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);            
    }
}

要读取一行或字符串，你可以使用BufferedReader对象和InputStreamReader对象结合使用，如下所示:

BufferedReader bufferReader = new BufferedReader(new InputStreamReader(System.in));
String inputLine = bufferReader.readLine();

这是一个使用System.in.read()函数的简单代码。这段代码只是写出输入的内容。如果您只想获取一次输入，可以去掉while循环，如果您愿意，可以将答案存储在字符数组中。

package main;

import java.io.IOException;

public class Root 
{   
    public static void main(String[] args)
    {
        new Root();
    }

    public Root()
    {
        while(true)
        {
            try
            {
                for(int y = 0; y < System.in.available(); ++y)
                { 
                    System.out.print((char)System.in.read()); 
                }
            }
            catch(IOException ex)
            {
                ex.printStackTrace(System.out);
                break;
            }
        }
    }   
}    

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.

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();

import java.util.Scanner;

public class Myapplication{
     public static void main(String[] args){
         Scanner in = new Scanner(System.in);
         int a;
         System.out.println("enter:");
         a = in.nextInt();
         System.out.println("Number is= " + a);
     }
}