I am trying to read a simple text file into a String. Of course there is the usual way of getting the input stream and iterating with readLine() and reading contents into String.
Having done this hundreds of times in past, I just wondered how can I do this in minimum lines of code? Isn't there something in java like String fileContents = XXX.readFile(myFile/*File*/) .. rather anything that looks as simple as this?
I know there are libraries like Apache Commons IO which provide such simplifications or even I can write a simple Util class to do this. But all that I wonder is - this is a so frequent operation that everyone needs then why doesn't Java provide such simple function? Isn't there really a single method somewhere to read a file into string with some default or specified encoding?
Don't write your own util class to do this - I would recommend using Guava, which is full of all kinds of goodness. In this case you'd want either the Files class (if you're really just reading a file) or CharStreams for more general purpose reading. It has methods to read the data into a list of strings (readLines) or totally (toString).
It has similar useful methods for binary data too. And then there's the rest of the library...
I agree it's annoying that there's nothing similar in the standard libraries. Heck, just being able to supply a CharSet to a FileReader would make life a little simpler...
You can use apache commons IO..
FileInputStream fisTargetFile = new FileInputStream(new File("test.txt"));
String targetFileStr = IOUtils.toString(fisTargetFile, "UTF-8");
I discovered that the accepted answer actually doesn't always work, because \\Z may occur in the file. Another problem is that if you don't have the correct charset a whole bunch of unexpected things may happen which may cause the scanner to read only a part of the file.
The solution is to use a delimiter which you are certain will never occur in the file. However, this is theoretically impossible. What we CAN do, is use a delimiter that has such a small chance to occur in the file that it is negligible: such a delimiter is a UUID, which is natively supported in Java.
String content = new Scanner(file, "UTF-8")
.useDelimiter(UUID.randomUUID().toString()).next();
Sadly, no.
I agree that such frequent operation should have easier implementation than copying of input line by line in loop, but you'll have to either write helper method or use external library.
From Java 7 (API Description) onwards you can do:
new String(Files.readAllBytes(Paths.get(filePath)), StandardCharsets.UTF_8);
Where filePath is a String representing the file you want to load.
Using Apache Commons IO.
import org.apache.commons.io.FileUtils;
//...
String contents = FileUtils.readFileToString(new File("/path/to/the/file"), "UTF-8")
You can see de javadoc for the method for details.
This should work for you:
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
public static void main(String[] args) throws IOException {
String content = new String(Files.readAllBytes(Paths.get("abc.java")));
}
Another alternative approach is:
How do I create a Java string from the contents of a file?
Other option is to use utilities provided open source libraries
http://commons.apache.org/io/api-1.4/index.html?org/apache/commons/io/IOUtils.html
Why java doesn't provide such a common util API ?
a) to keep the APIs generic so that encoding, buffering etc is handled by the programmer.
b) make programmers do some work and write/share opensource util libraries :D ;-)
Source: Stackoverflow.com