Why is 0 not equal to 0?

Question

Java

import java.util.Scanner;

public class Main {
public static void main(String[] args) {
    
Scanner sc = new Scanner(System.in);

String a = "";

System.out.println("Какие будут игроки?");
System.out.println();

System.out.println("1 - Добавить игрока");
System.out.println("0 - Закончить добавлять игроков");
System.out.println();

Boolean g=true;

while (g){
  a = sc.nextLine();
  if (a == "0"){
    System.out.println("Конец");
    g = false;
  }
  
  else if (a == "1"){
    System.out.println("Продолжаем");
    g = false;
  }
    
  else {
    System.out.println("Некорректно введено число!");	
  } 
}

}

Answer 1

Strings created at compile time end up in the StringPool, so they can be compared using '==' since they are essentially the same object. Strings created at Runtime do not get into the StringPool, so a new object is always created, therefore, as mentioned above, to get the correct result, you need to use Equals.

Answer 2

Why, why... because someone missed the lecture on object comparison.