The Riddle of Java--a speech from Neal Gafter __java

Translation staff: Anchor

Translation Date: November 20, 2013

Source text link: A puzzle from "a Brief History of the (Java) world and A Peek Forward" presented by Neal Gafter

Here's a Java riddle from Neal Gafter's speech:

Import Java.util.Random;
Rhymes, rhyme public
class Rhymes {
    private static Random rnd = new Random ();
    /**
     * What could be the output of the following program?
     * (a) Pain, Gain or main (according to each random number)
     * (b) Pain or main (according to random number)
     * (c) Main (always this)
     * (d) None of the above is not
    * * * public static void Main (string[] args) {
        StringBuffer word = null;
        Switch (Rnd.nextint (2)) {case
        1:word = new StringBuffer (' P ');
        Case 2:word = new StringBuffer (' G ');
        Default:word = new StringBuffer (' M ');
        }
        Word.append (' a ');
        Word.append (' i ');
        Word.append (' n ');
        SYSTEM.OUT.PRINTLN (Word);
    }

Which is the correct answer?

The correct answer is D.
There are three flaws in the program:

1. Obviously, there is no break in the switch statement

2. Nextint (2) The result returned is only 0 or 1

3. ' P ', ' G ', ' M ' is a char-type hand, not a string object, so it is automatically converted to an int and a constructor that does not conform to the expected function is invoked.

For more information, refer to the books of Joshua Bloch and Columbia (Neal gafter), "Java FAQ"

Related reading:

Ten common Java string issues
Declaration, initialization and scoping for Java Java Code:given range, return an array of N random numbers constructor C An Throw exceptions in java!