read complete file without using loop in java

Question

Java 7 one line solution

List<String> lines = Files.readAllLines(Paths.get("file"), StandardCharsets.UTF_8);

or

 String text = new String(Files.readAllBytes(Paths.get("file")), StandardCharsets.UTF_8);

If the file is small, you can read the whole data once:

File file = new File("a.txt");
FileInputStream fis = new FileInputStream(file);
byte[] data = new byte[(int) file.length()];
fis.read(data);
fis.close();

String str = new String(data, "UTF-8");

You can try using Scanner if you are using JDK5 or higher.

Scanner scan = new Scanner(file);  
scan.useDelimiter("\\Z");  
String content = scan.next(); 

Or you can also use Guava

String data = Files.toString(new File("path.txt"), Charsets.UTF8);

If you are using Java 5/6, you can use Apache Commons IO for read file to string. The class org.apache.commons.io.FileUtils contais several method for read files.

e.g. using the method FileUtils#readFileToString:

File file = new File("abc.txt");
String content = FileUtils.readFileToString(file);

Since Java 11 you can do it even simpler:

import java.nio.file.Files;

Files.readString(Path path);
Files.readString​(Path path, Charset cs)

Source: https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/nio/file/Files.html#readString(java.nio.file.Path)