How to use (AES) symmetric key cryptography with java

AesDemo.java

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.util.Base64;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;

public class AesDemo {
	
	private static final String ENC_FILE = "encryptedtext.txt";
	private static final String SECRET_KEY_FILE = "secretkey.txt";
	
	public static void main(String[] args) throws Exception{
		KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");
		keyGenerator.init(128);
		SecretKey secretKey = keyGenerator.generateKey();
		ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(SECRET_KEY_FILE));
		oos.writeObject(secretKey);
		oos.close();
		
		Cipher cipher = Cipher.getInstance("AES");
		
		cipher.init(Cipher.ENCRYPT_MODE, secretKey);
		byte[] cipherTextBytes1 = cipher.doFinal("My name is yogesh".getBytes());
		try {
			FileWriter fw = new FileWriter(ENC_FILE);
			BufferedWriter bw = new BufferedWriter(fw);
			bw.write(Base64.getEncoder().encodeToString(cipherTextBytes1));
			bw.close();
		} catch (IOException e) {
			e.printStackTrace();
		}

		byte[] cipherTextBytes2 = null;
		try {
			FileReader fr = new FileReader(ENC_FILE);
			BufferedReader br = new BufferedReader(fr);
			cipherTextBytes2 = Base64.getDecoder().decode(br.readLine());
			br.close();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}

		cipher.init(Cipher.DECRYPT_MODE, secretKey);
		byte[] bytePlainText = cipher.doFinal(cipherTextBytes2);
		System.out.println(new String(bytePlainText));
	}

}