import java.util.Scanner; 

class Daytwo{
    public static void main(String[] args){
        System.out.println("HelloWorld");

        Scanner reader = new Scanner(System.in);
        System.out.println("Enter the number ");

        int n = reader.nextInt();
        System.out.println("You entered " + n);

    }
}

你可以做一个简单的程序，要求用户的名字和打印任何回复使用输入。

或者让用户输入两个数字，你可以加、乘、减或除这些数字，并打印出用户输入的答案，就像计算器的行为一样。

你需要Scanner类。你必须导入java。util。scanner;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和double类型以同样的方式变化。不要忘记代码顶部的import语句。

请参见博客文章“扫描器类和获取用户输入”。

您可以使用Scanner获取用户输入。您可以使用正确的方法对不同的数据类型使用正确的输入验证，例如对String使用next()，对Integer使用nextInt()。

import java.util.Scanner;

Scanner scanner = new Scanner(System.in);

//reads the input until it reaches the space
System.out.println("Enter a string: ");
String str = scanner.next();
System.out.println("str = " + str);

//reads until the end of line
String aLine = scanner.nextLine();

//reads the integer
System.out.println("Enter an integer num: ");
int num = scanner.nextInt();
System.out.println("num = " + num);

//reads the double value
System.out.println("Enter a double: ");
double aDouble = scanner.nextDouble();
System.out.println("double = " + aDouble);


//reads the float value, long value, boolean value, byte and short
double aFloat = scanner.nextFloat();
long aLong = scanner.nextLong();
boolean aBoolean = scanner.nextBoolean();
byte aByte = scanner.nextByte();
short aShort = scanner.nextShort();

scanner.close();

最简单的方法之一是使用Scanner对象，如下所示:

import java.util.Scanner;

Scanner reader = new Scanner(System.in);  // Reading from System.in
System.out.println("Enter a number: ");
int n = reader.nextInt(); // Scans the next token of the input as an int.
//once finished
reader.close();

下面是获取键盘输入的方法:

Scanner scanner = new Scanner (System.in);
System.out.print("Enter your name");  
String name = scanner.next(); // Get what the user types.

在这里，程序要求用户输入一个数字。在此之后，程序打印数字的数字和数字的和。

import java.util.Scanner;

public class PrintNumber {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int num = 0;
        int sum = 0;

        System.out.println(
            "Please enter a number to show its digits");
        num = scan.nextInt();

        System.out.println(
            "Here are the digits and the sum of the digits");
        while (num > 0) {
            System.out.println("==>" + num % 10);
            sum += num % 10;
            num = num / 10;   
        }
        System.out.println("Sum is " + sum);            
    }
}