I'm trying to create a pretty simples program in Java and that problem appears "The operator == is undefined for the argument type(s) boolean, int", which is weird because I'm pretty sure that I can use == to compare integers (Int). If anyone could help it would be awesome!

Scanner scanner = new Scanner(System.in);

    int firstSide, secondSide, thirdSide;
    
    System.out.println("Insert the first side lenght of the triangle: ");
    firstSide = scanner.nextInt();
    System.out.println("Insert the second side lenght of the triangle: ");
    secondSide = scanner.nextInt();
    System.out.println("Insert the third side lenght of the triangle: ");
    thirdSide = scanner.nextInt();
    
    
    if (firstSide   secondSide < thirdSide) {
        System.out.println("That triangle doesn't exist! 1");
        return;
    } else if (firstSide   thirdSide < secondSide) {
        System.out.println("That triangle doesn't exist! 2");
        return;
    } else if (secondSide   thirdSide < firstSide) {
        System.out.println("That triangle doesn't exist! 3");
        return;
    } else {
        System.out.println("Everything is OK!");
    }
    
    // Remember that:
    // An Equilateral triangle is a triangle that has all its sides equal.
    // An Isosceles triangle has 2 equal sides.  
    // A Scalene triangle has all different sides.
    
    ******if (firstSide == secondSide == thirdSide) {
        System.out.println("That's an EQUILATERAL triangle!");
    } else if (firstSide == secondSide) {
        System.out.println("That's an ISOSCELES triangle!");
    } else if (thirdSide == firstSide) {
        System.out.println("That's an ISOSCELES triangle!");
    } else if (secondSide == thirdSide) {
        System.out.println("That's an ISOSCELES triangle!");
    } else {
        System.out.println("That's a SCALENE triangle!");
    }

CodePudding user response：

Replace this condition if (firstSide == secondSide == thirdSide)

by if (firstSide == secondSide && firstSide == thirdSide)

firstSide == secondSide : return a boolean value (true or false)

CodePudding user response：

the nextint method could cause problems sometimes as it does not go to the next line. I'd recommend using nextLine instead and pass the int as a String.