Java

byte[] keyBytes, ivBytes;
// Populate keyBytes and ivBytes with byte arrays of length 16 bytes (128 bits)

final SecretKey key = new SecretKeySpec(keyBytes, "AES");
final IvParameterSpec iv = new IvParameterSpec(ivBytes);

final Cipher encrypt = Cipher.getInstance("AES/CBC/PKCS5Padding");
final Cipher decrypt = Cipher.getInstance("AES/CBC/PKCS5Padding");

encrypt.init(Cipher.ENCRYPT_MODE, key, iv);
decrypt.init(Cipher.DECRYPT_MODE, key, iv);

final ByteArrayOutputStream outBytes = new ByteArrayOutputStream();
final CipherOutputStream out = new CipherOutputStream(outBytes, encrypt);

out.write("This is a test, of course.".getBytes());
out.close();

final byte[] encryptedBytes = outBytes.toByteArray();
final ByteArrayInputStream inBytes = new ByteArrayInputStream(encryptedBytes);
final CipherInputStream in = new CipherInputStream(inBytes, decrypt);

final byte[] result = new byte[100];
final int byteCount = in.read(result);

System.out.print('"');
System.out.print(new String(result, 0, byteCount));
System.out.println('"');