Trabb Pardo – Knuth - Algorithm in streams Trabb Pardo and Knuth devised this simple procedure as a way to explore the functionality of various languages. The wiki page describes it as:


  The Trabb Pardo–Knuth algorithm is a program introduced by Donald Knuth and Luis Trabb Pardo to illustrate the evolution of computer programming languages.


The algorithm is simple:




ask for 11 numbers to be read into a sequence S
reverse sequence S
for each item in sequence S
    call a function to do an operation
    if result overflows
        alert user
    else
        print result



The standard 'function' is to calculate the following:

$$
    f(x) = \sqrt{|x|} + 5 \times x^3
$$

The limiting factor is traditionally the value 400.0.

Here's the Java 8 code to accomplish the traditional 11 input values:



import java.util.Arrays;
import java.util.Scanner;
import java.util.function.IntToDoubleFunction;
import java.util.stream.IntStream;

public class TPK {

    public static void main(String[] args) {
        try (Scanner scanner = new Scanner(System.in);) {
            int[] values = IntStream.generate(scanner::nextInt).limit(11).toArray();
            int[] reversed = IntStream.range(0, values.length)
                    .map(index -&gt; values[values.length - index - 1]).toArray();
            IntToDoubleFunction function =
                    val -&gt; Math.sqrt(Math.abs(val)) + 5 * val * val * val;
            Arrays.stream(reversed)
                    .mapToDouble(function)
                    .forEach(val -&gt; System.out.println(
                            val &gt; 400.0 ? "TOO LARGE" : String.format("%.5f", val)));
        }
    }

}
Instead of generating an array of \$N\$ elements and then reversing it, I'd find it more natural to push values onto a stack and pop off one by one.

It would seem that the "standard" and "traditional" elements would be good as constants, defined near the top of the file:


the number 11
the function to apply
the limit


So that you can play with them easily without making edits inside the main, unchanging part of the code.

Lastly, you have an unnecessary ; in the try statement.

The ability to unit test would be nice, though in this simple example it might take substantial refactoring and lead to over-engineering, and so might not be worth it. Just a thought anyway.