我正在测试我的用户输入，以查看它是否有效。如果无效，则应抛出IllegalArgumentException。但是，无论我的输入是什么，gameLogic函数前几行中的IllegalArgumentException都会被抛出。结果是程序打印"You're only permitted to enter Rock, Paper, Scissors or -1 in this game."无论我的输入是什么。
import java.util.Scanner;
import java.util.Random;
class RockPaperScissors
{
private static double mUserWinCount = 0;
private static double mCpuWinCount = 0;
private static double mUserLossCount = 0;
private static double mCpuLossCount = 0;
private static double mDrawCount = 0;
private static double mGameCount = 0;
private static String mCpuInput;
private static String mUserInput;
public static void main(String [] args)
{
try
{
gameLogic(cpuInput(),userInput());
}
catch(IllegalArgumentException iae)
{
System.out.println(iae.getMessage());
}
}
static String cpuInput()
{
Random random = new Random (System.currentTimeMillis());
int RandomNumber=random.nextInt(3);
if (RandomNumber == 0)
mCpuInput = "Rock";
else if (RandomNumber == 1)
mCpuInput = "Paper";
else
mCpuInput = "Scissors";
return mCpuInput;
}
static String userInput()
{
System.out.println("Enter Rock, Paper or Scissors, enter -1 in order to exit:- ");
mUserInput = new Scanner(System.in).next();
return mUserInput;
}
static void gameLogic(String cpuInput, String userInput)
{
if(!userInput.equalsIgnoreCase("Rock") || !userInput.equalsIgnoreCase("Paper") || !userInput.equalsIgnoreCase("Scissors") || !userInput.equals("-1"))
{
throw new IllegalArgumentException("You're only permitted to enter Rock, Paper, Scissors or -1 in this game.n");
}
if(userInput.equals("-1"))
{
score();
System.exit(0);
}
System.out.println("CPU entered "+cpuInput+", User entered "+userInput);
String [] args = new String[0];
if(userInput.equalsIgnoreCase(cpuInput))
{
System.out.println("It's a draw!");
mDrawCount++;
mGameCount++;
}
if(userInput.equalsIgnoreCase("Rock") && cpuInput.equalsIgnoreCase("Scissors") || userInput.equalsIgnoreCase("Paper") && cpuInput.equalsIgnoreCase("Rock") || userInput.equalsIgnoreCase("Scissors") && cpuInput.equalsIgnoreCase("Paper"))
{
System.out.println("User wins!");
mUserWinCount++;
mCpuLossCount++;
mGameCount++;
}
if(cpuInput.equalsIgnoreCase("Rock") && userInput.equalsIgnoreCase("Scissors") || cpuInput.equalsIgnoreCase("Paper") && userInput.equalsIgnoreCase("Rock") || cpuInput.equalsIgnoreCase("Scissors") && userInput.equalsIgnoreCase("Paper"))
{
System.out.println("CPU wins!");
mCpuWinCount++;
mUserLossCount++;
mGameCount++;
}
main(args);
}
static void score()
{
if (mGameCount==0)
{
System.out.println("No games have been played..");
}
else
{
double userWinPercentage = (mUserWinCount / mGameCount) * 100;
double userLossPercentage = (mUserLossCount / mGameCount) * 100;
double cpuWinPercentage = (mCpuWinCount / mGameCount) * 100;
double cpuLossPercentage = (mCpuLossCount / mGameCount) * 100;
double drawPercentage = (mDrawCount/mGameCount) * 100;
System.out.println("Number of Games Played- " + mGameCount);
System.out.println("Number of Draws- "+ mDrawCount);
System.out.println("Percentage of Draws "+ drawPercentage + "%");
System.out.println("Number of Wins by User- " + mUserWinCount);
System.out.println("User's Win Percentage- " + userWinPercentage + "%");
System.out.println("Number of Losses by User- " + mCpuLossCount);
System.out.println("User's Loss Percentage- " + userLossPercentage + "%");
System.out.println("Number of Wins by CPU- " + mCpuWinCount);
System.out.println("CPU's Win Percentage- " + cpuWinPercentage + "%");
System.out.println("Number of Losses by CPU- " + mCpuLossCount);
System.out.println("CPU's Loss Percentage- " + cpuLossPercentage + "%");
}
}
在这一行中
if(!userInput.equalsIgnoreCase("Rock") || !userInput.equalsIgnoreCase("Paper") || !userInput.equalsIgnoreCase("Scissors") || !userInput.equals("-1"))
使用&&，而不是||†
if(!userInput.equalsIgnoreCase("Rock") && !userInput.equalsIgnoreCase("Paper") && !userInput.equalsIgnoreCase("Scissors") && !userInput.equals("-1"))
您可以使用真值表的形式来了解原因：
| Input | A | B | C | D | || Result | && Result |
|------------+---+---+---+---+-----------|-----------|
| "Rock" | F | T | T | T | T | F |
| "Paper" | T | F | T | T | T | F |
| "Scissors" | T | T | F | T | T | F |
| "-1" | T | T | T | F | T | F |
| "foo" | T | T | T | T | T | T |
†但是，从设计的角度来看，您可能希望重新构建代码，以要求用户在输入不正确时重复输入，而不仅仅是在异常的情况下终止游戏。
if(!userInput.equalsIgnoreCase("Rock") || !userInput.equalsIgnoreCase("Paper")
这句话总是正确的。我们有三种可能性：
- 这个词既不是"岩石"也不是"纸"(忽略大小写(
- 这个词是"摇滚">
- 这个词是"纸">
如果 a(，两个 equalIgnoreCase 都将返回 false，那么你用 ！你得到真的 ||真 ( == 真，显然 (
如果 b( 你得到假 ||真 ( == 真(
如果 c( 你得到 TRUE ||假 ( == 真(
我将展示一段重构的代码，向您展示处理输入和主循环的替代方法。
此代码对输入进行显式检查，在确保输入为小写后对输入使用switch。请注意，检查正确的用户输入应放在游戏逻辑之外。你的游戏逻辑应该是：执行游戏的代码。如果您有两个 CPU 播放器怎么办？
除此之外，它还包含许多编码提示，从NOTE：开始。
import java.util.Scanner;
import java.util.Random;
class RockPaperScissors {
// NOTE: prefer integers instead of doubles for counts
private static int mUserWinCount = 0;
private static int mCpuWinCount = 0;
// NOTE: avoid double state
// isn't user loss always identical to cpu win count?
