Need basic help with methods.

[vague wave]

I am new to java, cant understand why is it showing java: <identifier> expected and not working.

[iron summit]

<@&987246399047479336> please have a look, thanks.

[iron summit]

While you are waiting for getting help, here are some tips to improve your experience:

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[vague wave]

import java.util.Scanner;
public class RomanToInteger {
    public String romanToInt(input) {


        int total = 0;

        for (int i = 0; i < input.length(); i++) {
            char number = input.charAt(i);
            switch (number) {
                case 'I' -> total += 1;
                case 'V' -> total += 5;
                case 'X' -> total += 10;
                case 'L' -> total += 50;
                case 'C' -> total += 100;
                case 'D' -> total += 500;
                case 'M' -> total += 1000;
                default -> System.out.printf("%s is not a valid roman number, Ignored it  \n", number);
            }

        }
        System.out.println("The total is " + total);
    }

    public static void main (String[] args) {
        System.out.print("Enter a roman number: ");
        Scanner sc = new Scanner(System.in);
        String input = sc.nextLine();

        romanToInteger(input);
    }
}```

[iron summit]

Detected code, here are some useful tools:

Formatted code

import java.util.Scanner;

public class RomanToInteger {
  public String romanToInt(input) {
    int total = 0;
    for (int i = 0; i < input.length(); i++) {
      char number = input.charAt(i);
      switch (number) {
        case 'I' -> total += 1;
        case 'V' -> total += 5;
        case 'X' -> total += 10;
        case 'L' -> total += 50;
        case 'C' -> total += 100;
        case 'D' -> total += 500;
        case 'M' -> total += 1000;
        default  -> System.out.printf("%s is not a valid roman number, Ignored it  \n", number);
      }
    }
    System.out.println("The total is " + total);
  }
  public static void main(String[] args) {
    System.out.print("Enter a roman number: ");
    Scanner sc = new Scanner(System.in);
    String input = sc.nextLine();
    romanToInteger(input);
  }
}

[broken mirage]

your method is romanToInt
you are calling it as romanToInteger

ah, also, input does not have a type in your method declaration

change it to String input in your method declaration

[vague wave]

What do you mean by type ?

[vague wave]

Oh yeaa

Error:

java: non-static method romanToInt(java.lang.String) cannot be referenced from a static context```

```java
import java.util.Scanner;
public class RomanToInteger {
    public String romanToInt(String input) {


        int total = 0;

        for (int i = 0; i < input.length(); i++) {
            char number = input.charAt(i);
            switch (number) {
                case 'I' -> total += 1;
                case 'V' -> total += 5;
                case 'X' -> total += 10;
                case 'L' -> total += 50;
                case 'C' -> total += 100;
                case 'D' -> total += 500;
                case 'M' -> total += 1000;
                default -> System.out.printf("%s is not a valid roman number, Ignored it  \n", number);
            }

        }
        System.out.println("The total is " + total);
    }

    public static void main (String[] args) {
        System.out.print("Enter a roman number: ");
        Scanner sc = new Scanner(System.in);
        String input = sc.nextLine();

        romanToInt(input);
    }
}```

[broken mirage]

String, int, boolean, float, double, your classes, others classes, etc.

[broken mirage]

put a static keyword after public in your romanToInt

[vague wave]

Okay sir, thank you

[broken mirage]

basically:

static is a form of context

non-static means: attached to objects (variables which creates your classes with new)
static means: you don't need to create a object for using this function, instead, this method is attached to the class signature

[vague wave]

ohk understood

Now it says java: incompatible types: int cannot be converted to java.lang.String

[broken mirage]

you are not returning anything in romanToInt

[broken mirage]

hmm

yeah, total is an int, while you are saying the function returns String

[vague wave]

In Line3 dosent string tell it that input is a String?

[broken mirage]

*String* romanToInt(...)

[vague wave]

ohk that one

So I should just change it to int keyword right?

[broken mirage]

yes

[vague wave]

One more error 🫠

java: cannot find symbol
 symbol:   variable total
 location: class RomanToInteger```

[broken mirage]

int total = romanToInt(input);

in main method

[vague wave]

Okay yea works now finally

Thank you so much sir

[broken mirage]

:D

[still zenith]

W

[vague wave]

After Python, learning Java is just depressing

[broken mirage]

I see, you didn't "typed" input when I came here, so I thought: Ohh, python dev

[vague wave]

ye lol

Since past 2 hours I was stuck on this one RomanToInteger program

Any good source to learn Java effectively?

[iron summit]

MOOC is a completely free introductory Java course created by the University of Helsinki, it is a great way to learn Java from the ground up.

It consists of two parts, one at beginner, and another at intermediate level. The end of the course is marked by creating your own Asteroids game clone!

Even though the instructions show how to configure and use NetBeans for the course, you can use IntelliJ. To use IntelliJ, simply install the TMC plugin by opening IntelliJ -> File -> Settings -> Plugins and searching for TMC. You will then be able to use IntelliJ to complete MOOC.

Visit MOOC here: https://java-programming.mooc.fi/
(the course is available in both English and Finnish)

Renan Kogan • used /tag id: mooc · Feb 14, 2023, 2:23 AM

About the course - Java Programming

About the course - Java Programming

[vague wave]

Okay tysm!