Java Tutorials and Best Practices
This tutorial shows several ways for reading input from a console in Java. Before listing the ways, it’s worth to define System.in as it’s used by most reading ways. System.in is a static field of type InputStream representing the stream which corresponds to keyboard input or any other input source specified by the host machine. 1- BufferedReader The oldest way...
This tutorial shows several ways to convert a File object to a byte[] array in Java. 1- Traditional way The traditional conversion way is through using read() method of InputStream as the following:
1 2 3 4 5 6 7 8 9 10 11 12 13 | public static byte[] convertUsingTraditionalWay(File file) { byte[] fileBytes = new byte[(int) file.length()]; try(FileInputStream inputStream = new FileInputStream(file)) { inputStream.read(fileBytes); } catch (Exception ex) { ex.printStackTrace(); } return fileBytes; } |
2- Java NIO With Java 7, you can do the conversion using Files utility class of nio package:
1 2 3 4 5 6 7 8 9 10 11 12 13 | public static byte[] convertUsingJavaNIO(File file) { byte[] fileBytes = null; try { fileBytes = Files.readAllBytes(file.toPath()); } catch (Exception ex) { ex.printStackTrace(); } return fileBytes; } |
3- Apache Commons IO Besides JDK, you can...
This tutorial shows several ways to convert an InputStream to a String in Java. 1- BufferedReader The common way for generating a String out of an InputStream is through using BufferedReader as the following:
1 2 3 4 5 6 7 8 9 10 11 12 13 | public static String convertInputStreamToStringBufferredReader(InputStream is) throws IOException { StringBuilder output = new StringBuilder(); try(Reader reader = new BufferedReader(new InputStreamReader(is, Charset.forName(StandardCharsets.UTF_8.name())))) { int c = 0; while((c = reader.read()) != -1){ output.append((char) c); } } return output.toString(); } |
2- Scanner Another common way is to use a Scanner object as the following:
1 2 3 4 5 6 7 8 9 10 | public static String convertInputStreamToStringScanner(InputStream is) throws IOException { String output = null; try(Scanner scanner = new Scanner(is, StandardCharsets.UTF_8.name()).useDelimiter("\\A")) { output = scanner.hasNext() ? scanner.next() : ""; } return output; } |
3- Java 8 With Java 8, you can generate a...
This tutorial shows several ways to convert InputStream to File in Java. 1- Common way The common way for converting InputStream to File is through using OutputStream. You can’t directly create a File object from InputStream. However, you can read the InputStream and write it to a File using FileOutputStream as the following:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 | public static void convertInputStreamToFileCommonWay(InputStream is) throws IOException { OutputStream outputStream = null; try { File file = new File("C:\\Users\\user\\Desktop\\test\\output.txt"); outputStream = new FileOutputStream(file); int read = 0; byte[] bytes = new byte[1024]; while ((read = is.read(bytes)) != -1) { outputStream.write(bytes, 0, read); } } finally { if(outputStream != null) { outputStream.close(); } } } |
2- java.nio (Java 8) Using nio...