How to check if there is a next marker using Scanner.hasNext() method in Java?

How to check if there is a next marker using Scanner.hasNext() method in Java?

The Scanner class is a class commonly used in Java for user input data. It can read standard input, files, etc. very conveniently. When using the Scanner class, you often need to check whether the input meets expectations. In this case, you can use the Scanner's hasNext() method.

The hasNext() method of the Scanner class is used to check whether there is a next token in the current input, and its return value is of boolean type. When there is a next token in the input, the hasNext() method returns true; when the input has ended and there is no next token, it returns false.

The following is a specific code example of using the Scanner.hasNext() method to check whether there is a next token:

import java.util.Scanner;

public class ScannerExample {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入一个整数：");

        if (scanner.hasNextInt()) {
            int num = scanner.nextInt();
            System.out.println("你输入的整数是：" + num);
        } else {
            System.out.println("输入错误，请输入一个整数！");
        }

        scanner.close();
    }
}

In the above example, we use the Scanner class to read the integer entered by the user. First, we create a Scanner object and pass System.in as parameter to read data from standard input.

Next, we use the hasNextInt() method to check whether the input is an integer. If the input is an integer, we read the integer through the nextInt() method, store it in the num variable, and print it out. If the input is not an integer, we prompt the user for an input error.

Finally, we call the Scanner's close() method to close the Scanner object.

Through the use of the above code, we can easily use the Scanner.hasNext() method to check whether the input meets expectations and process it according to the situation. This is very useful when handling user input, and can effectively avoid errors caused by unexpected input.

To summarize, the Scanner.hasNext() method is a method in Java used to check whether there is a next mark in the input. This method can easily determine whether the input meets expectations and perform corresponding processing. . I hope that through the introduction of this article, readers can better use the Scanner class for input processing.

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