How to get input data in java

The mechanisms for obtaining input data in Java include: Console input: Use the Scanner class to read integers, strings, and floating point numbers from the console. Command line parameters: Get input data from command line parameters. File input: Use the File class to read data from a file.

Mechanisms for getting input data in Java

Java provides multiple mechanisms to get input data from the user or other sources Input data.

Console input

The most common method is to use java.util.Scanner Class:

import java.util.Scanner;

public class InputExample {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        // 获取整数
        System.out.println("请输入一个整数：");
        int number = scanner.nextInt();

        // 获取字符串
        System.out.println("请输入一个字符串：");
        String text = scanner.nextLine();

        // 获取浮点数
        System.out.println("请输入一个浮点数：");
        double decimal = scanner.nextDouble();

        scanner.close();
    }
}

Command line parameters

You can also get input data from command line parameters:

public class CommandLineArgsExample {

    public static void main(String[] args) {
        if (args.length > 0) {

            // 获取第一个命令行参数
            String firstArg = args[0];

            // 获取所有命令行参数
            for (String arg : args) {
                System.out.println(arg);
            }
        } else {
            System.out.println("未提供命令行参数。");
        }
    }
}

File input

You can usejava .io.File class reads data from a file:

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

public class FileInputExample {

    public static void main(String[] args) {
        try {
            File file = new File("input.txt");
            Scanner scanner = new Scanner(file);

            while (scanner.hasNextLine()) {
                String line = scanner.nextLine();
                System.out.println(line);
            }

            scanner.close();
        } catch (FileNotFoundException e) {
            System.out.println("文件未找到。");
        }
    }
}

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