我正在进行一项课程作业，我必须使用递归代码从列表中取出不同的单词并制定句子。在大多数情况下，我的代码部分工作，但问题是，它不会停止。我将在下面发布我的代码，非常感谢任何指针或解决方案。
/*
* A program that implements BNF rules to generate random sentences.
*
* The program generates and outputs one random sentence every three
* seconds until it is halted (for example, by typing Control-C in the
* terminal window where it is running).
*
* The rules that this program follows are:
*
* <sentence> ::= <simple_sentence> [ <conjunction> <sentence> ]
*
* <simple_sentence> ::= this is a <adjective> project <conjunction>
* <noun_phrase> <verb_phrase>
*
* <noun_phrase> ::= <proper_noun> |
* <determiner> [ <adjective> ]. <common_noun> [ who <verb_phrase> ]
*
* <verb_phrase> ::= <intransitive_verb> |
* <transitive_verb> <noun_phrase> |
* is <adjective> |
* believes that <simple_sentence>
*
* Rules for nouns, verbs, conjunctions, etc. are implemented by arrays.
*/
package randomrecursion;
import java.util.Random;
/**
*
* @author Xavier
*/
public class RandomRecursion {
// Implement arrays for last seven rules in the list.
private static final String[] conjunctions = { "and", "or", "but",
"because", "since", "when" };
private static final String[] properNouns = { "Fred", "Jane",
"Richard Nixon", "Miss America", "Berry White", "Jeff Dunham" };
private static final String[] commonNouns = { "man", "woman", "fish",
"elephant", "ball", "planet", "model", "stunt-man" };
private static final String[] determiners = { "a", "the", "every", "some",
"each", "neither", "either" };
private static final String[] adjectives = { "big", "tiny", "pretty",
"bald", "odd", "scary", "unfortunate", "nice", "rediculus", "carefree" };
private static final String[] intransitiveVerbs = { "runs", "jumps",
"talks", "sleeps", "eats", "cries", "laughs" };
private static final String[] transitiveVerbs = { "loves", "hates", "sees",
"knows", "lives", "hunts", "accepts", "cleans" };
// Instantiate a Random() object.
private static final Random rGen = new Random();
/*
* rGen will be used by chanceToBeTrue to select a double in the
* range 0-1. If the value is less than SMALL_CHANCE,
* chanceToBeTrue(SMALL_CHANCE) returns true.
* MEDIUM_CHANCE and LARGE_CHANCE work in the same way.
* 0.1 is equivalent to a 10% chance.
*/
private static final double SMALL_CHANCE = 0.1;
private static final double MEDIUM_CHANCE = 0.5;
private static final double LARGE_CHANCE = 0.75;
/*
* Values will be added together and used with if/else statements
* to determine probabilities for branches in the verbPhrase()
* routine. 0.1 is equivalent to a 10% chance.
*/
private static final double CHANCE_FOR_INTRANSITIVE = 0.4;
private static final double CHANCE_FOR_TRANSITIVE = 0.1;
private static final double CHANCE_FOR_ADJECTIVE = 0.4;
private static final int MILLISECONDS_TO_SLEEP = 2000;
/**
* This routine calls the randomSentence routine to generate random
* sentences in a loop, pausing for MILLISECONDS_TO_SLEEP in
* between each sentence.
*
* @param args Command line args (not used).
*/
public static void main(String[] args) {
while (true) {
randomSentence();
System.out.println(".\n\n");
try {
Thread.sleep(MILLISECONDS_TO_SLEEP);
} catch (InterruptedException e) {
}
}
}
/**
* This routine creates one random sentence following this rule:
*
* <sentence> ::= <simple_sentence> [ <conjunction> <sentence> ]
*/
private static void randomSentence() {
simpleSentence();
if (chanceToBeTrue(SMALL_CHANCE)) {
randomItem(conjunctions);
System.out.print(" ");
randomSentence();
}
}
/**
* This routine creates a simple sentence following this rule:
*
* <simple_sentence> ::= this is a <adjective> project <conjunction>
* <noun_phrase> <verb_phrase>
*/
private static void simpleSentence() {
makeItInteresting();
nounPhrase();
verbPhrase();
}
/**
* This routine adds an interesting beginning to each simpleSentence.
*/
private static void makeItInteresting() {
System.out.print("this is a");
randomItem(adjectives);
System.out.print(" project");
randomItem(conjunctions);
}
/**
* This routine creates a noun phrase following this rule:
*
* <noun_phrase> ::= <proper_noun> |
* <determiner> [ <adjective> ] <common_noun> [ who <verb_phrase> ]
*/
private static void nounPhrase() {
if (chanceToBeTrue(MEDIUM_CHANCE)) {
randomItem(properNouns);
} else {
randomItem(determiners);
if (chanceToBeTrue(LARGE_CHANCE)) {
randomItem(adjectives);
}
randomItem(commonNouns);
if (chanceToBeTrue(SMALL_CHANCE)) {
System.out.print(" who");
verbPhrase();
}
}
}
/**
* This routine creates a verb phrase following this rule:
*
* <verb_phrase> ::= <intransitive_verb> |
* <transitive_verb> <noun_phrase> |
* is <adjective> |
* believes that <simple_sentence>
*/
private static void verbPhrase() {
// Instantiate a random double between 0.0 (inclusive)
// and 0.1 (exclusive).
double chance = rGen.nextDouble();
if (chance < CHANCE_FOR_INTRANSITIVE) {
randomItem(intransitiveVerbs);
} else if (chance < (CHANCE_FOR_INTRANSITIVE + CHANCE_FOR_TRANSITIVE)) {
randomItem(transitiveVerbs);
nounPhrase();
} else if (chance < (CHANCE_FOR_INTRANSITIVE
+ CHANCE_FOR_TRANSITIVE + CHANCE_FOR_ADJECTIVE)) {
System.out.print(" is");
randomItem(adjectives);
} else {
System.out.print(" believes that ");
simpleSentence();
}
}
/**
* This routine randomly chooses an item from an array of strings.
*/
private static void randomItem(String[] listOfStrings) {
/*
* Get next integer from rGen that is between 0 (inclusive) and
* listOfStrings.length (exclusive) and print that randomly chosen
* element of the list of Strings.
*/
int choice = rGen.nextInt(listOfStrings.length);
System.out.print(" " + listOfStrings[choice]);
}
/**
* This routine uses rGen to return true percentChance amount
* of the time.
*
* @param percentChance double value between 0.0 (inclusive)
* and 1.0 (exclusive).
* @return true if a randomly chosen double value
* is less than percentChance.
*/
private static boolean chanceToBeTrue(double percentChance) {
double number = rGen.nextDouble();
if (number < percentChance) {
return true;
} else {
return false;
}
}
}
答案 0 :(得分：1)
由于while-loop
main，它不会停止
while (true) {
randomSentence();
System.out.println(".\n\n");
try {
Thread.sleep(MILLISECONDS_TO_SLEEP);
} catch (InterruptedException e) {
}
}
不是因为递归。