你可以流动这段代码:

Scanner obj= new Scanner(System.in);
String s = obj.nextLine();

读取输入: 扫描仪扫描仪=新的扫描仪(System.in); 字符串输入= scanner.nextLine(); 当你调用一个带有参数/形参的方法时读取输入: 如果(arg游戏。长度!= 2){ System.err。println(" utilzare: java Grep < filier > <cuvant>"); system . exit (1); ｝ 尝试{ grep (args [0], arg游戏[1]); } catch (IOException e) { System.out.println (e.getMessage ()); ｝

您可以编写一个简单的程序来询问用户的姓名，并打印任何回复使用的输入。

或者要求用户输入两个数字，您可以对这些数字进行加、乘、减或除，并像计算器一样打印用户输入的答案。

这里你需要Scanner类。你必须导入java.util.Scanner;，并且在你需要使用的代码中:

Scanner input = new Scanner(System.in);

Input是一个变量名。

Scanner input = new Scanner(System.in);

System.out.println("Please enter your name: ");
s = input.next(); // Getting a String value

System.out.println("Please enter your age: ");
i = input.nextInt(); // Getting an integer

System.out.println("Please enter your salary: ");
d = input.nextDouble(); // Getting a double

看看这有什么不同:input.next();， i = input.nextInt();， d = input.nextDouble();

根据String类型，int类型和double类型的变化方式与其他类型相同。不要忘记代码顶部的import语句。

举个简单的例子:

import java.util.Scanner;

public class Example
{
    public static void main(String[] args)
    {
        int number1, number2, sum;

        Scanner input = new Scanner(System.in);

        System.out.println("Enter First multiple");
        number1 = input.nextInt();

        System.out.println("Enter second multiple");
        number2 = input.nextInt();

        sum = number1 * number2;

        System.out.printf("The product of both number is %d", sum);
    }
}

当用户输入他/她的用户名时，也检查是否有有效的输入。

java.util.Scanner input = new java.util.Scanner(System.in);
String userName;
final int validLength = 6; // This is the valid length of an user name

System.out.print("Please enter the username: ");
userName = input.nextLine();

while(userName.length() < validLength) {

    // If the user enters less than validLength characters
    // ask for entering again
    System.out.println(
        "\nUsername needs to be " + validLength + " character long");

    System.out.print("\nPlease enter the username again: ");
    userName = input.nextLine();
}

System.out.println("Username is: " + userName);

下面是执行所需操作的完整类:

import java.util.Scanner;

public class App {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        final int valid = 6;

        Scanner one = new Scanner(System.in);
        System.out.println("Enter your username: ");
        String s = one.nextLine();

        if (s.length() < valid) {
            System.out.println("Enter a valid username");
            System.out.println(
                "User name must contain " + valid + " characters");
            System.out.println("Enter again: ");
            s = one.nextLine();
        }

        System.out.println("Username accepted: " + s);

        Scanner two = new Scanner(System.in);
        System.out.println("Enter your age: ");
        int a = two.nextInt();
        System.out.println("Age accepted: " + a);

        Scanner three = new Scanner(System.in);
        System.out.println("Enter your sex: ");
        String sex = three.nextLine();
        System.out.println("Sex accepted: " + sex);
    }
}