Triangle calculator: calculate if it's a valid triangle and what type
Bug
Your code assumes that the user will enter the longest side last! This is a bug. Id the user enters the values 10, 1, and 1, it will declare that it is a triangle because 10 + 1 &gt; 1
Functions!
Where are your functions?
One of the best ways to document your code, and make sense of it, is to have well-named functions. Your function is main, and.... well, that does not do a good job of telling us what the function does.
What you need is a function called something like boolean isValidTriangle(int sideA, int sideB, int sideC), then make that function &quot;work&quot;.
A valid triangle is one whose shorter sides add up to more than the longest side, right? The trick is finding the longest side.... In this case, recursion is a trick that can help....
boolean isValidTriangle(int sideA, int sideB, int sideC) {

    // recursion trick, make sure sideA is the longest side!

    if (sideA &lt; sideB) {
        // call the function with sideB first
        return isValidTriangle(sideB, sideA, sideC)
    }

    if (sideA &lt; sideC) {
        // call the function wwith sideC first
        return isValidTriange(sideC, sideB, sideA)
    }
    
    // OK, sideA is the longest, for sure!
    return sideA &lt;= sideB + sideC

}

Similarly, you can do the same sort of thing to classify the triangle types.