소켓 통신 관련 질문입니다.

Question

class PingCheckThread implements Runnable{

		@Override
		public void run() {
			// TODO Auto-generated method stub
			while(!Thread.currentThread().isInterrupted()){
				try {
					if(device != null){
						for(int i = 0; i < device.size(); i++){
							String info = (String) device.get(i);
							int first = info.indexOf(":");
							int last = info.lastIndexOf(":");
							String ip = info.substring(first, last);
							InetAddress targetIp = 
Inet4Address.getByAddress(ip.getBytes()); /// error!!
							 
							if(targetIp.isReachable(60000)){
								Log.v(TAG, "Connection Ok");
							}else{
								Log.v(TAG, "Connection Fail");
							}
							
						}
					}
					Thread.sleep(60000);
				} catch (Exception e) {
					// TODO Auto-generated catch block
					Log.v(TAG, e.getMessage());
				}
			}
		}
	}

보시다시피 InetAddress 에서 오류가 나는데 null point exception 이 납니다. 

08-26 11:27:34.124: W/dalvikvm(3612): threadid=13: thread exiting with uncaught exception (group=0x2c43b930)

08-26 11:27:35.464: E/AndroidRuntime(3612): FATAL EXCEPTION: Thread-216

08-26 11:27:35.464: E/AndroidRuntime(3612): java.lang.NullPointerException

08-26 11:27:35.464: E/AndroidRuntime(3612): at com.skb.sportscompanion.tv.SportsCompanionTV$PingCheckThread.run(SportsCompanionTV.java:206)

08-26 11:27:35.464: E/AndroidRuntime(3612): at java.lang.Thread.run(Thread.java:856)

 

InetAddress.getByName 이나 getByAddress 만 하면 null point exception 이 나는데 이유를 알고 싶습니다.

퍼미션은 설정 하였습니다.