扫描仪抛出NoSuchElementException [英] Scanner throwing NoSuchElementException
问题描述
我正在尝试创建一个简单的小程序,它将要求一个正整数,并且在它从用户收到一个正int之前不会崩溃或关闭。但是,当我的程序多次使用Scanner调用方法时,我的程序会一直崩溃并报告错误NoSuchElementException。我将使用该程序的基础知识来帮助我正在处理的其他一些事情。这是我当前的代码;
I am trying to create a simple small program that will ask for a positive int and won't crash or close until it has received a positive int from the user. However my program keeps crashing, and reporting the error NoSuchElementException, when it calls the method with Scanner in it more than once. I will be using the fundamentals of this program to help some other things I am working on. Here is my current code;
import java.util.InputMismatchException;
import java.util.Scanner;
public class test2 {
/**
* Test ways to avoid crashes when entering integers
*/
public static void main(String[] args) {
int num = testnum();
System.out.println("Thanks for the " + num + ".");
}
public static int testnum() {
int x = 0;
System.out.println("Please enter a positivie integer;");
x = getnum();
while (x <= 0) {
System.out.println("That was not a positive integer, please enter a positive integer;");
x = getnum();
}
return x;
}
public static int getnum() {
Scanner scan = new Scanner(System.in);
int testint;
try {
testint = scan.nextInt();
} catch (InputMismatchException e) {
scan.close();
return 0;
}
scan.close();
return testint;
}
}
任何帮助都将不胜感激,谢谢:)
Any help would be greatly appreciated, thank you :)
推荐答案
试试这个课程,代码中的注释解释一切。
Try out this class, comments in the code explain it all.
import java.util.Scanner;
public class GetPositiveInteger {
private static Scanner scan = new Scanner(System.in); //scanner variable accessible by the entire class
/*
* main method, starting point
*/
public static void main(String[] args) {
int num = 0; //create an integer
while(num <= 0) //while the integer is less than or equal to 0
num = getPostiveNumber(); //get a new integer
System.out.println("Thanks for the number, " + num); //print it out
}
public static int getPostiveNumber() { //method to get a new integer
System.out.print("Enter a postive number: "); //prompt
try {
return scan.nextInt(); //get the integer
} catch (Exception err) {
return 0; //if it isn't an integer, try again
}
}
}
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