Scanner

 1 package cn.itcast_01;  2 /* 
 3 Scanner: 用于接收键盘录入数据.  4 录入数据格式:  5  导包,建立对象,调用方法  6     
 7 System类下有一个静态字段:  8  public static final InputStream in; 标准输入流, 对应键盘输入  9  InputStream is = System.in; 10     
11 class Demo 12 { 13  public static final int x = 10; 14  public static final Student s = new Student(); 15     
16 } 17 int y = Demo.x; 18 Student s = Demo.s; 19 
20 构造方法: 21  Scanner(InputStream source) 22 
23  */
24  
25 import java.util.Scanner; 26 public class ScannerDemo 27 { 28     public static void main(String[] args){ 29         //建立对象 
30         Scanner s = new Scanner(System.in); 31         int x = s.nextInt(); 32         System.out.println("x = " + x); 33  } 34 }

/* 基本格式: public boolean hasNextXxx(): 判断是否为某事类型的元素 public Xxx nextXxx(): 获取该元素 举例: int 类型 public boolean hasNextInt() public int nextInt() 注意: InputMismatchException: 输入不匹配异常 */

package cn.itcast_02; import java.util.Scanner; public class ScannerDemo2 { public static void main(String[] args){ //建立对象
        Scanner sc = new Scanner(System.in); //输入字符串致使InputMisMatchException; // int x = sc.nextInt(); // System.out.println("x = " + x);
        
        if(sc.hasNextInt()){ int x = sc.nextInt(); System.out.println("x = " + x); }else{ System.out.println("你输入错误"); } } }