使用标准值控制循环 输入和输出重定向

使用while循环实现

import java.util.*;
class Main {
  public static void main(String[] args){
    //Create a Scanner
    Scanner input = new Scanner(System.in);
    
    //Read an initial data
    System.out.print("Enter an int value(the pogram exits if the input is 0): ");
    int data = input.nextInt();

    //Keep reading data until the input is 0
    int sum = 0;
    while(data != 0){
      sum += data;

      //Read the next data
      System.out.print("Enter an int value(the pogram exits if the input is 0): ");
      data = input.nextInt();
    }
    System.out.println("The sum is " + sum);
  }
}

使用do while 循环实现

import java.util.*;
class Main {
  public static void main(String[] args){
    //Create a Scanner
    Scanner input = new Scanner(System.in);
    int sum = 0;
    int data;
    do{
      //Read an initial data
      System.out.print("Enter an int value(the pogram exits if the input is 0): ");
      data = input.nextInt();
      sum += data;
    }while(data != 0);
    
    System.out.println("The sum is " + sum);
  }
}

输入和输出重定向

dos 命令行执行
java ClassName < input.txt 程序从input.txt中读取输入
java ClassName > output.txt 程序将输出发送给文件 output.txt

== java ClassName < input.txt >output.txt == 程序从input.txt中读取输入并将输出发送给文件output.txt