Java.util class Scanner text scanner

Text-based scanner 10. Scanner java.util

• A regular expression can be used to parse simple text strings and basic types of scanners.

Construction method of receiving System.in,  and File InputStream

• public Scanner (File source): Constructs a new Scanner, which produces values scanned from the specified file.
• public Scanner (InputStream source): Constructs a new Scanner, produces values specified from the input stream is scanned.
• public Scanner (String source): Constructs a new Scanner, produces values scanned from the specified string.

Common method , , , hasNext() hasNextXx() next() nextXx()

• public boolean hasNext (): If the input of this scanner has another flag, it returns true.
• public boolean hasNextLine (): If there is input of this scanner is another line, it returns true.
• public boolean hasNextInt (): a default radix int Returns true if the method, a tag scanner's input this information by using the nextInt () can be interpreted. The scanner does not perform any input.
• public boolean hasNextInt (int radix): if () method, this scanner's input information by a tag can be interpreted as nextInt using an int value specified radix, it returns true. The scanner does not perform any input.
  • hasNextBigDecimal(),hasNextBigInteger(), hasNextBoolean(), hasNextByte(), hasNextDouble(), hasNextFloat(), hasNextLong(),hasNextShort()
• public String next (): Finds and returns the next complete token from this scanner.
• public String nextLine (): This scanner past the current line, and returns the input skipped.
• public int nextInt (): the input of the next scanning information marker as an int.
• public int nextInt (int radix): the input of the next scanning information into a tag int, radix used to interpret the token int cardinality.
  • nextBigDecimal(),nextBigInteger(),,,,,, NextBoolean() NextByte() NextDouble() NextFloat() NextLong() NextShort()
• public void close (): Closes this scanner.

Knowledge extension

1, the receiving console input

    Scanner sc = new Scanner(System.in);
    while (sc.hasNext()) {
        //String name = sc.nextLine();
        int age = sc.nextInt();
        //float salary = sc.nextFloat(); 
        if (age > 100) {
            age = 100;
        }

2, next () and nextLine () difference

next():
    1、一定要读取到有效字符后才可以结束输入。
    2、对输入有效字符之前遇到的空白，next() 方法会自动将其去掉。
    3、只有输入有效字符后才将其后面输入的空白作为分隔符或者结束符。 
    next() 不能得到带有空格的字符串。
nextLine()： 
    1、以Enter为结束符,也就是说 nextLine()方法返回的是输入回车之前的所有字符。 
    2、可以获得空白。

<https://blog.csdn.net/ZytheMoon/article/details/79293516>