Scanner Class Diagram

Ancestor class specifications:

java.lang.Object

Scanner Class Specification

Invariant

A Scanner object...

- is designed to extract tokens from a string

- 0 <= pos <= scanText.length

Constructor Methods

public Scanner( Strings )

post: scanText == s

public Scanner( InputStream is )

post: scanText == text from stream is

Query Methods

public String next( )

pre: hasNext()

post: Scanning began with scanText[pos@pre]. All leading delimiters (white space) are skipped and scanning ends with the delimiter (or end of string) following non-delimiter text

and result == the non-delimiter text

and pos is advanced to the index of the delimiter following the non-delimiter

text

public boolean nextBoolean( )

pre: hasNextBoolean()

post: Scanning began with scanText[pos@pre]. All leading delimiters (white space) are skipped and scanning ends with the delimiter (or end of string) following the boolean literal (true or false)

and result == the scanned literal

and pos is advanced to the index of the delimiter following the literal

public byte nextByte( )

pre: hasNextByte()

post: Scanning began with scanText[pos@pre]. All leading delimiters (white space) are skipped and scanning ends with the delimiter (or end of string) following the byte literal (integer)

and result == the scanned literal

and pos is advanced to the index of the delimiter following the literal

public double nextDouble( )

pre: hasNextDouble()

post: Scanning began with scanText[pos@pre]. All leading delimiters (white space) are skipped and scanning ends with the delimiter (or end of string) following the double literal (real number)

and result == the scanned literal

and pos is advanced to the index of the delimiter following the literal

public float nextFloat( )

pre: hasNextFloat()

post: Scanning began with scanText[pos@pre]. All leading delimiters (white space) are skipped and scanning ends with the delimiter (or end of string) following the float literal (real number)

and result == the scanned literal

and pos is advanced to the index of the delimiter following the literal

public int nextInt( )

pre: hasNextInt()

post: Scanning began with scanText[pos@pre]. All leading delimiters (white space) are skipped and scanning ends with the delimiter (or end of string) following the int literal (integer)

and result == the scanned literal

and pos is advanced to the index of the delimiter following the literal

public String nextLine( )

pre: hasNextDouble()

post: Scanning began with scanText[pos@pre]. All leading delimiters (white space) are skipped and scanning ends with the first encountered “\n” (or end of string)

and result == the scanned line

and pos is advanced to the index of the delimiter following the line

public long nextLong )

pre: hasNextLong()

post: Scanning began with scanText[pos@pre]. All leading delimiters (white space) are skipped and scanning ends with the delimiter (or end of string) following the long literal (integer)

and result == the scanned literal

and pos is advanced to the index of the delimiter following the literal

public short nextShort( )

pre: hasNextShort()

post: Scanning began with scanText[pos@pre]. All leading delimiters (white space) are skipped and scanning ends with the delimiter (or end of string) following the short literal (integer)

and result == the scanned literal

and pos is advanced to the index of the delimiter following the literal

Predicate Methods

public boolean hasNextBoolean( )

post: result == the text from scanText[pos] is a proper boolean literal (true or false), optionally preceded by delimiter (white space) characters and terminated with a delimiter or the end of scanText.

public boolean hasNextByte( )

post: result == the text from scanText[pos] is a proper byte literal (integer), optionally preceded by delimiter (white space) characters and terminated with a delimiter or the end of scanText.

public boolean hasNextDouble( )

post: result == the text from scanText[pos] is a proper double literal (real number), optionally preceded by delimiter (white space) characters and terminated with a delimiter or the end of scanText.

public boolean hasNextFloat( )

post: result == the text from scanText[pos] is a proper float literal (real number), optionally preceded by delimiter (white space) characters and terminated with a delimiter or the end of scanText.

public boolean hasNextInt( )

post: result == the text from scanText[pos] is a proper int literal (integer), optionally preceded by delimiter (white space) characters and terminated with a delimiter or the end of scanText.

public boolean hasNextLong( )

post: result == the text from scanText[pos] is a proper long literal (integer), optionally preceded by delimiter (white space) characters and terminated with a delimiter or the end of scanText.

public boolean hasNextShort( )

post: result == the text from scanText[pos] is a proper short literal (integer), optionally preceded by delimiter (white space) characters and terminated with a delimiter or the end of scanText.