但跑的候出~可以我看看哪出了?
serverIp = InetAddress.getByName("XXX.XXX.XX.XX");
socket =new Socket(XXX,XXX);
socket.setSoTimeout(1000);
DataOutputStream bw = new DataOutputStream(socket.getOutputStream());
char[] result2={0x00,0x00,0x00,0x11};

for(int i=0;i<result2.length;i++)
{
byte[] d = null;
d[i]=(byte)result2[i];
bw.write(d);
}

[解决办法]
byte[] d = null;
d等于null，你怎么给d[i]赋值？
正确的写法是
serverIp = InetAddress.getByName("XXX.XXX.XX.XX");
socket =new Socket(XXX,XXX);
socket.setSoTimeout(1000);
DataOutputStream bw = new DataOutputStream(socket.getOutputStream());
char[] result2={0x00,0x00,0x00,0x11};
byte[] d = new byte[result2.length];

for(int i=0;i<result2.length;i++)
{
d[i]=(byte)result2[i];
}
bw.write(d);