我正在尝试编写战舰游戏,并且在提示用户输入猜测坐标的位置遇到此错误:
Exception in thread "main" java.util.NoSuchElementException
at java.util.Scanner.throwFor(Unknown Source)
at java.util.Scanner.next(Unknown Source)
at java.util.Scanner.nextInt(Unknown Source)
at java.util.Scanner.nextInt(Unknown Source)
at game.User.takeTurn(User.java:121)
at game.Game.main(Game.java:61)
以下是发生错误的User.takeTurn()方法:
static void takeTurn() {
System.out.println("Yout turn!");
System.out.println("Enter your x guess:");
Scanner scanInput = new Scanner(System.in);
int x;
x = scanInput.nextInt();
System.out.println("You entered "+ x + ", Now enter your y coord:");
int y;
y = scanInput.nextInt();
System.out.println("You entered + " + y);
if(Board.aiBoard[x][y] == 2) {
System.out.println("Hit! You got a hit at: " + x + "," + y);
Board.enemyBoardDisplay[x][y] = 'h';
Board.aiBoard[x][y] = 3;
}
else {
System.out.println("Miss!");
Board.enemyBoardDisplay[x][y] = 'x';
Board.aiBoard[x][y] = 1;
}
scanInput.close();
}
我不确定它是否重要但我还在课堂上使用过另一台扫描仪。如果您需要更多代码来帮助我告诉我们。谢谢!
编辑1: 好吧,即使我执行scanInput.hasNextInt()后它也无法正常工作。我还输入了一个给出x值的else语句,但现在x总是具有else语句给出的值。它甚至要求输入它只是默认为该值。但我不希望它转到默认值我希望用户选择。
编辑2:这是我在主存根中调用代码的地方
while (gameOn == true) {
if (turn == 0) {
User.takeTurn();
Board.sunkCheck();
if (gameOn == false)
break;
}
else if (turn == 1) {
Computer.takeTurn();
Board.sunkCheck();
if (gameOn == false)
break;
}
这是我在同一类中使用扫描仪的地方,因为我现在试图使用扫描仪:
System.out
.println("\n Please enter the first x value for your ship (Note, this will be the first point, from this point the \n"
+ " ship can either go vertically downward or horizontally to the right so please choose the topmost point or leftmost \n"
+ "point to do this. Also, the board is 10x10 but due to java array indexing the coordinates go x 0-9 y 0-9: ");
try {
Scanner coord = new Scanner(System.in);
userX = coord.nextInt();
System.out.println("You entered: " + userX);
System.out.println("Now enter the y coordinate for this point: ");
userY = coord.nextInt();
System.out.println("You entered: " + userY);
System.out
.println("Please choose the direction of your ship. Enter v for verticle or h for horizontal(case sensitive): ");
dir = (char) System.in.read();
coord.close();
}
catch(InputMismatchException e) {
System.out.println("Good job doof, since you tried to troll we did all the values for you!");
userX = 3;
userY = 3;
dir = 'v';
}
答案 0 :(得分:3)
您可能需要检查next
元素,然后Scanner
与scanInput.hasNextInt()
一起使用。
<强>更新强>
如果您使用上述Scanner coord = new Scanner(System.in);
,然后使用Scanner scanInput = new Scanner(System.in);
调用该功能而不关闭coord
Scanner
,那么您将遇到问题。
扫描仪将继续消耗流 - 这可能(将)导致 意想不到的副作用。
您可能想要在使用另一个(here for more ref)之前关闭第一个。
<强>更新强>
当您关闭coord.close()
时,您正在关闭System.in
,当您尝试重新读取它时,它将抛出异常。
您无需在每次需要输入时重新打开流,而是可以创建一次Scanner
并重新使用它。
答案 1 :(得分:1)
因此,在进行输入之前,您应该检查扫描仪是否有一些输入供您使用,如:
if (scanInput.hasNextInt()) {
x = scanInput.nextInt();
}