read file from assets

Question

public class Utils       public static List lt Message gt  getMessages               File file   new File  file    android asset helloworld txt            AssetManager assetManager   getAssets            InputStream ims   assetManager open  helloworld txt                   I am using this code trying to read a file from assets  I tried two ways to do this  First  when use File I received FileNotFoundException  when using AssetManager getAssets   method isn t recognized   Is there any solution here

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getAssets   method will work when you are calling inside the Activity class   If you calling this method in non-Activity class then you need to call this method from Context which is passed from Activity class  So below is the line by you can access the method   ContextInstance getAssets      ContextInstance may be passed as this of Activity class

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getAssets     is only works in Activity in other any class you have to use Context for it   Make a constructor for Utils class pass reference of activity  ugly way  or context of application as a parameter to it  Using that use getAsset   in your Utils class

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Here is a way to get an InputStream for a file in the assets folder without a Context  Activity  Fragment or Application   How you get the data from that InputStream is up to you   There are plenty of suggestions for that in other answers here   Kotlin  val inputStream   ClassLoader  class java classLoader  getResourceAsStream  assets your file ext     Java  InputStream inputStream   ClassLoader class getClassLoader   getResourceAsStream  assets your file ext      All bets are off if a custom ClassLoader is in play

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one line solution for kotlin  fun readFileText fileName  String   String       return assets open fileName  bufferedReader   use   it readText        Also you can use it as extension function everyWhere fun Context readTextFromAsset fileName   String    String       return assets open fileName  bufferedReader   use         it readText       Simply call in any context Class context readTextFromAsset  quot my file name quot

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Reading and writing files have always been verbose and error-prone  Avoid these answers and just use Okio instead   public void readLines File file  throws IOException     try  BufferedSource source   Okio buffer Okio source file          for  String line   line   source readUtf8Line       null            if  line contains  square              System out println line

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HpTerm answer Kotlin version  private fun getDataFromAssets activity  Activity   String       var bufferedReader  BufferedReader    null     var data    quot  quot       try           bufferedReader   BufferedReader              InputStreamReader                  activity  assets  open  quot Your FILE html quot                     quot UTF-8 quot                                             use assets  directly if in activity          var mLine String    bufferedReader readLine           while  mLine    null                data   mLine             mLine bufferedReader readLine                    catch  e  Exception            e printStackTrace         finally           try               bufferedReader  close             catch  e  Exception                e printStackTrace                       return data

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Here is a method to read a file in assets          Reads the text of an asset  Should not be run on the UI thread          param mgr               The   link AssetManager  obtained via   link Context getAssets        param path               The path to the asset      return The plain text of the asset     public static String readAsset AssetManager mgr  String path        String contents           InputStream is   null      BufferedReader reader   null      try           is   mgr open path           reader   new BufferedReader new InputStreamReader is            contents   reader readLine            String line   null          while   line   reader readLine       null                contents      n    line                  catch  final Exception e            e printStackTrace          finally           if  is    null                try                   is close                  catch  IOException ignored                                    if  reader    null                try                   reader close                  catch  IOException ignored                                      return contents

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public String ReadFromfile String fileName  Context context        StringBuilder returnString   new StringBuilder        InputStream fIn   null      InputStreamReader isr   null      BufferedReader input   null      try           fIn   context getResources   getAssets                    open fileName  Context MODE WORLD READABLE           isr   new InputStreamReader fIn           input   new BufferedReader isr           String line               while   line   input readLine       null                returnString append line                   catch  Exception e            e getMessage          finally           try               if  isr    null                  isr close                if  fIn    null                  fIn close                if  input    null                  input close              catch  Exception e2                e2 getMessage                        return returnString toString

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You can load the content from the file  Consider the file is present in asset folder   public static InputStream loadInputStreamFromAssetFile Context context  String fileName       AssetManager am   context getAssets        try           InputStream is   am open fileName           return is        catch  IOException e            e printStackTrace              return null     public static String loadContentFromFile Context context  String path       String content   null      try           InputStream is   loadInputStreamFromAssetFile context  path           int size   is available            byte   buffer   new byte size           is read buffer           is close            content   new String buffer   UTF-8          catch  IOException ex            ex printStackTrace            return null            return content      Now you can get the content by calling the function as follow  String json  FileUtil loadContentFromFile context   data json      Considering the data json is stored at Application app src main assets data json

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In MainActivity java   Override     protected void onCreate Bundle savedInstanceState            super onCreate savedInstanceState           setContentView R layout activity main            TextView tvView    TextView  findViewById R id tvView            AssetsReader assetsReader   new AssetsReader this           if assetsReader getTxtFile your file title      null                        tvView setText assetsReader getTxtFile your file title                       Also  you can create separate class that does all the work  public class AssetsReader implements Readable       private static final String TAG    AssetsReader         private AssetManager mAssetManager      private Activity mActivity       public AssetsReader Activity activity            this mActivity   activity          mAssetManager   mActivity getAssets                Override     public String getTxtFile String fileName                BufferedReader reader   null          InputStream inputStream   null          StringBuilder builder   new StringBuilder             try              inputStream   mAssetManager open fileName               reader   new BufferedReader new InputStreamReader inputStream                 String line               while  line   reader readLine       null                                Log i TAG  line                   builder append line                   builder append   n                            catch  IOException ioe               ioe printStackTrace              finally                if inputStream    null                                try                       inputStream close                      catch  IOException ioe                       ioe printStackTrace                                                 if reader    null                                try                       reader close                      catch  IOException ioe                                        ioe printStackTrace                                                      Log i TAG   builder toString        builder toString             return builder toString              In my opinion it s better to create an interface  but it s not neccessary   public interface Readable                  Reads txt file from assets         param fileName         return string             String getTxtFile String fileName

