我有这个问题，如果用户说是，我试图开始游戏，我总是通过调用main（）来做，但我的老师坚持认为有更好的方法。如何在不调用main的情况下启动程序。我假设你必须使用循环，但我不确定如何使用它来解决这个问题。
//import library
import java.io.*;
import java.util.*;
//file name
public class GuessingGame
{
//Main method, throws input and output error.
public static void main (String [] args) throws IOException
{
//inputs for random number and switch statements
Scanner inRn = new Scanner (System.in);
Scanner inSw = new Scanner (System.in);
//variables for the loop, random number, character, counter and input
int guess=0;
int rnd;
int num;
char decision;
//random number generator
Random random = new Random();
rnd = random.nextInt(100) + 1;
//loops the user input for the guess
while (true){
try{
//prompt the user
System.out.println(" Please guess a number between 1-100. Press 0 to give up.");
num = inRn.nextInt();
}
//catches input errors
catch (Exception e){
System.out.println("You can only enter numbers!");
inRn.next();
continue;
}
//if statements
if (num==0)
{
//when user types '0' it ends the program
System.out.println("You gave up after " + guess + " try(s) .... Closing program ...");
System.exit(0);
}
else if (num>rnd)
{
System.out.println("The number is too big!");
guess++;
}
else if (num<rnd)
{
//prints 'too small', adds to counter 'guess'
System.out.println("The number is too small!");
guess++;
}
else
{
//prints correct, adds to counter, dsiplays # of guesses and ends loop
System.out.println("You guessed the right number!!: " + rnd);
guess++;
System.out.print(" # of guesses: " + guess + " -");
//loops the case untill correct input is chosen either 'Y' or 'N'
while(true){
//prompt the user if they want to play again
System.out.println(" Would you like to play again? <Y/N>");
decision = inSw.nextLine().charAt(0);
//switch statements
switch (decision) {
case 'Y':
case 'y':
//calls main, basically restarts the game
GuessingGame.main(args);
break;
case 'N':
case 'n':
System.out.println("Bye!");
//exits the program completely
System.exit(0);
break;
default:
//if incorrect input, this prints
System.out.println("Please enter a Yes or No <Y/N>");
}
}
}
}
}
}
答案 0 :(得分：1)
我记得在编程课上，我的老师告诉我要避免使用while（true）语句。
无论如何，有一个专门为这种行为设计的循环，它被称为do-while loop。在main方法中调用main方法称为递归调用。他们有自己的位置，他们可以做其他循环的工作。
这里的问题是每个方法调用都有它自己的局部变量，当你再次调用main时，它仍会记住上一个游戏的所有结果，以及之前的每个游戏。哪个看起来不是很糟糕，尤其是如果您以后使用该信息。更大的问题是递归循环不能被称为无限次，如for或while循环。为每次调用main存储的局部变量存储在堆栈中。当堆栈填满时，你得到一个StackOverflowError。如果你想看到这种情况，请制作一个像这样的主要方法：
public static void main(String args[])
{
main(args);
}
这是一个do-while循环的例子：
Scanner in = new Scanner(System.in);
char decision;
do{
//game code ...
