I have an activity that's supposed to display a text file. The text file is 165 kB. Originally, after I read in the text file, I would do something like this,
textView.setText(fileText);
But that took over 10 seconds on my Nexus 4, and I confirmed that this was due to the call to setText() and not reading the file. Then, after searching around a bit, I got the idea to put it in a webview, using WebView.loadData(). This takes less than a second.
I'm curious as to why a WebView is able to load text so much faster than a TextView. Does anyone know?
From what I remember;
The WebView will only render the text that it needs to display at any given time. Meaning that when you first load it will only load 20 - 30 lines of text. Whereas when you call textView.setText(fileText); it causes Android to render all of the text even though it is not displayed. If you are trying to add a lot of text to a TextView then you should use textView.append(fileLine); in a loop which should load quite a bit faster.
Related
I'm just getting started and trying to make a simple app after going through some of the Google Codelabs. I wrote a Choose your own Adventure type of game. It consists of 500 paragraphs, and at the end of each paragraph is usually a choice of the next action to take (ie paragraph to load) and possibly some game logic. For now I am concentrating on the text only.
It seems simpler to make 500 text files and load up whatever file number is necessary, however it makes more sense to load ALL the paragraphs as the entire text takes up roughly 300Kb as a text file.
How would I even attempt this? I know I would need a text array and I file reader. I think it would be more work to format the paragraphs with a delineator to separate them, as it may be simpler to just create 500 files and write a While loop feeding my array.
That should fulfill my current objective, but when I want to add the choices at the end of the paragraphs, it seems as if a JSON or XML file that includes the text and choices would be better. I could not figure out how to even attempt this.
Example Paragraph: "You hear a horseman galloping and spin towards the sound. Do you have the skill of Forest Stealth? If you do, turn to 95. If you do not, turn to 234."
How to show very large string (let's say 25 MB or more maybe even 50MB) without any paragraphs or spaces in a TextView? There no TextRecyclerView in Android. If you directly try to load into TextView you just get ANR straight away.
If you split in chucks and put it in RecycleView in a different screens and rotation the text will be look different. It should behave as single TextView.
For simplicity our file stored in raw or assets folder and called large_string.txt.
How to solve such problem and show this huge string with scrolling smoothly without any lag?
I have a huge image to render (1024x25373p) cut into 99 images of 1024x256p.
I have tried to use a ListView, but without success : it crashes when scrolling, whithout any error (exept one line saying the proccess was stopped).
So, my question is, how do I render this huge image ?
Please note that I have tried to use TileView by moagrius, without success (I can't get it to work with navigation drawer)
As a suggestion ,
If this is listview, you may not need such larger size images "1024x256p" .
Actual size of your imageView may much for less than that. So its a wastage of
heap if you try to load those images directly without some processing.
Definitly you need to do some scaling down for your image based on actual size that you need. Nice exapmple and code has been published on the official doc
You need to deallocate memory or clear the all bitmaps which are not visible on the listview for particular moment.
You can use progressing loader in order to load your images in to the listview. Then loading will be happen based on the scrolling.
Also you can define lager heap enable in your manifest though it is not recommended but has to do in highly memory consumable apps.
android:largeHeap="true"
I need some help,
I am creating an app, and want it to run faster I mean when the app is started first it shows a blank white screen for o 1-2 seconds and then loads images. I have a layout background image, and 4 imageviews which are clickable and take you to the next activity. I read somewhere i should use threads to load images and it will load them on a separate thread faster, but i have some problem using it.
So here are the problems and android studio explanations:
Thread thread=new Thread(
public void run(){
ImageView tipka=(ImageView)findViewById(R.id.tipkaproba);
tipka.setImageResource(R.drawable.instructions);
LinearLayout asd=(LinearLayout)findViewById(R.id.layoutproba);
asd.setBackgroundResource(R.drawable.backfround123);
}
).start();
Now the android studio says:
After
"Thread(" )expected
Before
"public void run(){"
; expected
On ").start();"
Invalid method declaration; return type required, Missing method body, or declare abstract.
Now i would like to know:
Does this speed up loading images, ( if not how to do it then)
How to fix my errors.
Thanks anyway !
Do all images fit in the screen?! If users need to scroll to view other images why load all of them at once? Use a grid view with adapter to load the image. In this way when the app start only images on the screen will be loaded and then when the user scrolls other images show up!
another thing you can do is to have 2 version of each image. one low quality with small size that loads first and one for high quality image. that will load latter. You can also calculate the base color for each image (use open source code or do it manually). then set the background image of iamgeview to this color. So when the image finally loads on the screen. The difference is not as dramatic as it was before.
If you want to use thread try AsyncTask first. Using AsyncTask is simpler than defining thread yourself.
Try to decrease the size of your images! If you be able to do this. it works better than any other trick! It's mobile, you don't have to show supper high quality images. users don't even notice most of the time
You probably took care of this but it worth mentioning that you need to provide different images for different screen densities and it's critical for performance as well as quality.
I have been looking for a while but haven't been able to find an answer. I have a text view in my APK that needs to potentially handle large amounts of text being appended to it a little at a time. So it could grow over time as stuff streams to it. So far I haven't seen any issues and I have let the underlying Android implementation take care of the data. Does anyone know if Android caches these all in memory or that if it passes a watermark level it could then write to file for the TextView? What if it gets too huge, would the APK run out of memory and get killed by Dalvik? If that is the case I am open for any suggestion as how to mitigate this possiblity. One solution in my mind is that have a custom textview that does exactly what I explained and caches data to file if it passes a water mark. However, I am not sure how tricky it would get to detect where the user is navigating within the TextView to pull the data back and forth from the underlying data file and populate the actual TextView object.
Thanks
While I was unable to find the actual threshold, it has been discussed and suggested that extremely long text be displayed in smaller chunks. You can also write to a file which you can then read back in as necessary for your project.
Edit: regarding the TextView bookmark (for lack of a better term), you could always programmatically check to see where the user is in the TextView (checking for a certain character or string at the end of the TextView) and reading the next few lines of text into the TextView. You would have to match the getText().toString() value of the TextView against the readable text in your file.
I'm wondering now too if you would be able to do that in either direction. To save space, you could write your text to file as the user needs it, and update the TextView to only display 5 or 6 lines (arbitrary number). You could trim the TextView in either direction to save memory. You could ellipsize both sides of your text, scroll enable it, and trim/read those points as necessary.