how to get the error detail

[songsongMr]

all the describe of error is "io.eblock.eos4j.api.exception.ApiException: Internal Service Error" ,how to get the error detail
exp:
try {
Transaction t1 = rpc.transfer("5Ka2MNvrtWfNDueCvt4yBMSoKNMNdnL8bcdv94PkgJhpxvTr3Uo","eosio.token", "eosio.token","lishi12", "12.2821 EOS", "");
}catch(Exception ex) {
ex.printStackTrace();
//"io.eblock.eos4j.api.exception.ApiException: Internal Service Error

	}

[espritblock]

Update code
try{
}catch(ApiException ex){
ex.getError()
}