How to Silently Close Resources in Java?

The following piece of code describes how to silently and properly close a stream resource in Java:

File f = new File("SomeFile.txt");
FileOutputStream fos = null;

try {

    fos = new FileOutputStream(f);<

    // Do something...

} catch (FileNotFoundException ex) {

    // Display error message

} finally {

    // Closing resource
    if ( fos != null )  {

        try {

            fos.close();

        } catch (IOException ex) {

            // Silently ignore it

        }

    }

}

Yet, the amount of code required to close each stream in finally is nothing but clutter which does not help with readability too. Fortunately, the Apache Commons library offers a tool solving this issue:

} finally {

    IOUtils.closeQuietly(out);

}

How to Convert a Byte Array Into an Hexadecimal String?

Trying to convert a byte array into an hexadecimal and back to the same byte array manually, can be tricky. The Hex class of the Apache Commons library offers a solution:

byte[] ba = { 4, 55, -27, 99, 42, 0, -1 };

String toHex = Hex.encodeHexString(ba);
byte[] retr = Hex.decodeHex(toHex.toCharArray());

System.out.println("Hexadecimal : " + toHex);
System.out.println("Expected    : " + Arrays.toString(ba));
System.out.println("Retrieved   : " + Arrays.toString(retr));

ba = new byte[0];
toHex = Hex.encodeHexString(ba);
retr = Hex.decodeHex(toHex.toCharArray());

System.out.println("Hexadecimal : " + toHex);
System.out.println("Expected    : " + Arrays.toString(ba));
System.out.println("Retrieved   : " + Arrays.toString(retr));

The generated output is:

Hexadecimal : 0437e5632a00ff
Expected    : [4, 55, -27, 99, 42, 0, -1]
Retrieved   : [4, 55, -27, 99, 42, 0, -1]

Hexadecimal :
Expected    : []
Retrieved   : []

More Java tips & tricks here.