输入输出

https://www.nowcoder.com/test/27976983/summary#question

1、多组输入求和

import java.util.*;
public class Main{
    public static void main(String[] args){
        Scanner s = new Scanner(System.in);
        while(s.hasNext()){//s.hasNext()会指向下一行
            int a = s.nextInt();            
            int b = s.nextInt();
            System.out.println(a+b);
        }
    }
}

2、如果给定了组数

import java.util.*;
public class Main{
    public static void main(String[] args){
        Scanner s = new Scanner(System.in);
        int cnt = s.nextInt();
        s.nextLine();//使用完nextInt必须要有这一步
        while(cnt>0){
            int a = s.nextInt();            
            int b = s.nextInt();
            System.out.println(a+b);
            cnt--;
        }
    }
}

3、如果要判断输入

import java.util.*;
public class Main{
    public static void main(String[] args){
        Scanner s = new Scanner(System.in);
        while(s.hasNext()){
            int a = s.nextInt();            
            int b = s.nextInt();
            if(a==0&&b==0){
                break;
            }
            System.out.println(a+b);
        }
    }
}

4、第一个字表示后面的个数

import java.util.*;
public class Main{
    public static void main(String[] args){
        Scanner s = new Scanner(System.in);
        while(s.hasNext()){
            int cnt = s.nextInt();
            if(cnt==0){
                break;
            }
            int sum = 0;
            while(cnt>0){
                sum = sum+s.nextInt();
                cnt--;
            }
            System.out.println(sum);
        }
    }
}

5、hasNext()和nextLine()配合使用：

输入未知次数的字符串

public static void main(String args[]){
        Scanner s = new Scanner(System.in);
        while(s.hasNext()){
            separate(s.nextLine());
        }  
}