Example analysis of the usage of Java Scanner class and the problem of line break caused by nextLine of

This paper illustrates the usage of Java Scanner class and the problem of line break caused by nextLine (). Share it for your reference, as follows:

Analysis and understanding: Scanner sc = new Scanner(System.in);

package cn.itcast_01;
/*
 * Scanner: Used to receive data entered by keyboard. 
 *
 *  In front: 
 *     A: Guide pack 
 *     B: Create an object 
 *     C: Invoke method 
 *
 *  Analysis and understanding: Scanner sc = new Scanner(System.in);
 * System Under the class there are 1 Static fields: 
 *     public static final InputStream in;  Standard input stream, corresponding to keyboard entry. 
 *
 *     InputStream is = System.in;
 *
 * class Demo {
 *     public static final int x = 10;
 *     public static final Student s = new Student();
 * }
 * int y = Demo.x;
 * Student s = Demo.s;
 *
 *
 *  Construction method: 
 *     Scanner(InputStream source)
 */
import java.util.Scanner;
public class ScannerDemo {
  public static void main(String[] args) {
    //  Create an object 
    Scanner sc = new Scanner(System.in);
    int x = sc.nextInt();
    System.out.println("x:" + x);
  }
}

Class Scanner hasNextInt() And nextInt() Method

package cn.itcast_02;
import java.util.Scanner;
/*
 *  Basic format: 
 *     public boolean hasNextXxx(): Determine whether it is a certain type of element 
 *     public Xxx nextXxx(): Get the element 
 *
 *  Example: Use int Examples of methods of type 
 *     public boolean hasNextInt()
 *     public int nextInt()
 *
 *  Note: 
 *     InputMismatchException What you entered does not match what you want 
 */
public class ScannerDemo {
  public static void main(String[] args) {
    //  Create an object 
    Scanner sc = new Scanner(System.in);
    //  Get data 
    if (sc.hasNextInt()) {
      int x = sc.nextInt();
      System.out.println("x:" + x);
    } else {
      System.out.println(" The data you entered is incorrect ");
    }
  }
}

In the Scanner class nextLine() The resulting newline character problem

package cn.itcast_03;
import java.util.Scanner;
/*
 *  Two commonly used methods: 
 *     public int nextInt(): Get 1 A int Value of type 
 *     public String nextLine(): Get 1 A String Value of type 
 *
 *  There is a problem: 
 *      Get first 1 Numeric value, when getting the 1 Strings, there will be problems. 
 *      The main reason: It is the problem of the line break symbol. 
 *  How to solve it ?
 *     A: Get first 1 After the number of values is created, the 1 A new keyboard entry object gets a string. 
 *     B: Get all the data according to the string first, and then what you want, you will convert it accordingly. 
 */
public class ScannerDemo {
  public static void main(String[] args) {
    //  Create an object 
    Scanner sc = new Scanner(System.in);
    //  Get two int Value of type 
    // int a = sc.nextInt();
    // int b = sc.nextInt();
    // System.out.println("a:" + a + ",b:" + b);
    // System.out.println("-------------------");
    //  Get two String Value of type 
    // String s1 = sc.nextLine();
    // String s2 = sc.nextLine();
    // System.out.println("s1:" + s1 + ",s2:" + s2);
    // System.out.println("-------------------");
    //  Get first 1 String, when getting the 1 A int Value 
    // String s1 = sc.nextLine();
    // int b = sc.nextInt();
    // System.out.println("s1:" + s1 + ",b:" + b);
    // System.out.println("-------------------");
    //  Get first 1 A int Value, when getting the 1 String, there will be a problem here 
    // int a = sc.nextInt();
    // String s2 = sc.nextLine();
    // System.out.println("a:" + a + ",s2:" + s2);
    // System.out.println("-------------------");
    int a = sc.nextInt();
    Scanner sc2 = new Scanner(System.in);
    String s = sc2.nextLine();
    System.out.println("a:" + a + ",s:" + s);
  }
}

For more readers interested in java related content, please check the topics of this site: "Summary of Java File and Directory Operation Skills", "Java Data Structure and Algorithm Tutorial", "Summary of Java Operation DOM Node Skills" and "Summary of Java Cache Operation Skills"

I hope this article is helpful to everyone's java programming.