Enabling or disabling a login view based on authentication state Is it good to have this:

if(DataHolder.i().getLoginParamInfo().equals(LoginState.stateLoggingIn)) {
    getView().findViewById(R.id.login_button).setEnabled(true);
}
else {
    getView().findViewById(R.id.login_button).setEnabled(false);
}


or this:

getView().findViewById(R.id.login_button).setEnabled(DataHolder.i().getLoginParamInfo().equals(LoginState.stateLoggingIn));
Short code vs longer code:

Writing shorter code can in certain situations be a good thing. But in your case I would not recommend this as it makes your code hard to read and/or maintain. Try something like this:

//I don't know the return-type of getLoginParamInfo(), hence the "LoginState".
LoginState parameterInfo = DataHolder.i().getLoginParamInfo();
boolean isLoggingIn = parameterInfo.equals(LoginState.stateLoggingIn);
getView().findViewById(R.id.login_button).setEnabled(isLoggingIn);


If you want, you can combine the first two lines into one. This gives following code:

boolean isEqual = DataHolder.i().getLoginParamInfo().equals(LoginState.stateLoggingIn);
getView().findViewById(R.id.login_button).setEnabled(isEqual);


But again, pumping al code in one line is certainly not a good practice.

Method naming:

Giving your functions/methods names like i() is definitly not good practice. It doesn't tell anything about what it does and what it eventually returns.