if Statement on two user inputs

Question

import java.util.Scanner;

public class RunBloodData {

public static void main (String [] args){

Scanner sc = new Scanner(System.in);

System.out.println("Enter blood type of patient:");

String input1 = sc.nextLine();

System.out.println("Enter the Rhesus facator (+ or -):");

String input2 = sc.nextLine();

BloodData bd = new BloodData(input1, input2);

BloodData dbd = new BloodData();

if (){

bd.display();

}

else {

dbd.display();

}

class BloodData{

static String bloodType;

static String rhFactor;

public BloodData(){

bloodType = "O";

rhFactor = "+";

}

public BloodData(String bt, String rh){

this.bloodType = bt;

this.rhFactor = rh;

}

public void display(){

System.out.println(bloodType + rhFactor + "is added to the blood bank");

}

}

I have trouble regarding the if statement on what should I use to run it. I want to be able to use the if statement if the user has put an input it will print out the inputs, but if the user has not put any input, it will only print out the default variables that I have put. But I do not know how to use the if statement regarding multiple user inputs and strings. so I would like to ask on what should I put on the () in the if statement or whether I should use a different statement. Thank you

Answer 1

If I understand your question correctly, you are asking how to print bd.display() only if the user has put input into input1 and input2, but to print dbd.display() if there is no input for either input1 or input2.

The first problem I notice is that your variables are static, this means that every time you make a new BloodData object, those variables are changed to whatever the new value is. In other words, when constructing dbd, you delete whatever input1 and input2 were. Because of this, no matter what you put in your if, it will always look like it is calling dbd.display() even if it isn't. If you get rid of the static keyword on your variables, your if could look something like this:

BloodData bd = new BloodData(input1, input2);

BloodData dbd = new BloodData();

if (!input1.equals("") && !input2.equals("")) {

bd.display();

} else {

dbd.display();

}

If that is intentional and I just don't understand why, you could move the dbd construction inside the else, so that the values aren't rewritten. Then, your if would look something like:

BloodData bd = new BloodData(input1, input2);

if (!input1.equals("") && !input2.equals("")) {

bd.display();

} else {

new BloodData().display();

}

I hope that answers your question.