Utils to read resource text file to String Java

Question

Is there any utility that helps to read a text file in the resource into a String  I suppose this is a popular requirement  but I couldn t find any utility after Googling

User · Accepted Answer

Yes  Guava provides this in the Resources class  For example   URL url   Resources getResource  foo txt    String text   Resources toString url  StandardCharsets UTF 8

User · Answer

Here s a solution using Java 11 s Files readString   public class Utils       public static String readResource String name  throws URISyntaxException  IOException           var uri   Utils class getResource       name  toURI            var path   Paths get uri           return Files readString path

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Pure and simple  jar-friendly  Java 8  solution  This simple method below will do just fine if you re using Java 8 or greater          Reads given resource file as a string         param fileName path to the resource file     return the file s contents     throws IOException if read fails for any reason     static String getResourceFileAsString String fileName  throws IOException       ClassLoader classLoader   ClassLoader getSystemClassLoader        try  InputStream is   classLoader getResourceAsStream fileName             if  is    null  return null          try  InputStreamReader isr   new InputStreamReader is                BufferedReader reader   new BufferedReader isr                 return reader lines   collect Collectors joining System lineSeparator                          And it also works with resources in jar files   About text encoding  InputStreamReader will use the default system charset in case you don t specify one  You may want to specify it yourself to avoid decoding problems  like this   new InputStreamReader isr  StandardCharsets UTF 8       Avoid unnecessary dependencies  Always prefer not depending on big  fat libraries  Unless you are already using Guava or Apache Commons IO for other tasks  adding those libraries to your project just to be able to read from a file seems a bit too much    Simple  method  You must be kidding me  I understand that pure Java does not do a good job when it comes to doing simple tasks like this  For instance  this is how we read from a file in Node js   const fs   require  fs    const contents   fs readFileSync  some-file txt    utf-8      Simple and easy to read  although people still like to rely on many dependencies anyway  mostly due to ignorance   Or in Python   with open  some-file txt    r   as f      content   f read     It s sad  but it s still simple for Java s standards and all you have to do is copy the method above to your project and use it  I don t even ask you to understand what is going on in there  because it really doesn t matter to anyone  It just works  period  -

User · Answer

If you include Guava  then you can use   String fileContent   Files asCharSource new File filename   Charset forName  UTF-8    read       Other solutions mentioned other method for Guava but they are deprecated

User · Answer

I ve written readResource   methods here  to be able to do it in one simple invocation  It depends on the Guava library  but I like JDK-only methods suggested in other answers and I think I ll change these that way

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I made NO-dependency static method like this    import java nio file Files  import java nio file Paths   public class ResourceReader       public  static String asString String resourceFIleName            try                return new String Files readAllBytes Paths get new CheatClassLoaderDummyClass   getClass   getClassLoader   getResource resourceFIleName  toURI                 catch  Exception e                throw new RuntimeException e                     class CheatClassLoaderDummyClass   cheat class loader - for sql file loading

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public static byte   readResoureStream String resourcePath  throws IOException       ByteArrayOutputStream byteArray   new ByteArrayOutputStream        InputStream in   CreateBffFile class getResourceAsStream resourcePath          Create buffer     byte   buffer   new byte 4096       for                int nread   in read buffer           if  nread  lt   0                break                    byteArray write buffer  0  nread             return byteArray toByteArray       Charset charset   StandardCharsets UTF 8  String content   new   String FileReader readResoureStream   resource      txt    charset   String lines     content split    n

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Guava also has Files readLines   if you want a return value as List lt String gt  line-by-line   List lt String gt  lines   Files readLines new File   file path input txt    Charsets UTF 8     Please refer to here to compare 3 ways  BufferedReader vs  Guava s Files vs  Guava s Resources  to get String from a text file

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I like akosicki s answer with the Stupid Scanner Trick  It s the simplest I see without external dependencies that works in Java 8  and in fact all the way back to Java 5   Here s an even simpler answer if you can use Java 9 or higher  since InputStream readAllBytes   was added at Java 9    String text   new String AppropriateClass class getResourceAsStream  foo txt   readAllBytes

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You can use the old Stupid Scanner trick oneliner to do that without any additional dependency like guava   String text   new Scanner AppropriateClass class getResourceAsStream  foo txt     UTF-8   useDelimiter    A   next      Guys  don t use 3rd party stuff unless you really need that  There is a lot of functionality in the JDK already

User · Answer

You can use the following code  form Java   new String Files readAllBytes Paths get getClass   getResource  example txt   toURI

