Java Scanner

java.util.Scanner Java5 Scanner

Scanner

Scanner s = new Scanner(System.in);

Scanner next() nextLine() hasNext hasNextLine

next

ScannerDemo.java

import java.util.Scanner; public class ScannerDemo { public static void main(String[] args) { Scanner scan = new Scanner(System.in); // // next System.out.println("next"); // if (scan.hasNext()) { String str1 = scan.next(); System.out.println("" + str1); } scan.close(); } }

$ javac ScannerDemo.java
$ java ScannerDemo
next
runoob com
runoob

com nextLine

nextLine

ScannerDemo.java

import java.util.Scanner; public class ScannerDemo { public static void main(String[] args) { Scanner scan = new Scanner(System.in); // // nextLine System.out.println("nextLine"); // if (scan.hasNextLine()) { String str2 = scan.nextLine(); System.out.println("" + str2); } scan.close(); } }

$ javac ScannerDemo.java
$ java ScannerDemo
nextLine
runoob com
runoob com

com

next() nextLine()

next():

  • 1
  • 2next()
  • 3
  • next()

nextLine()

  • 1Enter, nextLine()
  • 2

int float Scanner hasNextXxx() nextXxx()

ScannerDemo.java

import java.util.Scanner; public class ScannerDemo { public static void main(String[] args) { Scanner scan = new Scanner(System.in); // int i = 0; float f = 0.0f; System.out.print(""); if (scan.hasNextInt()) { // i = scan.nextInt(); // System.out.println("" + i); } else { // System.out.println(""); } System.out.print(""); if (scan.hasNextFloat()) { // f = scan.nextFloat(); // System.out.println("" + f); } else { // System.out.println(""); } scan.close(); } }

$ javac ScannerDemo.java
$ java ScannerDemo
12
12
1.2
1.2

ScannerDemo.java

import java.util.Scanner; class RunoobTest { public static void main(String[] args) { System.out.println(""); Scanner scan = new Scanner(System.in); double sum = 0; int m = 0; while (scan.hasNextDouble()) { double x = scan.nextDouble(); m = m + 1; sum = sum + x; } System.out.println(m + "" + sum); System.out.println(m + "" + (sum / m)); scan.close(); } }

$ javac ScannerDemo.java
$ java ScannerDemo

12
23
15
21.4
end
471.4
417.85

Scanner(File source) Scanner
Scanner(InputStream source) Scanner
Scanner(String source) Scanner
boolean hasNext()
String next()
boolean hasNextLine()
String nextLine()
boolean hasNextInt()
boolean hasNextDouble()
boolean hasNextBoolean()
int nextInt()
double nextDouble()
boolean nextBoolean()
long nextLong()
float nextFloat()
short nextShort()
byte nextByte()
Scanner useDelimiter(String pattern)
Scanner useDelimiter(Pattern pattern)
String delimiter()
void close()
Scanner skip(Pattern pattern)
Scanner skip(String pattern)
String findInLine(Pattern pattern)
String findInLine(String pattern)
Scanner reset()
Locale locale()
Scanner useLocale(Locale locale)

API https://www.runoob.com/manual/jdk11api/java.base/java/util/Scanner.html