cipher.doFinal() method memory issue

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Java

Hi,
I doing encryption and decryption of document. Initially i read the file in byte array and passed that byte array to my encrypeted method. Upto 50MB size , i am able to encrypt the file without any issue. But if i increase my file SIZE to 80 MB , it is faling in cipher.doFinal() saying outofmemoryException.
So how to encrypt bigger file without any issues? and also is doFinal() method have any size limitation. Please let me know.

Below is my code.
plainText = cipher.doFinal(plainText); error is throwing.

public static byte[] encrypt(byte[] plainText, byte[] key,
			byte[] initialVector) throws NoSuchAlgorithmException,
			NoSuchPaddingException, InvalidKeyException,
			InvalidAlgorithmParameterException, IllegalBlockSizeException,
			BadPaddingException {
		System.out.println("Indside encrypt");
		Cipher cipher = Cipher.getInstance(cipherTransformation);
		System.out
				.println("cipher object created now key specification object creation");
		SecretKeySpec secretKeySpec = new SecretKeySpec(key,
				aesEncryptionAlgorithm);
		System.out.println("key specification object created");
		IvParameterSpec ivParameterSpec = new IvParameterSpec(initialVector);
		cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec, ivParameterSpec);
		System.out.println("cipher init successfull" + plainText.length);
		int bytesLenght = plainText.length;
		
		
			plainText = cipher.doFinal(plainText);
		
		System.out.println("return encrypted bytes");
		return plainText;
	}