Java uses the nextInt() function of the Scanner class to obtain the integer value entered by the console

Java uses the nextInt() function of the Scanner class to obtain the integer value of the console input

The Scanner class is one of the classes commonly used in Java to accept console input. It provides many convenient methods, including the nextInt() function, which is used to obtain the integer value of the console input. This article will use a code example to introduce how to use the nextInt() function of the Scanner class to obtain the integer value input by the console.

First, we need to introduce the java.util.Scanner class into the code:

import java.util.Scanner;

Then, we can create the Scanner object in the code and get the integer with the nextInt() function it provides value. The following is a simple example:

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        // 创建Scanner对象
        Scanner scanner = new Scanner(System.in);

        // 提示用户输入整数
        System.out.print("请输入一个整数：");

        // 使用nextInt()函数获取整数值
        int num = scanner.nextInt();

        // 输出获取到的整数值
        System.out.println("您输入的整数是：" + num);

        // 关闭Scanner对象
        scanner.close();
    }
}

In the above code, we first create a Scanner object, which can read user input from the standard input stream. Then, we use the System.out.print() function to output a prompt message to the console, asking the user to enter an integer. Next, use the scanner.nextInt() function to obtain the integer value entered by the user and assign it to the variable num. Finally, we use the System.out.println() function to output the obtained integer value to the console, and close the Scanner object through the scanner.close() function.

The running results of the above code are as follows:

请输入一个整数：10
您输入的整数是：10

As you can see, we successfully obtained the integer value input by the user through the nextInt() function of the Scanner class and output it to on the console.

It should be noted that the nextInt() function can only receive integer values ​​as input, and it will always wait for the user to enter a valid integer value. If the user enters a string or other type of data, the nextInt() function will throw an InputMismatchException. In order to avoid this situation, we can use the hasNextInt() function to make a judgment before calling the nextInt() function to ensure that the user input is a valid integer value. For example:

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        // 创建Scanner对象
        Scanner scanner = new Scanner(System.in);

        // 提示用户输入整数
        System.out.print("请输入一个整数：");

        // 判断用户输入的是否为整数
        if (scanner.hasNextInt()) {
            // 获取整数值
            int num = scanner.nextInt();
            // 输出获取到的整数值
            System.out.println("您输入的整数是：" + num);
        } else {
            // 输出输入错误信息
            System.out.println("输入错误，请输入一个整数！");
        }

        // 关闭Scanner对象
        scanner.close();
    }
}

In the above code, we use the hasNextInt() function to determine whether the user input is an integer. If it is an integer, continue to execute the logic of obtaining the integer value; if it is not an integer, output an error message and require the user to re-enter an integer. This can improve the robustness of the program and avoid program errors caused by user input errors.

To sum up, through the nextInt() function of the Scanner class, we can easily obtain the integer value input by the console and perform subsequent processing in the program. In actual program development, this function is very practical and can meet our input needs. Therefore, mastering how to use the nextInt() function of the Scanner class can improve the efficiency and quality of program development.

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