How to increment a counter each time a variable is added to the map ?

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I'm trying to create a note-taking app that gives every note an incremented number starting from 1, my question is how to increment the "count" variable in "addNote()" method so it's get increased every time an entry is put inside the map and give each entry a number bigger by one than the previous number?

Java

public class Main {
    static Scanner scanner = new Scanner(System.in);
    static Map<Integer,String> myNotes = new HashMap<>();

    public static void main(String[] args) {
        
    }

    public static boolean addNote() {
        System.out.println("Enter a note to added ");
        String note = scanner.nextLine();
        if (myNotes.containsValue(note)) {
            System.out.println("Note " + note + " already exists");
            return false;
        }
        int count=1;
        myNotes.put(count,note);
        System.out.println("Note added successfully");
        return true;
    }

What I have tried:

i didn't know what to do, i tried some ways but it didn't worked.

Posted 22-Jun-19 22:54pm

hiwa doski

Updated 22-Jun-19 23:13pm

Afzaal Ahmad Zeeshan

v3

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Afzaal Ahmad Zeeshan · Accepted Answer · 2019-06-22T23:07:00

Take your count variable outside the function—because of the scoping in Java, that variable gets deleted and refreshed as 1 each time you call the function to add the note, which then leads to update of the value for that key, which is 1.

Java

static int count = 1; // needs to be static to be accessible in static context.

public static boolean addNote() {
    System.out.println("Enter a note to added ");
    String note = scanner.nextLine();
    if (myNotes.containsValue(note)) {
        System.out.println("Note " + note + " already exists");
        return false;
    }

    // use the current value, but update for next call!
    myNotes.put(count++, note); 
    System.out.println("Note added successfully");
    return true;
}

Now this will work as you are expecting it to. Now in the main you can call the function multiple times.

Please check these links for more on this topic,
Interesting facts about Increment and Decrement operators in Java - GeeksforGeeks[^]
Scope of Variables In Java - GeeksforGeeks[^]