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apache-commons-io has a utility name FileUtils   URL url   Resources getResource  myFile txt    File myFile   new File url toURI      String content   FileUtils readFileToString myFile   UTF-8        or any other encoding

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I often had this problem myself  To avoid dependencies on small projects  I often write a small utility function when I don t need commons io or such  Here is the code to load the content of the file in a string buffer    StringBuffer sb   new StringBuffer     BufferedReader br   new BufferedReader new InputStreamReader getClass   getResourceAsStream  path to textfile txt     UTF-8     for  int c   br read    c    -1  c   br read    sb append  char c    System out println sb toString          Specifying the encoding is important in that case  because you might have edited your file in UTF-8  and then put it in a jar  and the computer that opens the file may have CP-1251 as its native file encoding  for example   so in this case you never know the target encoding  therefore the explicit encoding information is crucial  Also the loop to read the file char by char seems inefficient  but it is used on a BufferedReader  and so actually quite fast

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If you want to get your String from a project resource like the file testcase foo json in src main resources in your project  do this   String myString    new String Files readAllBytes Paths get getClass   getClassLoader   getResource  testcase foo json   toURI         Note that the getClassLoader   method is missing on some of the other examples

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The following cods work for me   compile group   commons-io   name   commons-io   version   2 6    Value  classpath mockResponse json   private Resource mockResponse   String mockContent   FileUtils readFileToString mockResponse getFile     UTF-8

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With set of static imports  Guava solution can be very compact one-liner   toString getResource  foo txt    UTF 8     The following imports are required   import static com google common io Resources getResource import static com google common io Resources toString import static java nio charset StandardCharsets UTF 8

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yegor256 has found a nice solution using Apache Commons IO   import org apache commons io IOUtils   String text   IOUtils toString this getClass   getResourceAsStream  foo xml                                    UTF-8

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I m using the following for reading resource files from the classpath   import java io IOException  import java io InputStream  import java net URISyntaxException  import java util Scanner   public class ResourceUtilities       public static String resourceToString String filePath  throws IOException  URISyntaxException               try  InputStream inputStream   ResourceUtilities class getClassLoader   getResourceAsStream filePath                         return inputStreamToString inputStream                        private static String inputStreamToString InputStream inputStream                try  Scanner scanner   new Scanner inputStream  useDelimiter    A                          return scanner hasNext     scanner next                             No third party dependencies required

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I like Apache commons utils for this type of stuff and use this exact use-case  reading files from classpath  extensively when testing  especially for reading JSON files from  src test resources as part of unit   integration testing  e g   public class FileUtils        public static String getResource String classpathLocation            try               String message   IOUtils toString FileUtils class getResourceAsStream classpathLocation                       Charset defaultCharset                 return message                    catch  IOException e                throw new RuntimeException  Could not read file       classpathLocation       from classpath   e                        For testing purposes  it can be nice to catch the IOException and throw a RuntimeException - your test class could look like e g        Test     public void shouldDoSomething              String json   FileUtils getResource   json input json                Use json as part of test

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Use Apache commons s FileUtils  It has a method readFileToString

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package test   import java io InputStream  import java nio charset StandardCharsets  import java util Scanner   public class Main       public static void main String   args            try               String fileContent   getFileFromResources  resourcesFile txt                System out println fileContent             catch  Exception e                e printStackTrace                           USE THIS FUNCTION TO READ CONTENT OF A FILE  IT MUST EXIST IN  RESOURCES  FOLDER     public static String getFileFromResources String fileName  throws Exception           ClassLoader classLoader   Main class getClassLoader            InputStream stream   classLoader getResourceAsStream fileName           String text   null          try  Scanner scanner   new Scanner stream  StandardCharsets UTF 8 name                   text   scanner useDelimiter    A   next                      return text

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Here is my approach worked fine   public String getFileContent String fileName        String filePath    myFolder     fileName    json       try InputStream stream   Thread currentThread   getContextClassLoader   getResourceAsStream filePath             return IOUtils toString stream   UTF-8          catch  IOException e               Please print your Exception

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At least as of Apache commons-io 2 5  the IOUtils toString   method supports an URI argument and returns contents of files located inside jars on the classpath   IOUtils toString SomeClass class getResource      toURI

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For java 7   new String Files readAllBytes Paths get getClass   getResource  foo txt   toURI

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Guava has a  toString  method for reading a file into a String   import com google common base Charsets  import com google common io Files   String content   Files toString new File   home x1 text log    Charsets UTF 8     This method does not require the file to be in the classpath  as in Jon Skeet previous answer

[java] Utils to read resource text file to String (Java)

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