouTube that will teach you the basics. You can also search google for "N-way trie" and read notes about it.
Taking this class TrieST and modifying it. It's very similar (or already perfect) for what you need: http://algs4.cs.princeton.edu/52trie/TrieST.java.html see specifically thekeysWithPrefix method.
I want to create a simple search in my app, but cannot find anything on interwebs about it, that's more recent than 2014. There must be a better way. There are startAt and endAt functions but they don't work as expected and are case sensitive. How do you guys solve this problem? How can this functionality still not exist in 2016?
In my case I was able to partly achieve a SQL LIKE in the following way:
databaseReference.orderByChild('_searchLastName')
.startAt(queryText)
.endAt(queryText+"\uf8ff")
The character \uf8ff used in the query is a very high code point in the Unicode range (it is a Private Usage Area [PUA] code). Because it is after most regular characters in Unicode, the query matches all values that start with queryText.
In this way, searching by "Fre" I could get the records having "Fred, Freddy, Frey" as value in _searchLastName property from the database.
Create two String variables
searchInputToLower = inputText.getText().toString().toLowerCase();
searchInputTOUpper = inputText.getText().toString().toUpperCase();
Then in the Query set it to:
DatabaseReference reference = FirebaseDatabase.getInstance().getReference().child("Products");//Your firebase node you want to search inside..
FirebaseRecyclerOptions<Products> options =
new FirebaseRecyclerOptions.Builder<Products>()//the Products is a class that get and set Strings from Firebase Database.
.setQuery(reference.orderByChild("name").startAt(searchInputUpper).endAt(searchInputLower + "\uf8ff"),Products.class)
.build();
the "name" it's the node inside the Products Main Node.
the .startAt(searchInputUpper) & .endAt(searchInputLower + "\uf8ff") to make the search as contains all characters that typed in the inputText.getText() that you get.
finally I got it you can use where clause to get you result like SQL
LIKE keyword like% or %like
syntax :
Firestore.collection(collectionName).orderBy(field).where(field, ">=", keyword.toUpperCase()).where(field, "<=", keyword.toUpperCase() + "\uf8ff").get()
I my case used:
var query = 'text'
databaseReference.orderByChild('search_name')
.startAt(`%${query}%`)
.endAt(query+"\uf8ff")
.once("value")
In this way, searching by "test" I could get the records having "Test 1, Contest, One test" as value in 'search' property from the database.
Firebase is noSQL therefore it does not have searches built in like you'll find in SQL. You can either sort by values/key or you can equalto
https://firebase.google.com/docs/database/android/retrieve-data
You can find examples at the link above. That is the latest documentation for firebase.
If you are looking for SQL like searches. Then take a look at elastic search. But that will increase the complexity since you need a platform to put it on. For that i could recommend Heroku or maybe GoogleCloudServers
Here is a blog post about advanced searches with elastic search
https://firebase.googleblog.com/2014/01/queries-part-2-advanced-searches-with.html
This question might be old but there is a documented way of how to achieve this way, It is simple to implement. Quoted:
To enable full text search of your Cloud Firestore data, use a third-party search service like Algolia. Consider a note-taking app where each note is a document:
Algolia will be part of your firebase functions and will do all the searches you want.
// Update the search index every time a blog post is written.
exports.onNoteCreated = functions.firestore.document('notes/{noteId}').onCreate(event => {
// Get the note document
const note = event.data.data();
// Add an 'objectID' field which Algolia requires
note.objectID = event.params.noteId;
// Write to the algolia index
const index = client.initIndex(ALGOLIA_INDEX_NAME);
return index.saveObject(note);
});
To implement the search, the best way is to use instant search - android
Sample Search Image: GIF
The feature you're looking for is called full-text search and this is something most databases (including Firebase) don't provide out-of-the-box because it requires storing the data in a format that's optimized for text search (vs optimized for filtering) - these are two different problem sets with a different set of trade-offs.
So you would have to use a separate full-text search engine in conjunction with Firebase to be able to do this, especially if you need features like faceting, typo tolerance, merchandizing, etc.
You have a few options for a full-text search engine:
There's Algolia which is easy to get up and running but can get expensive quickly
There's ElasticSearch which has a steep learning curve but uber flexible
There's Typesense which aims to be an open source alternative to Algolia.
I don't know about the certainty of this approach but using the firebase version 10.2.6 on android, i get to do something like this:
firebaseDatabase.getReference("parent")
.orderByChild("childNode")
.startAt("[a-zA-Z0-9]*")
.endAt(searchString)
It seems to work well sometimes
Finally joined SO just to answer this.
For anyone coming here from/for the python firestore.client here's a solution that seems to work for me.
It's based on the accepted answer's concept but via the client rather than db.reference() and mixed with the answer from user12750908.
from firebase_admin import firestore
users = db.collection("users")\
.order_by("last_name")\
.where("last_name", ">=", last_name.upper())\
.where("last_name", "<=", last_name.lower() + "\uf8ff")\
.stream()
It works for the simple test I did, but I'll update my answer if I have issues with it later. And just a reminder, this is similar to
LIKE search%
and not
LIKE %search%.
Edit 1
I didn't see any tags for the question, but the title attribute mentions Android so this may not necessarily answer the question directly, but if you have a python API, this should work. I'm unfortunately not sure if there's an equivalent client/db separation in the Android version like there is in the Firebase Admin for Python. I didn't want to delete the answer since I hadn't seen any answers for firestore client during my search for a similar answer and hope it helps anyone else stumbling around.