private static int mUserLossCount = 0;
private static int mCpuLossCount = 0;
private static int mDrawCount = 0;
private static int mGameCount = 0;
public static void main(String[] args) {
// NOTE: always manage your resources
try (Scanner scanner = new Scanner(System.in)) {
// NOTE: never use recursion unless you cannot avoid it
// prefer while loop over calling main)
while (true) {
String userInput = userInput(scanner);
if (userInput.equals("-1")) {
score();
// NOTE: prefer running out of main over calling exit
break;
}
// NOTE: bring back the amount of state ASAP!
// just lowercase has less state, enums have even less
if (!validChoice(userInput)) {
System.out.println("Not a valid choice!");
continue;
}
try {
String cpuInput = cpuInput();
gameLogic(cpuInput, userInput);
} catch (IllegalArgumentException iae) {
System.out.println(iae.getMessage());
}
}
}
}
// NOTE: use explicit checks for user input
static boolean validChoice(String userChoice) {
switch (userChoice.toLowerCase()) {
case "paper":
case "scissors":
case "rock":
return true;
default:
return false;
}
}
static String cpuInput() {
// NOTE: only define your variables in the scope where they are needed
// this doesn't need to be a field
String mCpuInput;
// NOTE: prefer new SecureRandom() over Random if performance is not
// essential
Random random = new Random(System.currentTimeMillis());
int RandomNumber = random.nextInt(3);
if (RandomNumber == 0)
mCpuInput = "Rock";
else if (RandomNumber == 1)
mCpuInput = "Paper";
else
mCpuInput = "Scissors";
return mCpuInput;
}
static String userInput(Scanner scanner) {
String mUserInput;
System.out
.println("Enter Rock, Paper or Scissors, enter -1 in order to exit:- ");
mUserInput = scanner.next();
return mUserInput;
}
static void gameLogic(String cpuInput, String userInput) {
// NOTE: use logging instead for debug statements
System.out.println("CPU entered " + cpuInput + ", User entered "
+ userInput);
// NOTE: learn to detect code smell...
// if you don't really need args you should not have to define it
// String [] args = new String[0];
if (userInput.equalsIgnoreCase(cpuInput)) {
// NOTE: don't mix input/output with the actual game rules
// return the outcome and then print instead (not fixed)
System.out.println("It's a draw!");
mDrawCount++;
mGameCount++;
}
if (userInput.equalsIgnoreCase("Rock")
&& cpuInput.equalsIgnoreCase("Scissors")
|| userInput.equalsIgnoreCase("Paper")
&& cpuInput.equalsIgnoreCase("Rock")
|| userInput.equalsIgnoreCase("Scissors")
&& cpuInput.equalsIgnoreCase("Paper")) {
System.out.println("User wins!");
mUserWinCount++;
mCpuLossCount++;
mGameCount++;
}
if (cpuInput.equalsIgnoreCase("Rock")
&& userInput.equalsIgnoreCase("Scissors")
|| cpuInput.equalsIgnoreCase("Paper")
&& userInput.equalsIgnoreCase("Rock")
|| cpuInput.equalsIgnoreCase("Scissors")
&& userInput.equalsIgnoreCase("Paper")) {
System.out.println("CPU wins!");
mCpuWinCount++;
mUserLossCount++;
mGameCount++;
}
// NOTE: avoid recursion
// don't do this, if you do *document*
// main(args);
}
static void score() {
if (mGameCount == 0) {
System.out.println("No games have been played..");
} else {
double userWinPercentage = (mUserWinCount / mGameCount) * 100;
double userLossPercentage = (mUserLossCount / mGameCount) * 100;
double cpuWinPercentage = (mCpuWinCount / mGameCount) * 100;
double cpuLossPercentage = (mCpuLossCount / mGameCount) * 100;
double drawPercentage = (mDrawCount / mGameCount) * 100;
// NOTE: learn about printf when the time comes
System.out.println("Number of Games Played- " + mGameCount);
System.out.println("Number of Draws- " + mDrawCount);
System.out.println("Percentage of Draws " + drawPercentage + "%");
System.out.println("Number of Wins by User- " + mUserWinCount);
System.out.println("User's Win Percentage- " + userWinPercentage
+ "%");
System.out.println("Number of Losses by User- " + mCpuLossCount);
System.out.println("User's Loss Percentage- " + userLossPercentage
+ "%");
System.out.println("Number of Wins by CPU- " + mCpuWinCount);
System.out.println("CPU's Win Percentage- " + cpuWinPercentage
+ "%");
System.out.println("Number of Losses by CPU- " + mCpuLossCount);
System.out.println("CPU's Loss Percentage- " + cpuLossPercentage
+ "%");
}
}
}
快乐编码。