1. Where can you find out all those Platform MBean Object Names ?
2. How would you connect via JMX with username and password programmatically ?

1. Where can you find out all those Platform MBean Object Names ?

java.lang.management.ManagementFactory

2. How would you connect via JMX with username and password programmatically ?

    Map<String,String[]> env = new HashMap<String,String[]>();
    env.put(JMXConnector.CREDENTIALS, new String[]{"username", "password"});
    final String url = "service:jmx:rmi://" + host + "/jndi/rmi://" + host + ":" + port + "/jmxrmi";
    JMXServiceURL jmxServiceUrl = new JMXServiceURL(url);
    JMXConnector conn = JMXConnectorFactory.connect(jmxServiceUrl, env);
    MBeanServerConnection mbsc = conn.getMBeanServerConnection();
    ...

# posted by rot13(Unafba Pune) @ 3:43 PM 0 comments

1. Given a byte, how would you turn the nth bit on ?
2. Given a byte, how would you turn the nth bit off ?
3. Given a long, how would you return 8 bytes (in big-endian order) containing the two's-complement binary representation of the long ?
4. Given 8 bytes (in big-endian order) containing the two's-complement binary representation of a long, how would you return the long ?
5. Given a UUID, how would you return a BigInteger representing the numeric value of the underlying 128-bit ?

1. Given a byte, how would you turn the nth bit on ?

       public static byte setBitOn(byte b, int n) {
           return (byte)(b | 1 << n);
       }

2. Given a byte, how would you turn the nth bit off ?

       public static byte setBitOff(byte b, int n) {
           int mask = 0xFF - (1 << n);
           return (byte)(b & mask);
       }

3. Given a long, how would you return 8 bytes (in big-endian order) containing the two's-complement binary representation of the long ?

       public static byte[] longTobytes(long val) {
           ByteBuffer bb = ByteBuffer.allocate(8);
           bb.putLong(val);
           return bb.array();
       }

4. Given 8 bytes (in big-endian order) containing the two's-complement binary representation of a long, how would you return the long ?

       public static long bytesTolong(byte[] ba) {
           ByteBuffer bb = ByteBuffer.allocate(8);
           bb.put(ba);
           bb.flip();
           return bb.getLong();
       }

5. Given a UUID, how would you return a BigInteger representing the numeric value of the underlying 128-bit ?

       public static BigInteger toBigInteger(UUID uuid) {
           long msb = uuid.getMostSignificantBits();
           long lsb = uuid.getLeastSignificantBits();
           ByteBuffer bb = ByteBuffer.allocate(16);
           bb.putLong(msb).putLong(lsb);
           return new BigInteger(bb.array());
       }

# posted by rot13(Unafba Pune) @ 9:47 PM 0 comments