Edit 09-03-2020 This works a portion of the time it seems. Most of the time I didn't seem to have an issue, but when I applied it to another project I was getting unexpected results. Long story short you may need to replicate how you save the data you're comparing against. For example, you may need to have a field to save the last_name in all caps and another field to save it in all lowercase, then you change the first where clause to compare last_name_upper and the second to compare last_name_lowercase. In my second project so far this seems to yield more accurate results so you may want to give that a try if the previous answer doesn't work well
EDIT 09-07-2020 Previous edit from 09-03-2020 is partially accurate. During my haste of thinking I had it fully resolved I completely forgot firebase doesn't let you use <, >, <=, >= across different fields. You may need to do two queries and merge them, but you'd probably still be reading more docs than you really intend. Doing the comparison against either the upper or lower version with the appropriate search term seems to give the original results expected from the original answer. For example:
.orderBy("last_name_upper")
.where("last_name_upper", ">=", this.searchForm.text.toUpperCase())
.where("last_name_upper", "<=", this.searchForm.text.toUpperCase() + "\uf8ff")
As firebase documentation, firebase doesn't support full text search.
But to do that you can use third-party tools.
Check this link to learn more https://firebase.google.com/docs/firestore/solutions/search
i was wondering if there is a chance to create comparable properties for objects defined by the user itself.
Following case: In my android app, the user creates a object "car", this object has predefined properties like color, size, doors, engine and so on ... but now, the user wants to add an individual property like "length" ... for that the user gets a plus button under the view to add this property ... now he can type in the wanted property, but what he dont want is to define the type of the input!
The users thinks "hey, its pretty obvious that length is expressed with a number so why i have to choose the type for this?"
I dont want to limit the user if i give them only predefined propertys.
I thought about saving every new parameter as a string, but then the values arent comparable anymore ... "900" is bigger than "1000" in a string comparison and so on. And i want to filter data and do queries later.
I dont disagree at all with the idea to let the user choose which type the field is, but i dont want to ask them too much in an android application.
If this all is not possible, how can i smartly get the information for the type from the user?
How can i handle this problem? Can someone give me a hint or keyword to search for?
Natural sorting might be the thing you are looking for. It will solve the problem with numbers.
First of all excuse me for my very bad English...
I'm a very very new developer and I'm confusing so much with search operation.
Actually I want to make a food and cooking app (with a lot of recipes and so on), and I want to add a search action to it, so the user could put multiple things (such as Ingredients) and the app show him the foods that have these things in their Ingredients.
Now I have two question.
First, how can I add tags to my "recipe activities" so when the ingredient typed app knows which recipes should showes? (My recipes are not in textview, they are all in imageviews).
Second, how can I completely separate the search keywords with ","? for finding the right recipes. (example: type "tomato", "chicken", "egg" and the app shows him/her the recipes that have these things in their Ingredients.)
I know you that now you are laughing so much for my gramer :), so after you laughted enough please answer my questions. Thank You SOOOOOOOOO MUUUUUUUUUCH.
You can use something like a map for every Recipe's ingredients a-la:
class Recipe
-name:String
-ingredients:Map < String, Quantity > or Set < String >
where Quantity represents all that nasty features used in culinary like spoons, cups, pinches.
Then you can search through keys of every recipe's ingredients. Name would be a tag you've mentioned.
You can read search string, parse it (e.g. into array with regular expression) and put into Set to avoid duplicates.
I have a few questions concerning the application I'm designing. I have many different routes I could try in order to get what I wanted, but I thought I would get suggestions instead of doing trial and error.
I'm developing a simple app that has one Game screen (activity) and a main menu to start the game. The game screen will have two buttons, "Next" and "Repeat". Every time "Next" is hit, a new sentence in a different language (with the english translation below it) will appear, audio will pronounce the sentence, and hopefully I can get a highlighter to highlight the part of the sentence being spoken. You can guess what the Repeat button does.
My question is, what do you guys think would be the best way to store these sentences so they can be randomly picked out? I thought about making an array of structures or classes with the English definition, audio, and sentence in each structure. Then using a random iterator to pick one out. However, it would take a long time to do this approach and I wanted to get some ideas before I tried it.
Also, I'm not sure how I would print the sentence and definition on the screen.
Thanks!
Using an array of structs/classes seems like that would be the normal way to go.
Not really sure what you mean by a random iterator, but when picking out random sentences from the array of sentences, you might want to avoid repeats until you've gone through all the elements. To do that, you can make a second array of indices, select one at random from those, use the element that corresponds to that index, and remove that number from the array of indices.
In Java, that would look something like
ArrayList<Sentence> sentences;
ArrayList<Integer> indices;
Random rand;
private void populateIndices() {
for(int i = 0; i < sentences.size(); i++)
indices.add(i);
}
public Sentence getNextSentence() {
if(indices.isEmpty())
populateIndices();
int idx = rand.nextInt(indices.size());
int val = indices.get(idx);
indices.remove(idx);
return sentences.get(val);
}
Quite frankly I would load out of copyright books from Project Gutenberg and randomly pull sentences from them. I would then pass the sentences into Google APIs to translate and pronounce the sentences. Relying on external services is at the very heart of what a connected OS like Android is made for. It would be a much more compelling use of the platform than a canned Rosetta Stone like CD solution and your ability to tap into a broader amount of content would be increased exponentially.