do{
System.out.print("Do you wish to continue? (y,n): ");
decision = in.nextLine().charAt(0);
}while(!(decision == 'y' || decision == 'n'));
}while(decision == 'y');
一些很酷的递归用法：
答案 1 :(得分：0)
我已将游戏逻辑移至新的play()方法。此方法返回boolean以指示用户是否想要在游戏结束时继续玩游戏。我在do...while方法中使用main循环至少启动一次游戏，然后检查play()方法的返回值以决定是否继续游戏。< / p>
这样程序将优雅地结束，而不会强制它使用System.exit方法退出。它也不会使用在while(true)循环内调用的递归方法，最终会导致StackOverflowError异常。
public static void main(String[] args) throws IOException {
boolean keepPlaying = false;
do {
keepPlaying = play();
} while (keepPlaying);
}
private static boolean play() {
//inputs for random number and switch statements
Scanner inRn = new Scanner(System.in);
Scanner inSw = new Scanner(System.in);
//variables for the loop, random number, character, counter and input
int guess = 0;
int rnd;
int num;
char decision;
//random number generator
Random random = new Random();
rnd = random.nextInt(100) + 1;
//loops the user input for the guess
while (true) {
try {
//prompt the user
System.out.println(" Please guess a number between 1-100. Press 0 to give up.");
num = inRn.nextInt();
} //catches input errors
catch (Exception e) {
System.out.println("You can only enter numbers!");
inRn.next();
continue;
}
//if statements
if (num == 0) {
//when user types '0' it ends the program
System.out.println("You gave up after " + guess + " try(s) .... Closing program ...");
return false;
} else if (num > rnd) {
System.out.println("The number is too big!");
guess++;
} else if (num < rnd) {
//prints 'too small', adds to counter 'guess'
System.out.println("The number is too small!");
guess++;
} else {
//prints correct, adds to counter, dsiplays # of guesses and ends loop
System.out.println("You guessed the right number!!: " + rnd);
guess++;
System.out.print(" # of guesses: " + guess + " -");
//loops the case untill correct input is chosen either 'Y' or 'N'
while (true) {
//prompt the user if they want to play again
System.out.println(" Would you like to play again? <Y/N>");
decision = inSw.nextLine().charAt(0);
//switch statements
switch (decision) {
case 'Y':
case 'y':
// User wants to keep playing
return true;
case 'N':
case 'n':
System.out.println("Bye!");
//exits the program completely
return false;
default:
//if incorrect input, this prints
System.out.println("Please enter a Yes or No <Y/N>");
}
}
}
}
}
答案 2 :(得分：0)
你的老师没错，你不必再打电话给主人，只需要增强你的算法，你就会得到更好的代码。也许是这样的：
//import library
import java.io.IOException;
import java.util.Random;
import java.util.Scanner;
//file name
public class GuessingGame {
// Main method, throws input and output error.
public static void main(String[] args) throws IOException {
// inputs for random number and switch statements
Scanner inRn = new Scanner(System.in);
Scanner inSw = new Scanner(System.in);
// variables for the loop, random number, character, counter and input
int guess = 0;
int rnd;
int num = -1;
char decision = 'Y';
// random number generator
Random random = new Random();
rnd = random.nextInt(100) + 1;
// loops the user input for the guess
do {
if (num != rnd) {
try {
// prompt the user
System.out
.println(" Please guess a number between 1-100. Press 0 to give up.");
num = inRn.nextInt();
}
// catches input errors
catch (Exception e) {
System.out.println("You can only enter numbers!");
inRn.next();
continue;
}
// if statements
if (num == 0) {
// when user types '0' it ends the program
System.out.println("You gave up after " + guess
+ " try(s) .... Closing program ...");
System.exit(0);
} else if (num > rnd) {
System.out.println("The number is too big!");
guess++;
} else if (num < rnd) {
// prints 'too small', adds to counter 'guess'
System.out.println("The number is too small!");
guess++;
} else {
// prints correct, adds to counter, dsiplays # of guesses and
// ends loop
System.out.println("You guessed the right number!!: " + rnd);
guess++;
System.out.print(" # of guesses: " + guess + " -");
}
} else {
// prompt the user if they want to play again
System.out.println(" Would you like to play again? <Y/N>");
decision = inSw.nextLine().charAt(0);
// switch statements
switch (decision) {
case 'N':
case 'n':
System.out.println("Bye!");
// exits the program completely
System.exit(0);
break;
case 'Y':
case 'y':
rnd = random.nextInt(100) + 1;
break;
default:
// if incorrect input, this prints
System.out.println("Please enter a Yes or No <Y/N>");
}
}
} while (decision != 'N' || decision != 'n');
inRn.close();
inSw.close();
}
}
为什么这段代码要好得多，恕我直言，因为这些：
希望这会照亮你的一天，如果有任何错误，我很抱歉。谢谢＆amp;问候。