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Here is what I do in an activity for buffered reading extend modify to match your needs  BufferedReader reader   null  try       reader   new BufferedReader          new InputStreamReader getAssets   open  filename txt              do reading  usually loop until end of file reading       String mLine      while   mLine   reader readLine       null             process line                    catch  IOException e          log the exception   finally       if  reader    null             try                reader close               catch  IOException e                   log the exception                      EDIT   My answer is perhaps useless if your question is on how to do it outside of an activity  If your question is simply how to read a file from asset then the answer is above   UPDATE    To open a file specifying the type simply add the type in the InputStreamReader call as follow   BufferedReader reader   null  try       reader   new BufferedReader          new InputStreamReader getAssets   open  filename txt     UTF-8              do reading  usually loop until end of file reading      String mLine      while   mLine   reader readLine       null             process line                    catch  IOException e          log the exception   finally       if  reader    null             try                reader close               catch  IOException e                   log the exception                      EDIT  As  Stan says in the comment  the code I am giving is not summing up lines  mLine is replaced every pass  That s why I wrote   process line  I assume the file contains some sort of data  i e a contact list  and each line should be processed separately   In case you simply want to load the file without any kind of processing you will have to sum up mLine at each pass using StringBuilder   and appending each pass   ANOTHER EDIT  According to the comment of  Vincent I added the finally block   Also note that in Java 7 and upper you can use try-with-resources to use the AutoCloseable and Closeable features of recent Java    CONTEXT  In a comment  LunarWatcher points out that getAssets   is a class in context  So  if you call it outside of an activity you need to refer to it and pass the context instance to the activity   ContextInstance getAssets      This is explained in the answer of  Maneesh  So if this is useful to you upvote his answer because that s him who pointed that out

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Better late than never   I had difficulties reading files line by line in some circumstances  The method below is the best I found  so far  and I recommend it   Usage  String yourData   LoadData  YourDataFile txt     Where YourDataFile txt is assumed to reside in assets    public String LoadData String inFile            String tContents            try           InputStream stream   getAssets   open inFile            int size   stream available            byte   buffer   new byte size           stream read buffer           stream close            tContents   new String buffer         catch  IOException e               Handle exceptions here            return tContents

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AssetManager assetManager   getAssets    InputStream inputStream   null  try       inputStream   assetManager open  helloworld txt      catch  IOException e       Log e  message    e getMessage

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It maybe too late but for the sake of others who look for the peachy answers    public static String loadAssetFile Context context  String fileName        try           BufferedReader bufferedReader   new BufferedReader new InputStreamReader context getAssets   open fileName             StringBuilder out  new StringBuilder            String eachline   bufferedReader readLine            while  eachline    null                out append eachline               eachline   bufferedReader readLine                      return out toString          catch  IOException e            Log e  Load Asset File  e toString               return null

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The Scanner class  may simplify this           StringBuilder sb new StringBuilder            Scanner scanner null          try               scanner new Scanner getAssets   open  text txt                 while scanner hasNextLine                     sb append scanner nextLine                     sb append   n                            catch  IOException e                e printStackTrace             finally               if scanner  null  try scanner close    catch  Exception e                       mTextView setText sb toString

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If you use other any class other than Activity  you might want to do like   BufferedReader bufferedReader   new BufferedReader new InputStreamReader  YourApplication getInstance   getAssets   open  text txt     UTF-8

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cityfile txt     public void getCityStateFromLocal             AssetManager am   getAssets            InputStream inputStream   null          try               inputStream   am open  city state txt              catch  IOException e                e printStackTrace                      ObjectMapper mapper   new ObjectMapper            Map lt String  String   gt  map   new HashMap lt String  String   gt             try               map   mapper readValue getStringFromInputStream inputStream   new TypeReference lt Map lt String  String   gt  gt                                catch  IOException e                e printStackTrace                      ConstantValues arrayListStateName clear            ConstantValues arrayListCityByState clear            if  map size    gt  0                        for  Map Entry lt String  String   gt  e   map entrySet                      CityByState cityByState   new CityByState                    String key   e getKey                    String   value   e getValue                    ArrayList lt String gt  s   new ArrayList lt String gt  Arrays asList value                    ConstantValues arrayListStateName add key                   s add 0  Select City                    cityByState addValue s                   ConstantValues arrayListCityByState add cityByState                                   ConstantValues arrayListStateName add 0  Select States              Convert InputStream to String     public String getStringFromInputStream InputStream is            BufferedReader br   null          StringBuilder sb   new StringBuilder            String line          try               br   new BufferedReader new InputStreamReader is                while   line   br readLine       null                    sb append line                           catch  IOException e                e printStackTrace              finally               if  br    null                    try                       br close                      catch  IOException e                        e printStackTrace                                                       return sb

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Using Kotlin  you can do the following to read a file from assets in Android   try       val inputStream InputStream   assets open  helloworld txt       val inputString   inputStream bufferedReader   use it readText        Log d TAG inputString    catch  e Exception       Log d TAG  e toString

[android] read file from assets

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