Java Video Tutorial 2

Up

I want to force the user to type an integer in case of text input but it just stops. I have been stuck in this for 3 days trying to figure out how to go back and make the user retype. I just learnt that there is no goto so I have no idea what to do. Help would be appreciated.

🙂
'…and we're going to type new to get a new scanner object because that's how we get a new scanner object.' Derek says soberly… 'we're always going to this'
paraphrased hilarious
I am a long time Java guy. spent a few years in Kotlin, refresher…

Just wanted to say thanks, Derek. I've been learning Java for about two weeks, have followed some tutorials and I've written a very primitive money tracking app from scratch but I felt like I'd hit a wall with what to do next. I had been on Codecademy and CodeGym and although they're purported to be the best thing since sliced bread, I felt like I was stuck. Your videos are concise and easy to follow and I've learned so much from them already. So again, thank you!

'var.hasNextInt()' has already taken the user input, then how did value 13 reached 'numberEntered' variable (I mean, you need to give second input here?)

I belive this is my first ever comment on youtube and i just want to say you're awsome, hope you're still making videos

can you help me use a text file to get arguments for a method

Derek, first off your teaching is working wonders. I've learned more from you in the past hour from your videos than i have reading text books for a year, thank you for all you do. Also do you think you could do a video over how you create your anki flash cards for programming and programming concepts?? Or maybe even make those decks available for us to download?

python vs java:

java calculator:

import java.util.Scanner;
public class FirstClass{

static Scanner userInput = new Scanner(System.in);
public static void main (String args[]){
int z;
System.out.println("This is a basic calculator");
System.out.println("Enter Your First Number:");

if (userInput.hasNextInt()){

int x = userInput.nextInt();
System.out.println("You entered " +x);
System.out.println("Enter your next number:");
if (userInput.hasNextInt()){
int y = userInput.nextInt();
System.out.println("You entered " + y);
System.out.println("Do you want to Divide(/) Mltiply(mult) add(add) modulus( or subtract(-)");

if (userInput.hasNext("/")){
z = x/y;
System.out.println("The Dividend is " + z);
}
if (userInput.hasNext("mult")){
z = x*y;
System.out.println("The product is " + z);
}
if (userInput.hasNext("add")){
z = x + y;
System.out.println("The sum is " +z);
}

if (userInput.hasNext("-")){
z = x-y;
System.out.println("The difference is " + z);
}
if (userInput.hasNext("%")){
z = x % y;
System.out.println("The remainder is " + z);
}
}

}
else{
System.out.println("error");
}

}
}

python (3.5) calculator:

n1 = int(input("what is your first number"))
op =input ("do you want to / * – + or **")
n2 = int(input ("what is your seccond number?"))
# these are what you want to ask the user
if op== "/":
awncer= n1 / n2
elif op== "*":
awncer = n1 * n2
elif op== "-":
awncer = n1 – n2
elif op== "+":
awncer= n1 + n2
elif op == "**":
awncer= n1 ** n2
#this is how the com. does the math
print(n1, op, n2)
print("this =")
print (awncer)
#this is how you print the awncer and how the com got

//calculator!!!!!!!
import java.util.Scanner;
public class calc{

static Scanner userInput = new Scanner(System.in);
public static void main (String args[]){
int z;
System.out.println("This is a basic calculator");
System.out.println("Enter Your First Number:");

if (userInput.hasNextInt()){

int x = userInput.nextInt();
System.out.println("yo entered " +x);
System.out.println("Enter your next number:");
if (userInput.hasNextInt()){
int y = userInput.nextInt();
System.out.println("You entered " + y);
System.out.println("Do you want to Divide(/) Mltiply(mult) add(add) modulus( or subtract(-)");

if (userInput.hasNext("/")){
z = x/y;
System.out.println("The Dividend is " + z);
}
if (userInput.hasNext("mult")){
z = x*y;
System.out.println("The product is " + z);
}
if (userInput.hasNext("add")){
z = x + y;
System.out.println("The sum is " +z);
}

if (userInput.hasNext("-")){
z = x-y;
System.out.println("The difference is " + z);
}

if (userInput.hasNext("%")){
z = x % y;
System.out.println("The remainder is " + z);
}
}

}
else{
System.out.println("error");
}

}

}

great explanation….i am finally able to code..thank you 🙂

Just a quick question, when u delete static from Scanner class, and just type Scanner userInput = new Scanner (System.in); it's throwing an error, why is it like that? Why do you have to put static for all methods and variables inside the class but not inside the main method? (when you just put scanner inside the main method, it works fine but when i just put scanner outside of that method it's giving me an error) great video, btw!

try {to not crash} catch(Exception ProllySomeNullPointer) {System.out.print("Hey, it happened again");}

Hi Derek, am writing code for password reset. Something is wrong. Need help. import java.util.Scanner;

public class LessonTwo
{
public static void main(String[] args)
{
Scanner input = new Scanner(System.in);
System.out.print("Do you wish to change your password?");
if(input.hasNextBoolean();
{
Boolean trueOrFalse = input.nextBoolean();
System.out.println(trueOrFalse);

}

}

}

Hi Derek, your teaching method is really good. Am a newbie in Java and it helps in understanding.