Java Utililty Methods Key Pair Create

KeyGenerator keyGenerator = KeyGenerator.getInstance(KEY_ALGORITHM);
keyGenerator.init(128);
SecretKey secretKey = keyGenerator.generateKey();
return secretKey.getEncoded();

SecureRandom random = SecureRandom.getInstanceStrong();
KeyGenerator keyGen = KeyGenerator.getInstance("AES");
keyGen.init(KEY_SIZE_IN_BITS, random);
SecretKey key = keyGen.generateKey();
return new String(Base64.getEncoder().encode(key.getEncoded()), "UTF-8");

StringBuilder sb = new StringBuilder();
String uuid = UUID.randomUUID().toString().replace("-", "");
for (int i = 0; i < 8; i++) {
    String str = uuid.substring(i * 4, i * 4 + 4);
    int x = Integer.parseInt(str, 16);
    sb.append(chars[x % 0x3E]);
return sb.toString();
...

KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");
keyGenerator.init(AES_KEYLENGTH);
return keyGenerator.generateKey();

try {
    final KeyPairGenerator keyGen = KeyPairGenerator.getInstance(ALGORITHM);
    keyGen.initialize(512);
    final KeyPair key = keyGen.generateKeyPair();
    File privateKeyFile = new File(PRIVATE_KEY_FILE);
    File publicKeyFile = new File(PUBLIC_KEY_FILE);
    if (privateKeyFile.getParentFile() != null) {
        privateKeyFile.getParentFile().mkdirs();
...

Key key = new SecretKeySpec("NotARandomKeyYes".getBytes(), "AES");
return key;

try {
    KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");
    keyGenerator.init(128);
    SecretKey key = keyGenerator.generateKey();
    return key.getEncoded();
} catch (NoSuchAlgorithmException e) {
return null;
...

KeyGenerator keyGenerator = KeyGenerator.getInstance(ALGO);
keyGenerator.init(KEYSZ);
SecretKey key = keyGenerator.generateKey();
return key;

Key key = new SecretKeySpec(keyValue, ALGO);
return key;

Key key = new SecretKeySpec(SECRET_KEY, ALGORITHM);
return key;