[Java] The difference and usage of next() and nextLine() in Scanner

        The Scanner class is used for keyboard input and needs to import the java.util.Scanner package when using it. Here are several commonly used keyboard input methods:

method	description
nextBoolean()	Scan the next tag entered as a Boolean value and return that value
nextByte()	Scan the next tag entered as byte
nextDouble()	Scan the next token entered as double
nextFloat	Scan the next tag entered as a float
nextInt ()	Scan the next token entered as int
nextLine()	Advance this scanner to the current line and return the skipped input
nextLong()	Scan the input next token as long
nextShort()	Scan the next token entered as short
next()	Find and return the next full token for this scanner

Among them, the return values ​​of next() and nextLine() are both string types. There are some disadvantages when using both:

nextLine()的缺点：
    1）nextLine()方法前面不能出现其他的键盘输入方法
    2）nextLine()方法前面可以有一个nextLine()方法
next()的缺点：
    不能接受空格和回车

nextLine():

package com.itheima;

import java.util.Scanner;

public class Test {
    // nextLine()的缺点：
    // nextLine()方法前面不能出现其他的键盘输入方法
    public static void main(String[] args) {
        Scanner scanner=new Scanner(System.in);
        System.out.println("请输入一个整数：");
        int num=scanner.nextInt();
        System.out.println(num);
        System.out.println("请输入一个字符串：");
        String s=scanner.nextLine();
        System.out.println(s);
    }
}

        But if nextLine() is still a nextLint() method, the output is normal

package com.itheima;

import java.util.Scanner;

public class Test {
    // nextLine()的缺点：
    // nextLine()方法前面不能出现其他的键盘输入方法
    // nextLine()前面可以在有一个nextLine()
    public static void main(String[] args) {
        Scanner scanner=new Scanner(System.in);
        System.out.println("请输入一个字符串：");
        String num=scanner.nextLine();
        System.out.println(num);
        System.out.println("请输入一个字符串：");
        String s=scanner.nextLine();
        System.out.println(s);
    }
}

next（）：

package com.itheima;

import java.util.Scanner;

public class Test {
    // next()的缺点：
    // 不能接受空格和回车
    public static void main(String[] args) {
        Scanner scanner=new Scanner(System.in);
        System.out.println("请输入一个字符串：");
        String num=scanner.next();
        System.out.println(num);
    }
}